TROUBLESHOOTING LP-GAS SYSTEMS
Contents
1. June 1998 Number 16 INSIDE LETTERS COACH TALK Fuet Hoses 30R7 30R9 ALCOA PART Numsers WHEELS CentER CAPS Luc Nuts Nut Covers AIR BAG SUBSTITUTE e Hot WATER Deposits SHOWER DRAIN SHINY TIRES e Low VOLTAGE TRANSMISSION VENT e LEAKING Winpows SKIRT BRACKET ONAN CONTROL COMBINATION VALVE COACH TALK INDEX CLASSIFIED ADVERTISEMENTS TROUBLESHOOTING LP GAS SYSTEMS Few GMC Motorhome owners realize that the LP gas distribution system requires any more atten tion than turning a tank valve on before lighting a burner and filling the tank once in a while Proper operation of appliances such as the refrigerator and furnace depends heavily on proper function of the system but it rarely gets any attention unless a problem with one of the appliances is obvious Over a year s time a well designed distribution system can be called upon to receive LP gas vapor at pressures ranging from well over 200 psi to less than 10 psi Nevertheless the sy LP gas vapor steadily to one or more appliances operating simultaneously at a pressure of 11 inches WC water column with a variation of no more than plus or minus one inch WC That s a demand ing performance specification for any system be cause 11 inches WC is only 0 4 psi and it should be checked at least once a year particularly in em will deliver the spring if the motorhome has been in storage all2. 1976 Eleganza II 26 foot Side Bath 108 000 Original Miles New Engine At 85 000 New Tires Carpet Shades Batter ies Radiator Steering Gear Toilet Air Bags Bilsteins At 100 000 Two Roof AC Pod Zip Dee Awning 25 000 OBO Don Kring New Haven IN 219 493 6078 1976 Birchaven 23 foot Side Bath 111 000 Original Miles Rebuilt Engine And Transmission Pull Down Bunk In Rear For Two Small Kids Well Maintained Runs Great 15 000 Ronald Porter Redford Township MI 313 534 8147 1976 Royale 26 foot Dry Bath 455 cid Engine Center Kitchen New Frame Brake Drums Final Drive Roof Pod Rebuilt Transmission All Equipment In Working Condition 20 000 Ken Wojahn East Tawas MI 517 362 3859 1975 Eleganza II 26 foot Side Bath 75 000 Original Miles Headers Michelins Alcoa Wheels Transmission Cooler 3 42 Final Drive Bilsteins Suburban Furnace 3 Way Refrigerator CD Radio Stored Inside All Service Manuals 19 000 John Northrup Howell MI 517 548 4950 1975 Palm Beach 26 foot Side Bath Uncommon Find Beautiful Original Condition Two Roof AC Microwave CB Radio Stored Indoors 18 500 J R Linkous P Box 246 White Sulphur Springs WV 24986 304 536 1226 1975 Avion 23 foot Dry Side Bath 60 000 Original Miles Loaded Always Garaged 25 000 OBO Clarence Martin Cleveland Heights O 16 291 4921 1973 26 foot Side Bath Restored With Low Mileage On Rebuilt Engine Every
3. Brakes Air Bags Headers Shocks Belts Hoses New Refrigerator Microwave Converter Commode Must Sell 18 500 Ethelyn 1978 Eleganza II 26 foot Side Bath Rebuilt 403 cid Engine And Onan New 3 Way Refrigerator Tires Converter Belts Chairs Hoses Headliner Front End Steering Wheel Bearings Brakes Battery Isolator Holding Tank 25 000 John Thrasher Phoenix AZ 602 867 2827 1978 Royale 26 foot Rear Bath Twin Beds 11 000 Miles On Rebuilt 455 cid Engine And Transmission Seven New Alcoa Wheels New Bilsteins And Awnings Hitch 25 000 Matt Matthews San Clemente CA 949 492 5957 1977 26 foot Side Bath Restored With Low Mileage On Rebuilt Engine Everything Works Excellent Condition 28 000 Located In Jackson MS 800 844 2000 Extension 2458 1977 Palm Beach 26 foot Side Bath Two Roof AC Ladder Rack And Storage Pod Complete Front Wheel Drive Engine Transmission Air Bags Garaged Extra Parts 25 000 OBO Leon Ficchi Flagtown NJ 908 369 3761 1977 Kingsley 26 foot Side Bath Upgraded Refrigeration And Heating Unit Overhauled 455 cid Engine And Transmission Needs Interior Work And Paint Sleeps Six 15 000 Firm Al Gotelli Stockton CA 209 931 4392 1977 Coca Cola 26 foot Side Bath Original Interior Microwave Two Roof AC New Tires Air Bags Jardine Exhaust New 3 Way Refrigerator Great Condition 22 000 OBO A M VanderKolk Grand Rapid
4. Tires And Wheel Covers Included Make Offer Two Armstrong 16 5 X6 75 Radial Wheels 40 Winslow River Forest IL 708 h Bruce 771 6471 1977 Palm Beach Parts Captain s Chairs Couch Rear Seats Cabi netry Refrigerator And Other Parts Tom Bradley Chandler AZ 602 814 1631 Complete A amp E 18 Foot Awning With Hardware 500 One Pair 1 5 Inch Rear Control Arms With Axle Spindles 350 Two Drive Axles 150 John Stewart Salt Lake City UT 801 467 0293 Advertising Subscribers are entitled to one noncom mercial classified advertisement per year at no charge Additional noncommercial advertisements in the same year are 1 each Commercial Advertising Rates are available on request Direct advertising to Mrs Lorraine Graham Cinnabar Engi neering Inc 116 Orval Street Sandusky Michigan 4847 L 810 648 2445 FAX 810 648 9858 The closing date for the September 1998 issue is August 15 1998 We Build Custom and Standard Engines for GMC Motorhomes We Can Bring Them To You
5. and turn on at least one other burner or the oven When you open the valve leading to the manometer the water in one of the legs will drop and the water in the other leg will rise The system pressure is the difference between the heights of the water columns in the legs and should ideally be 11 0 inches WC in the summertime In the wintertime 10 5 inches WC will be around 11 0 inches next summer because of normal temperature effects on the gas in exposed plumbing If you do not get a reading of 10 5 to 11 0 inches your regulator may need ad justment If you don t know what or where the regulator is located you should seek the assistance of someone who does Oth erwise raise or lower the system pressure by increasing or decre asing the regulator s spring pressure turning the adjustment in the regulators top clockwise or counter clockwise until you get a reading of 10 5 to 11 0 inches Once you have reached a normal set A simple U tube manometer can be built for about 5 in le column WC in this pressure check was 10 5 inche s than an hour The water ting of 10 5 to 11 0 inches watch the ma nometer for a while The water columns should not float or change rapidly If they do the regulator may not be working properly or it may be freezing particularly if it is a typical low capacity unit Or you may have air in the tank which should have been vapor pressure purged four to five times w
6. gas tank valve Then go back inside the motorhome and slowly open one of the stove burners just enough to lower the system pressure to 10 0 inches WC Stand back for 10 minutes and then read the manometer If the system pressure is less than 10 0 inches after 10 minutes get out the soap solution because you have a leak If the system pressure is more than 10 0 inches after 10 minutes the tank valve leaks and it should be repaired or replaced by an LP gas serviceman because replacement requires emptying the tank and vapor pressure purging before refilling If the system pressure is still 10 0 inches after 10 minutes the sys tem can be assumed to be leal Unfortunately most GMC Motorhomes will not pass all of these tests and many of them didn t pass when they were new The problem turned out to be an inade quate regulator The original equipment regulator worked fine in the summer time and in the fall but it would freeze in northern Michigan in the wintertime Fortunately the distribution system pipe sizes were adequate because you are pretty much stuck with them once the motorhome is built However if you are remodeling your motorhome consider able attention should be paid to pipe size If they are inadequate they can cause intolerable system pressure drops as appli ances cycle on and off It is the same phe nomenon most of us have experienced in a shower when someone flushes a toilet nearby Recommended mani
7. has caused a number of GMC Motorhome fires Some of these fires have totally destroyed the motorhomes For some time we have been extend ing the transmission vent to the side of the motorhome Once this is done any expelled fluid will drain onto the ground and not onto a hot exhaust pipe Recently Bob DeSaussure of San Rafael California sent me a drawing of a do it yourself vent o from the rubber si A transmission vent extension will direct any fluid expulsion away from hot parts extension that anyone can install after prying off the vent cap The parts consist of a molded rubber elbow with a inch inside diameter a short length of inch copper tubing 38 inches of X i inch fuel hose one hose clamp and a vent cap The molded rubber elbow can be cut out of a GM PCV hose GM part number 25508425 yields three elbows Give the extra elbows to your friends The vent cap is GM part number 8640496 and it is stocked by most GM car and truck dealers Once the vent cap is pried off install one end of the elbow on the vent nipple and secure it with the hose clamp Mea sure the length of inch fuel hose from the end of the elbow to the side of the motorhome and cut the hose Cut it a little short to allow for the length of the new vent cap The hose easily runs in the strapped U channel under the floor above the vent The last strap on the U channel creates a restin
8. lug nuts Those with an investment stock and sell complete Alcoa packages which in clude the wheels lug nuts decorative hard ware and longer GM stud bolts Finally some sell attractive packages that include mounted and balanced LT225 75R16 LRE 10 ply rated all steel tires The Alcoa aluminum wheel for the GMC Motorhome is Alcoa part number 160231 and it comes with a TR 543 The Alcoa 160231 Wheel 003611 Center Cap and 000190 Hug A Lug Nut Covers valve The Alcoa part number for the lug nuts is 139987 The GM part number for the longer stud bolts is 704922 These stud bolts are for aluminum or steel wheels with or without wheel covers New front and rear hubs come with the longer stud bolts already installed Now let s stop for a moment because the Alcoa lug nuts are as important as the longer GM stud bolts that meet the Alcoa minimum stud standout requirement of 1 5 inches Lug nuts are one of the ways that brokers quote lower prices They sell an aftermarket lug nut that is much cheap er than the Alcoa lug nut and their pack age price can be cheaper Unfortunately the quality isn t there according to Alcoa and other experts in the wheel industry The two piece flange nut used on Alcoa wheels was first used on Ford wheels years ago It works fine when it is properly made and not over torque are few aftermarket nuts that have the substance to withstand excessive torque Unfortunately t
9. same When the pressure to be measured is applied to one leg the water will drop and the water in the opposing leg will rise The water column WC is the difference between the heights of the water columns in the legs of the U We prefer and recommend a U tube manome ter for measuring and monitoring LP g tion system pressures because we have found very as distribu few accurate gauges Most gauges are Bourdon tube gauges that are very fragile because the tube must be very sensitive to measure pressures less than one psi The gauges are more convenient for the average serviceman but they usually just get thrown into his toolbox along with the rest of his tools Unfortunately the first throw into the tool box often ruins the gauge s calibration Still most servicemen rely few check its calibration regularly To top it all off these low pressure gauges are expensive but you clusively on their gauge and can build an always accurate U tube water ma nometer in about an hour with about 5 worth of local hardware store materials Such a homemade manometer consists of a piec of 16 inch pine lumber about two feet long six feet of X inch clear plastic tubing and four electri cal staples Its feet can be just about anything that will hold it vertical or it can be hung on the wall with a nail To function properly it simply needs to be vertical so the heights of the water columns in the legs of
10. the back of Maintenance Manual X 7525 Just about all vehicle lighting passes through the headlight switch but there are connectors before it and after it Then The main fusible link arrow looks heavier than its 16 gauge internal wire GMC Motorhome News June 1998 there are the connectors in all of the branch circuits The turn signals and hazard signals come off the battery bus through a 20 amp fuse behind the glove compartment If you get the same voltage from a taillight signal and a turn signal you can probably eliminate everything before the switch and the fuse block except the fusible link The fusible link is often the culprit It heavily insulated 16 gauge wire of a spe cific length that is like a main circuit breaker in your home The wiring diagram shows wire color wire size connectors and the individual lights I suspect you will find a loose or corroded connector or a weakened fusible link that is causing your problem I encour age you to find it because a 3 volt drop indicates a resistance that is putting out a lot of heat if it is all in one pla ce Transmission Vent When I start my motorhome after it hu for a few days a s fluid is expelled from the vent After the initial expulsion everything is fine The transmission nall amount of transmissi is not oveyfilled In fact the fluid level measures almost a pint low when it is hot The pelled fluid accumulate
11. with the body of the motorhome luck Do you know where I can find a GMC Moi home News June 1998 wiring diagram for the Onan generator Can problem is almost always with the inside you suggest a fix control or the wiring in between the Dave Griffith Onan and the control To make Onan Cincinnati Ohio installation easier on the production line General Motors put a connector in the ou re on the right track Dave When wiring that goes to the inside control you can start and stop an Onan The connector is located at the rear of from the outside but not the inside the the Onan compartment After pulling the BILSTEIN RV Shock Treatment Now there are shock absorbers strong enough to deliver a lifetime of peak efficiency for today s motorhomes Lappe Sigan internally Revolutionary mono tube design 360 psi internal pressure With Bilstein you get The world leader in gas pressure shock technology Better heat dissipation 98 efficiency over 100 000 miles Largest piston diameter 1 8 Unique deflective disc valving system for consistent control Highest gas pressure 360psi eliminates foaming and fading Lifetime warranty Bilstein and GMC A Tradition of Quality With over 15 years of experience with GMC Bilstein now offers shock absorbers specifically designed for the unique suspension of the GMC motorhome chassis Now you can have a new level of safety improved handl
12. 648 9858 for GMC Motorhome FAX and Voice Mail Any day at any time gmcmh aol com for GMC Motorhome E Mail Any day at any time on the Internet 650 948 8664 for GMC Motorhome Technical Assistance Monday through Friday 8 30 a m to 5 30 p m Pacific time Continued from Page 1 WC This manometer can be used to cal ibrate gauges and to directly check the pressure in an LP gas distribution system It can also be used to evaluate the system s performance and to check it for leaks Let s fill the manometer and check a GMC Motorhom system The exact amount of water put 3 LP gas distribution in the manometer is not important Just idd enough so there are six to eight inches in each leg Then find a centrally located pressure tap in your motorhome LP gas distribution system You may have to tee a tap into a line but a stove burner orific will do in older motorhomes that don t have a built in pressure reducing regulator A stove burner orifice can be used in all GMC Motorhomes that are still equipped with the original stove One screw usually removes a stove ind the burner inch plastic tubing will often fit leak free over the burner orifice without a clamp Position the manometer vertically so the water column heights in the legs of the U are equal prior to mak ing the connection Open the burner valve leading to the manometer and one other burner Light the open burner
13. AL amp SUNALLIANCE Subject Adapter Gasket Air Bag Longevity Air Bag Removal And Installation Procedure Air Bag Substitute Air Conditioning Maintenance Air Fuel Ratio Alcoa Part Numbers Alcoa Wheels Another Wiggle Wagon Battery Memory Bearing Specifications Bilstein Shock Absorbers Blower Resistor Blown Fuses Body Mounts Brake Fluid Brake Friction Material Braked Air Suspension Brakes Bridge Rectifier Campsite Amperage Carburetors Catalytic Heaters Chevrolet Guide Combination Valve Compressor Won t Pump Converters Coolant Temperature Cruise Control Dead Band Dead Batteries Dirty Compressor Drive Axles E Mail Electro Level I Voltage Engine Overheats Exhaust Leaks No 2 13 13 16 16 10 Issue Date Dec 1994 Sep 1997 Sep 1997 Jun 1998 Jun 1997 Mar 1997 Jan 1998 Mar 1997 Mar 1998 Dec 1995 Sep 1996 Dec 1997 Mar 1996 Dec 1994 Jun 1997 Dec 1996 Dec 1994 Sep 1996 Mar 1996 Dec 1996 Dec 1996 Mar 1995 Mar 1995 Dec 1994 Jun 1998 Sep 1997 Mar 1995 Dec 1995 Sep 1996 Mar 1995 Jan 1995 Sep 1997 Jun 1997 Mar 1996 Mar 1997 Mar 1998 Dec 1995 Issue Subject No Exhaust Manifold Gaskets 14 Final Drive 3 Final Drive Leak 8 Final Drive Lube 2 Fluid Leaks 7 Front Ride Height 2 Front Wheel Bearing Replacement 8 Front Wheel Bearings 8 Fuel Filter 12 Fuel Hoses 16 Fuel Starvation 1 Fuel Tank Selector Valve 10 Furnace Temperature 4 Fuse Block Deteriorat
14. Refrigerant Change Refrigerant Choice Refrigerator Choice Ride Height Issue No 11 13 16 13 15 6 16 11 8 6 o eeu Issue Date Mar 1997 Sep 1997 Jun 1998 Sep 1997 Mar 1998 Dec 1995 Jun 1998 Mar 1997 Jun 1996 Dec 1995 Sep 1996 Sep 1997 Dec 1997 Sep 1994 Jun 1996 Mar 1996 Sep 1995 Sep 1995 Jun 1998 Dec 1995 Sep 1996 Dec 1997 Sep 1994 Mar 1998 Sep 1997 Dec 1996 Mar 1995 Sep 1996 Sep 1995 Dec 1996 Dec 1994 Sep 1996 Mar 1995 Mar 1997 Sep 1996 Sep 1995 Mar 1995 Sep 1994 Issue Issue Subject No Date Subject Run On 5 Sep 1995 Surge And Backfire Sand In Bra 15 Mar 1998 Switchers Screwdriver Cam Out 15 Mar 1998 The Ladies Speak Sewer Odor 5 Sep 1995 Throttle Kicker Shiny Tires 16 Jun 1998 Time Delay Relay Shock Absorber Time Delay Longevity 1 Sep 1994 Relay Revisited Shower Drain 16 Jun 1998 Tire s Birthday Skinner Solenoid Valves 11 Mar 1997 Towed Vehicles Skirt Bracket 16 Jun 1998 Towing Sooty Vents 5 Sep 1995 GMC Motorhomes Speaker Wiring 4 Jun 1995 Transfer Switch Square Screwdriver 6 Dec 1995 Transmission Steering Boot 7 Mar 1996 Fluid Capacity Steering Box Leak 4 Jun 1995 Transmission Slipping Storage 14 Dec 1997 Transmission Vent Stuck Sender 2 Dec 1994 Turn Dimensions Suckin Air 14 Dec 1997 Two Speed Fan Issue Issue Issue Issue No Date Subject No Date 8 Jun 1996 Universal Carburetor 9 Sep 1996 4 Jun 1995 Water Heater 13 Sep 1997 Valve Leaks 13 Sep 1997 5 Se
15. air bag Over the years you have recommended against doing so for a number of reasons They include deterioration in storage leakage that isn t discovered until the warranty has expired storage space re quirement and others Instead of carrying a spare air bag you have suggested a number of blocks with lag s s and oth substitutes They include choc ends of rews threaded rods ence pi Can you be more specific Which substitute do you recommend Kevin McCarthy Ames lowa like the threaded rods best Kevin They Ter up very little space and allow you to adjust the rear ride height A GMC Zone Service Manager gave me a set in 1975 I have carried them ever since but have never used them That s another rea son not to carry a spare air bag along with the fact that the GMC Motorhome Parts Distribution Center can get one to you just about anywhere in North America in less than 24 hours The rods are X inch mild steel and they are a little over 18 inches long Both ends are threaded with X 16 SAE NF threads for about 2 inches A full size X16 nut is loosely installed on the end of each rod These nuts are used to support the con trol arms and adjust the rear ride height when the rods replace an air bag The rods are easy to install Simply re move the air bag and save the two jam nuts that hold the air bag in the control arms Make sure the full size nuts on the rods leave at lea
16. elping them out Reveon owners do not have a guardian angel comparable to Cinnabar Engineering Inc Bill Young Harrisonburg Virginia Because of your long association with Alexander amp Alexander I want to take this opportunity to personally ficial name change to RV The new organization will advise you of the company s Alliance America RVAA result in more than a name change Our motorhome customers are already noticing the improvements we ve made They include additional sales and service staff as well as improved telephone and systems technology Onur sales and service office is now located in Bellevue Washington Its toll free telephone number remains un changed at 800 521 2942 Brock Benn Senior Vice President RV Alliance America Clinton Township Michigan Terry Kane s shock absorber article in the March issue was one of the best feature articles you have published Gene Baguley Apple Valley California GMC MOTORHOME TELEPHONE NUMBERS amp TUSTIN Sw COLO 800 GMC TRUCK 800 462 8782 for Recall assistance and general information on GMC products Monday through Friday 8 00 a m to 5 00 p m Eastern time 800 720 CBAR 800 720 2227 for Genuine GMC Motorhome Parts and GMC Motorhome Operating and Service Publications Monday through Friday 8 00 a m to 5 00 p m Eastern time 810 648 2444 for GMC Motorhome Service Monday through Friday 8 00 a m to 5 00 p m Eastern time 810
17. embly with these accessories should be fastened to a body mounted bracket Then a flexible high pres sure hose with an excess flow POL Obviously this approach might be quite useful in bus The new Marshall Gas Controls Model 294 two stage LP gas pressure regulator has an excess flow POL adapter inlet It replaces most original LP gas regulators adapter should be used to connect the assembly to the conversions or large motorhomes and fifth wheel trailers that do not have a centrally located LP gas tank Perhaps the long known engineering advantages of two stage regulation were what motivated the code change Unfor tunately they were not used in the inter pretation of the code because a legitimate two stage regulator with two diaphragms and different input orifices didn t appear in the market until just recently Back in the early 1980s we tested sev eral of the new two age regulators and found they could not hold a candle to the quality single stage Rego 2403C9 that has been used in colder climates for years Many think the Rego 2403C9 is ically for a GMC Motorhome because it has a maximum too large not phys capacity rating of over 500 000 BTU However BTU maximum ratings are a has been a consolidation of regulator companies in recent years and Marshall Gas Controls introduced a legitimate twi stage regulator in the RV market about two years ago There are several confi
18. fold and branch pipe sizes are available in chart form at most LP gas dealers and they should be followed regardless of cost if you want trouble free appliance operation The LP gas tank valve is seldom defec tive However you can contribute to its longevity by not closing or opening it with too much force The valve is designed to close hand tight without wrenches and it should not be opened fully and forced counterclockwise because that stresses the gland Most manufacturers recommend opening it until it stops and then turning it back a bit This gives you a quick test of whether the valve is open The LP gas pressure can be adjusted with an ordinary screwdriver The system pressure is raised or lowered by turning the adjustment in the top of the regulator until the manometer reads 10 5 to 11 0 inches W and it eliminates stresses on the gland On the other hand a leaking tank valve is not something to be ignored That brings us down to the regulator which is probably the most neglected component in a motorhome from design as well as maintenance standpoints As the LP specifications clearly show the regulator as distribution system performance has a Herculean job to perform over considerable temperature range Unfortu nately the regulator in GMC Motorhome LP gas distribution systems was chosen with an eye only to cost and it is ignored by most owners Because unacceptable gas pressure
19. g place for the end with the vent cap at the side of the motorhome Once the other end of the hose is con nected to the elbow using the short piece of copper tubing and a little dishwashing soap to aid assembly the vent is perma nently extended and the hose will stay in plac U channel Any future fluid in the U expulsion will now be out of harm s way Leaking Windows Do you have any information on how to reseal the stationary side windows on my 1973 Canyon Lands They have moved forward al and there is a gap between al on all of the the edge of the glass and the side windows The gaps vary from just a little to as much as 4 of an inch They allow dust and water to get into the motorhome Ruth Higgs Bullhead City Arizona ou ve been parking your motorhome YY a downhill slope in the Arizona sun Ruth When a GMC Motorhome is parked in the sun it warms the glass and softens the adhesive that holds the sta tionary glass panels in place When this 3 1974 and 1975 models are parked front end down or 1976 1977 occurs and 197 and 1978 models are parked front end up the stationary glass panels will ooze in the direction of the motorhomes down ward slope creating the gaps you describe The solution is to park the motorhome on a level surface on a sunny day and let the glass get nice and warm Then take a block of wood and place it on the verti cal center mullion and use a hammer
20. gain for a long time What hose would be the smartest choice Chuck Boutell Arlington Heights Ilinois Cost increases nt auto parts stor ince I didn t have a copy of the SAE ia seat teed Chuck I called one of our hose suppliers He didn t have the SAE specifications either so he called Gates That company supplies most of his and many of our hoses The SAE 30R7 specification is for normal fuel hose The SAE 30R7 MXRI is not an SAE specification We think the MXR is a product date or cure code The SAE 30R9 specification is for high pressure furel injection hose Gates has two grades of 30R7 hose We buy the better grade because it seems to have more substance I cannot tell you whether it will last longer or not With respect to coolant hose we also buy the better grade for the same reason I guess we think it will last longer and as you say avoid a 5 to 10 year solution Alcoa Part Numbers Ive been in the market for a set of Alcoa wheels but everyone has a different price There weren t any part numbers in the March 1997 issue and I suspect my inability to compare may be different part numbers What are the correct part numbers for the GMC Motorhome hardware numbers Henry Davis Soquel California Also what are the correct here are many things that go into an Alcoa wheel price Henry Some companies are just brokers of the wheels Others are brokers of the wheels and
21. gu rations of the new Model 290 regulator and the one that is most commonly used 3MC Motorhomes is the Model 294 that has the top of the second stage rotat on ed 90 degrees clockwise so the vent on the second stage will point down when the assembly is mounted left to right like most original equipment regulators The Model 294 comes with an exc POL adapter that conforms to all of the s flow modern day codes The complete assem bly sells for about 25 The new Marshall Gas Controls two stage regulator assembly is about twice as long as the original equipment regulator vapor valve on the tank If only low pressure accessories are desired they can be fastened to a body mounted bracket and a fle sure hose can be used to connect them to cible low pres the regulator So build a manometer and test your LP gas distribution system at least onc k free but flunks any of the other tests or if you are concerned about year If it is le cold weather operation a new two stage regulator is a good first step If it still flunks after the regulator is installed you may have to upgrade your distribution system However first check the original pipes and hoses for kinks and obstructions 1984 issue of MotorHome magazine It was edited and updated for GMC Motorhome News and is reprinted with permission Motorhomes For Sale 1978 Royale 26 foot Rear Bath 48 000 Original Miles New Tires
22. hen it was new or last exposed to atmospheric pressure For the moment lets assume the ma nometer is steady Now light the furnace and watch the manometer A small drop in system pressure is normal but a drop approaching inch or more is not If the pressure drop is significant you could have the regulator difficulties mentioned above your LP gas distribution system s pipes may not be large enough or they may be kinked or obstructed Again for the moment lets assume the drop is small and the manometer stays steady Now turn off all gas consuming appliances and watch the manometer A rise in system pressure is normal but a rise approaching 1 inches or more is not Also the rise should be prompt and stop If the lock up pressure is 14 inches or more than the operating pressure the problems mentioned above are again likely If the pressure continues to rise the regulator is defective and should be repaired or replaced because such a condition may damage your appliances Also such a con dition may become dangerous because the excess pressure will ultimately be vented from the regulator and or the ap pliances even when they are turned off Once again lers assume that everything checks out and the pressure rises promptly and stops at a lock up pressure that is much less than 1 inches higher than the GMC Motorhome News gt Jun 1998 sasa Ia operating pressure Now go outside and turn off the LP
23. here and they come loose when the flange collapses This fact has been very costly to Ford and it is well known at Alcoa That s why Alcoa cautions against using any lug nut other than its lug nut Again it is Alcoa part number 139987 Once you have the Alcoa lug nuts and the longer GM stud bolts in the quote you are on your own Alcoa manufactures decorative hardware and a lot of people like it The center cap is Alcoa part number 003611 and the Hug A Lug nut covers are Alcoa part number 000190 There is also a lot of decorative hardware in the aftermarket As long as it doesn t compro mise the Alcoa lug nuts to hold it on the wheel some of it is worth considering Aftermarket decorative hardware pricing varies tremendously To get comparable quotes you need to write down what you need The list for most GMC Motorhomes should start with 6 or 7 Alcoa 160231 wheels 48 or 51 Alcoa 139987 lug nuts 48 GM 704922 stud bolts and decorative hardware of your choice Once you have prepared a list with part numbers most of the quotes will be within a few dollars of each other when freight and sales tax are considered and 1 O The Alcoa 139987 Lug Nuts and the GM 704922 Stud Bolts GMC Motorhome News June 1998 your choice will probably boil down to service after the sale which very few brokers provide Air Bag Substitute Just about every GMC Motorhome owner I know carries a spare
24. ing stability and control for your GMC motorhome with Bilstein gas pressure shock absorbers For additional information and a free brochure contact BILSTEIN CORPORATION OF AMERICA Sales West Sales East 8845 Rehco Road Wallingford CT MIA San Diego CA 92121 203 265 2854 619 453 7723 Onan out the connector can be seen at the lower right rear in the back of the compartment This connector is often the cause of the problem you describe It is not weath erproof but it is exposed to the weather which ultimately compromises its integrity The control wiring is relatively easy to find without a wiring diagram It is four white wires coming from the Onan They change to blue pink green and tan wires at the GM connector Once you have found the connector at the rear of the generator compartment pull it apart and clean its contacts If that doesn t restore its integrity eliminate it With insulated wire splices or replace it with a polarized weatherproof connector like a trailer wiring connector The wiring diagram for the control circuit is in the back of the GMC Motor home Maintenance Manuals X 7525 X 7625 and X 7725 It is shown on the Living Area 12 volt DC Electrical i tem diagram The control wiring is schemati cally shown in the X 7525 Maintenance Manual on pages 24C 47 and 48 Combination Valve In a discussion about the combination valve in the braking system in the GMC Moto
25. ion 12 Garage Door 4 Gasoline Leak 13 Gear Ratio 9 Gear Ratio Change 7 GM Fasteners 12 GMC Letters 12 Greasing 6 Greasing New Parts 15 Hard Start T Heater Hose Leaks 7 Heater AC Control 15 HEI Spark Plugs 10 Hitch Weight 5 Holding Tank 4 Hot Water Deposits 16 Hot Water Odor 14 House Batteries 4 HVAC Flow And Testing 8 Idiot Light Glows 10 Idiot Light Shines 15 Inconvenience Valves 1 Intermittent Ground 15 Inverter Chargers 7 Issue Date Dec 1997 Mar 1995 Jun 1996 Dec 1994 Mar 1996 Dec 1994 Jun 1996 Jun 1996 Jun 1997 Jun 1998 Sep 1994 Dec 1996 Jun 1995 Jun 1997 Jun 1995 Sep 1997 Sep 1996 Mar 1996 Jun 1997 Jun 1997 Dec 1995 Mar 1998 Mar 1996 Mar 1996 Mar 1998 Dec 1996 Sep 1995 Jun 1995 Jun 1998 Dec 1997 Jun 1995 Jun 1996 Dec 1996 Mar 1998 Sep 1994 Mar 1998 Mar 1996 s o ach Talk Index Issue Subject Inverter Chargers Kitchen Faucet Parts Leaking Windows Locking Gas Cap Loose Pulley Low Air Light Low Voltage Low Voltage Failures Lowering Problem LP Gas Leak LP Gas Leak Mark IV AC Shroud Microwave Oven Mismatch Hazard No Back Pressure No Heat Oil Consumption Oil Dilution Onan Control Open Diode Output Shaft Slop Overfilled Pork Chops Power Steering Fluid Filter Propane On The Road Propane Only Propane Sender Pulsating Water Pressure Quick Coupler Rafter Spacing Raise Won t Raise Rear Brake Adjustment Rear Hub Seal Recall Campaign 74 C 07
26. lk He could not get grease into his brand new lower ball joints Thad that problem and I also removed the Zerk fit tings to see if grease would travel through them It did so I concluded wrongly that the new joints must be tight and would work loose After reading your answer I took both grease nipples off and both of the base units had clearly bottomed out 1 took about 0 040 inches off the threaded faces and rein stalled them Now grease can be pumped in beautifully A simple solution to a potentially dangerous problem This shows the importance of attention to detail Mike Bond Roanoke Texas I just received my copy of the March issue Great idea including that big front page technical article on shock absorbers I really enjoyed it and hope to see more like it in the future Scott Woodworth Lemoore California With reference to Coach Talk in the March issue please inform Ms Debbie Bragg of Fort Worth Texas that if she is properly skirted she doesn t need a bra Dale Anderson New Lenox Illinois GMC Motorhome News is really the best The shock absorber article in the March issue was a revelation Larry Frear Aptos California I want to thank you on behalf of the many Reveon owners who have been referred to me by either you or one of your staff members Although I have absolutely no pecuniary interest in their purchase of parts from anyone and certainly am not in business myself I take pleasure in h
27. ne 1997 issue the arance between frame pads maintain cl the body and the frame When they fall out that clearance is lost and the fender skirts are compressed vertically This strains the upper and lower mounting points on the skirts Order a new 793494 Skirt Bracket along with a new 793495 Skirt and get Lamey Enterprises to replace your frame pads and body mounts on its new lift Then your fender skirts will quit breaking Broken fender skirts are just a manifes tation of the real problem The same is true for cracked manifolds and a number of other parts failures Replacing the broken parts often does not fix the real problem Onan Control I have a 6 kw Onan generator in my 1976 Palm Beach It works fine except it will not start with the interior switch It starts with the outside switch on the generator and can be shut off using the inside switch if it is not nun for over five minutes When L attempt to shut the Onan genera tor off inside after run ning it for awhile and warming it up it will act like the choke is applied and kick and buck Letting off the kill switch allows the generator to resume normal operation I m wondering if the circuit board is bad or maybe there is just a bad ground I do not have a wiring diagram and tried to run down the wires going to the inside switch with no The flexible portion of the skirt bracket arrow allows the skirt to move
28. ond regulator never sees more ince than 10 psi input much abused purchasing criterion because even cheap regulators for barbecue pits have rated capacities of over 100 000 BTU at 70 degrees F and that is why they are purchased with little thought given to their capacities at temperatures below freezing Most cheap regulators don t work worth a darn when all of the cooling variables gang up on them or when they are tested for lock up pressure Fortunately there on most GMC Motorhomes It can be cantilever installed in the vapor valve on the LP gas tank just like the original equipment regulator but popular acces sories like the Marshall Brass Extend A Flow and Extend A Stay or LP gas detector shut off solenoid valves should not be installed on the assembly without securing it to a tank mounted bracket The overall length of these accessories make the can pressure it can have a much larger ori fice than its single stage counterpart and that combined with less expansion across the orifice will make it consid erably less susceptible to regulator freeze up Additionally smaller pipe sizes can be used going from the first stage regulator to the manifold preceding the second stage zulator tilevered assembly too long for even mildly rough roads Since tank mounted brackets are almost impossible to install on original GMC Motorhome LP gas tanks a new two stage regulator as s
29. othing but soap and water on their products They say soap and water will keep tires clean but it won t remove the waxes and preservatives that protect the tires from the elements Waxes and preservatives are in synthetic rubber compounds and they work to the surface when the tires flex and get warm They are replenished when the tires are used and that s one of the reasons we recommend driving motorhomes 10 to 20 miles once a month to keep the tires and other vehicular components exercised Low Voltage Town a 1975 3 volt drop from the front of the motorhome to ganza II There is around a the rear lights and at the trailer hookup socket This makes the lights on my towed vehicle barely visible in daylight I have run a wire directly from the negative terminal of the vehicle battery to the rear of the motorhome and rechecked the voltage at each light using that ground The voltage does not improve which I think would rule out a poor or intermittent ground Where do I start looking for the voltage drop you well know the wiring is a nightmare to trace 1 assume the light switch is the starting point but that wouldn t have anything to do with the turn signals having low voltage Ben Mahoney Lexington Kentucky our known ground clearly shows cuit Ben Apparently you don t have a wiring diagram The G A wiring diagram makes finding the resistance a lot easier The diagram for your motorhome is in
30. out of the drain or off the drain with just a little back flow Do you know of any way to keep the con tents of the holding tank out of the bathroom when the holding tank is full We love to dry camp but we usually drive home in fear Mark Fernandez Santa Fe New Mexico s the shower drain A touch of the toe ope pe not Mark A plugged shower drain that will keep the contents of y our holding tank in the holding tank is avail able for your motorhome It is an inge nious replacement for the shower drain that was original equipment in all GMC Motorhomes With the exception of the center portion it even looks the same as the original The new drain has a thick metal disc in its center that is surrounded with an O ring seal The disc pivots open vertically with the touch of a toe and it closes flat with another touch of a toe When it is closed flat the drain is plugged equally in both directions It will not let fluid in or out in the closed position and it has been successfully tested on a number of GMC Motorhomes Should you want to remove the center disc the drain comes with a suction cup that will pull the disc out when it is in the A touch of the toe closes the shower drain closed position The disc will not come out in the open position for simple geometrical reasons Give it a toe and it open Give it another toe and it s closed It i
31. p 1995 Water Heaters 4 Jun 1995 9 Sep 1996 Water Leak 9 Sep 1996 Water Line Repair 12 Jun 1997 10 Dec 1996 Wheel Balance 9 Sep 1996 1 Sep 1994 Wheel Balance 15 Mar 1998 1 Sep 1994 Wheel Stud 2 Dee 1994 Wheels 1 Sep 1994 2 Dec 1994 Wiggle Wagon 6 Dee 1995 5 Sep 1995 Wiggle Wagons Revisited 7 Mar 1996 2 Dec 1994 Window Channel 10 Dec 1996 Replacement 6 Dec 1995 16 Jun 1998 Window Rattles 12 Jun 1997 3 Mar 1995 Wiper Blades 11 Mar 1997 15 Mar 1998 CiNNABAR ENG rS EER N G Inc GMC Motorhome Parts and Publications GMC Motorhome Service Center Remanufactured GMC Motorhomes Chevrolet Motorhome Service Center Certified Technicians 25 000 lb Lifts Exterior Paint Interior Renovation 6 wheel Alignment Collision Repair Inside Storage Motorhome Parts Service Publications 116 Orval Street Sandusky Michigan 48471 Sales amp Service 810 648 2444 Parts amp Publications 800 720 2227 uomp foyer Come visit our complete motorhome sales and service facility GMC Motorhome News March 1998 Continued from Page 4 tribution system The concept is not new either It has been used in home systems and some of the more expensive trailer systems for years The idea is to reduce the tank gas pressure to a manifold pres sure of 10 psi and then use a second reg ulator to reduce the manifold pressure to 11 0 inches WC for the appliance this sec
32. r mullion Track replacement is pic 3 and 1 9 tured and discussed on pages 1 of Maintenance Manual Slots must be cut in the bottom glass track for water drainage An X acto or a utility knife is used to cut the slots Skirt Bracket One of the 793495 Rear Fender Skirts on my 1978 Royale broke at the upper screw holes I installed it about a year ago The new skirt replaced a skirt that broke at the bottom We had the same skirts on our 1977 Royale and never broke one despite several flat tires Other GMC Motorhome owners tell me they have never broken a one of these skirts Is there something wrong with my skirt I don t look forward to having another one sanded primed and painted Jon Pickard Riverside California here is nothing wrong with your skirt Jon but there is probably some thing wrong with your skirt bracket and your body mounts and frame pads Body mounts and frame pads were discussed in the June 1997 issue The GMC Motorhome body moves independently of the frame The original equipment Skirt Bracket part number 793494 connects the skirt to the tandem axle mount through a piece of flexible material Many people don t understand the purpose of the flexible material and they replace the OEM bracket with a solid or semi solid bracket Such a bracket puts the skirt in jeopardy every time the motorhome hits a bump because the skirt is rigidly attached to the body As discussed in the Ju
33. regulation was found in many recreation vehicles the code was changed from sin gle stage to two stage regulators in 1978 Unfortunately our tests clearly show that two cheap regulators still do not equal The reasons for this are one good on quite simple The code became a market ing man s delight in that he could now sell two regulators per motorhome instead of just one In fact one manufac turer advertised positively that it was doubling up on its old single stage regu lator which supposedly made it better Since the first stage regulator only reduces tank pressure to 10 psi the rip off is clear because the first stage regulator will be fully open in extreme weathe nd you will be totally dependent on the old sin gle stage regulator when you ne most and it is least capable of performing There is a lot of merit to two stage v LP gas pressure regulation when it is properly engineered into an LP gas dis Continued on Page 14 C ach Talk by Wes Caughlan Fuel Hoses As I proceed to drop my fuel tanks I ve looked for fuel hose I find at least three SAE ratings so far and need advice on the correct one The cheapest is 30R7 rated hose next is 30R7 MXRI and a third one is 30R9 There are probably more but I found thes at three diffe _from 60 cents per foot to 90 cents and to 3 50 for the 30R9 I already bought the 30R7 but since I want to avoid a 5 to 10 year solution 1d like not to do this a
34. rhome a question came up Why do the rear brakes get 130 psi before the front brakes are applied We wondered if you could shed some light on this subject Thanks Chuck Garton Ridgecrest California eal simple Chuck If the rear brakes Rien go on first on a large vehicle that is rear end heavy it will fishtail Worse the rear end will come around and meet the front end jack knife Think of a larg bination with one or more trailers The truck and trailer com trailers hang on to the truck U Wes Caughlan is President of Cinnabar Engi neering Inc He is also a Consulting Editor of MotorHome magazine and writes the monthly Coach amp Chassis column in that publication E mail gmemh aol com The more things change The more they stay the same fter 32 years the Alexander amp Alexander While our name is changing the A amp A commit name is changing Our new name is ment to old fashioned personal service RV Alliance America we won t mind if you still continues What s in a name Find out for call us A amp A We think it says more about what yourself Call RV Alliance America today for we do offering RV owners the most compre a quote at 800 521 2942 hensive insurance products available anywhere RV Alliance America 800 521 2942 Business Hours PROGRESSIVE 11100 NE 8th Street Suite 900 FAX 800 598 9348 Monday Friday Bellevue WA 98004 4441 6 00 am 4 00 pm PST ssoneanow verce waunanct ROY
35. s MI 616 243 7323 Classified Advertisements 1977 Birchaven 23 foot Side Bath Completely Reconditioned Including Engine And Transmission Really Clean Loaded With Extras Always Garaged No Pets Or Smokers 25 000 Bill Butler Spirit Lake IA 712 336 2549 1976 Palm Beach 26 foot Side Bath 220 000 Original Miles But Runs Well Needs Fiberglass And Exterior Paint Good Remanufacturing Shell Located In Florida 7 500 Larry Freeman Morin Heights PQ Canada 514 226 5942 1976 Eleganza II 26 foot Side Bath Beige Imron Paint Rebuilt Engine And Transmission Inside And Outside Rebuilt With Original GM Parts 22 500 Chuck Drouillard Belleville MI 313 942 9224 Or 313 753 9326 1976 Eleganza II 26 foot Side Bath 67 000 Original Miles Original Paint And Interior Heavily Optioned Coach Many Upgrades Come Explore Alaska s Summer Beauty In A Classic 21 500 William Schilling Anchorage AK 907 230 7176 1976 Birchaven 23 foot Rear Bath 78 400 Original Miles New Paint Roof Rack And Ladder Pod CB Radio Good Condition Illness Forces Sale Call For More Information And Photos Dick McGuire Amarillo TX 806 1976 Palm Beach 26 foot Side Bath Recent Super Paint Scheme Carpet Drapes Michelins New Air Bags Toilet Shocks Sway Bars Steering Gear Steer ing Damper Wheel Covers Ladder Pod CB Microwave A Dream 22 000 Jerry Garner Livingston TN 931 823 2268
36. s GMC Motorhome part number 600510 The drain sells for 18 which is a small price to pay to eliminate holding tank fear I know because I used to drive home in fear too Shiny Tires L attended a motorhome rally recently and one of the participants recommended using brake ally He said it would clean them and make them look just fluid on tires and air bags periodi like new I have never heard of putting brake fluid in or on anything except a master cylinder for brakes There are a number of products in the market for cleaning rubber and plastics but none of them contain brake fluid Will brake fluid do the job Larry Frear Aptos California bsolutely not Larry In fact brake fluid may permanently damage tires and air bags and it should be washed off with soap and water if it is accidentally spilled or poured on them Whoever made such a recommendation obviously is unaware that no tire should be exposed to any petroleum distillate for any length of time Parking a motorhome tire in a puddle of oil or gasoline or brake fluid will permanently soften the rubber and lead to premature tire failure Periodically I get inquiries of this kind at MOTORHOME magazine because brake fluid will make tires shiny by softening and dissolving some of the rubber Such a practice apparently goes back to the days of natural rubber rather than modern day synthetic rubber tires Almost all of the major tire companies recommend n
37. s on the side of the transmission and the engine block Even if this is normal I am concerned about the potential fire hazard because the fluid eventu ally drips on the lefi hand manifold pipe What causes the expulsion Also what can be done to minimize the potential fire hazard Dave Erickson Roanoke Virginia here are a number of conditions that cause fluid expulsion Dave You have eliminated the most common one which is overfilling I suspect you are experienc ing excessive torque converter leakdown which gets worse with transmission age When a motorhome or an automobile sits for a few days the fluid in the torque converter gradually drains into the pan Tight fitting parts and the vacuum that develops in the torque converter retard this drainage but it increases with time and transmission age Normally this is nothing to cause concern because once the engine is started the pump in the transmission refills the torque converter and leaves a normal fluid level in the pan That s why jon fluid should always be checked when the engine is running And that s transmi why transmission fluid should be drained into a clean pan and measured when it is changed If the motorhome has been sit ting for a long time and the engine is not started before the transmission pan is taken down eight or nine quarts of fluid will drain from the par four quarts instead of the normal Transmission fluid expulsion
38. st one inch of the rod ends pro truding from each nut Jack the side of the motorhome until the control arms open sufficiently to in sert one end of the rod into one control arm and the other end of the rod into the other control arm When the rod is in both control arms lower the motorhome to proper ride height 8 to 8 inches under the end of the rear frame rail and loosely tighten the full size nuts against the con trol arm faces Then install the jam nuts and tighten them on the rods just like you would tighten them on the ends of a new air bag The rods will get you home or to the nearest campground Your ride quality won t be very good and you may have to drive slowly on rough roads but you won t be stranded in the middle of nowhere Hot Water Deposits Thave owned a 1974 Canyon Lands since 1977 when it was 10 000 mil enjoy every one of your articles in Coach Talk s new and I Shortly after purchasing the motorhome the original aluminum water heater perforated around a horizontal line about halfivay up the tank I don t think the previous owner ever had the water pump system working because ee _ Threaded rods take up very little space and they make excellent air bag substitutes we found plastic chips completely blocking a check valve that was between the fresh water tank and the water pump I replaced the water heater in October 1978 so it is now nearl
39. the U are the same prior to applying pressure Horizontal lines drawn on the board one inch apart or a measuring tape will measure the Continued on Page 3 GMC Motorhome News is published quarterly by Cinnabar Engineer ing Inc 116 Orval Street Sandusky Michigan 48471 TEL 810 648 2444 FAX 810 648 9858 gmcmh aol com Copyright 1998 by Cinnabar Engineering Inc All rights reserved Permission to reprint or quote excerpts granted only upon written request and then only when full credit is given source Subscription price United States Canada and Mexico 10 00 US per year All other countries add 8 00 Us per year First Class or Air Mail postage paid at Sandusky MI 48471 and at other mailing offices Wes Caughlan Editorial Director Lisa Yanagihara Ant Director Lorraine Graham Advertising Bill Estes Contributor Mad Macs Graphic Consultants GMC Motorhome News does not knowingly accept deceptive or misleading advertising or editorial material Ifyou have a contrary experience with respect to anything herein please contact Cinnabar Engineering Inc immediately The GM Emblem the GMC Emblem and the GMC Motorhome Parts Emblem are trademarks of General Motors Corporation and used under license to Cinnabar Engineer ing Inc LETTERS Once again you have come through with the solution This time it was the answer to Fred Heidner in the March Coach Ta
40. thing Works Excellent Condition 19 000 Located In Jackson MS 800 844 2000 Extension 2458 1973 26 foot Side Bath Rebuilt Brakes Air Suspension Clean 16 000 OBO Ben Appleby Southfield MI 248 559 8169 1973 26 foot Side Bath 89 000 Original Miles New Tires Stove Microwave Refrigerator And Captains Chairs Imron Paint 14 000 OBO Jack Salika Fernley NV 702 575 6210 GMC Motorhome News June 1998 1973 26 foot Side Bath 58 500 Original Miles Partially Restored New Michelin Tires And Chrome Wheels Death Forces Sale 11 000 OBO Sharon Rountree Bakersfield CA 805 836 8107 1973 Side Bath Fifteen Percent Restored New Parts Low Miles 18 000 OBO 616 842 7639 1973 Canyon Lands 26 foot Side Bath 78 000 Original Miles New Bilsteins Leveling Valves Brakes Mini Blinds Hitch 6 kw Onan 14 500 Darwin Gearhart Lakeland FL 941 859 7016 1973 Canyon Lands 26 foot Side Bath 103 000 Original Miles 50 000 On Engine New Tires LP Gas Refrigerator Upgrades Alcoa Wheels 17 500 OBO Tom Cherry Bakersfield CA 805 399 1400 AtWinterfeldt Parts For Sale Wanted 16 5 x 6 Chrome Wheels One or Two Needed For Radial Tires Fil Aguirre Tahoe City CA 530 583 6141 Parting Out 1977 Royale 26 foot Frame Sections Gas Tanks Body Sections Call For List Don Hauff Campbell CA 408 379 0440 After 6 PM Pacific Time Seven Original 1976 Radial Wheels Michelin XPS
41. to ntly drive the stationary glass back to its original position While you re at it take a look at the sliding window channel in your window frames General Motors issued a Service Bulletin in June 1975 75 IM 21 that affected all 1973 through 1975 side win dows and 1976 through 1978 driver and passenger windows It replaced the original channel that contained rusting wire with a flocked rubber channel The original part number was 702600 and the new part number is 2003071 The new flocked rubber channel comes in 25 foot sections or half sections for the driver and passenger windows It is cut to length and then measured for the location of the drain slots in the channel which don t always line up with the drain slots on the outside edge of the window frame A leather punch is used to perforate the new channel over the drain slots and it is then put in the window frame Weatherstrip adhesive keeps the new channel in place but only the ends need to be glued Don t over apply the adhe sive because you might want to remove the channel sometime in the future The large side windows in 1976 through 1978 models have plastic tracks for both the sliding glass and the screen The tracks come in 6 foot lengths and are part number 2004682 for the glass and 2004684 for the screen The exterior weather stripping is part number 009344 for the stationary glass 009842 for the sliding glass and 0102811 for the vertical cente
42. winter Gas pressure plus a number of other LP gas dis tribution system checks can be made using a sim ple U tube manometer that dates back to the 17th century when an Italian physicist named Torricelli learned that pressures could be accurately measured with a column of water Torricelli found that the diameter of the column was unimportant as long as it did not get too small and permit capillary action to bias its height The only problem with this form of pressure measurement was that it was cumbersome as pressures rose Fifteen psi is the equivalent of over 34 feet of water column and you would need a tall ladder to read it On the other hand when pressures are low or you desire to measure fractional psi pressures a crude water column of almost any diameter is a very useful tool and it is more accurate than even the finest gauges In fact such a water column is used to calibrate low pressure gauges and check them for accuracy The water column most commonly used as a by Wes Caughlan low pressure measuring tool is the U tube ma nometer It is a slight refinement of the original Torricelli column in that it is more compact and sier to use but it works the same Instead of Toricelli s single column the U tube manometer e has two vertical columns of the same diameter that oppose each other Initially the water columns in the legs of the U are the same height because the pressure on each column is the
43. y 20 years old My problem is that some white salts are coming through the hot water blocking fixtures and valves I presume this to mean that the anode has been completely sacrificed and it is time to buy a new water heater Please confirm this is correct before I go to the trouble The Hot Water Odor item in the December issue triggered this letter John Mack Laguna Beach California You water heater doesn t have an anode per se John The whole inside lining of the aluminum tank is the anode When it is gone the tank will soon per forate and leak The deposits you are experiencing may Which would mean the tank is not long for this world On the other hand they could be lime which is common in hot water tanks If the tank isn t leaking yet I would suspect lime Visit your local hardware or plumbing center to investigate products that will deal with lime Alternativ be aluminum oxid change your water source Lime calcium oxide comes from the water Shower Drain We live in fear Every time we dry camp in our 1976 Palm Beach we are afraid that the hold ing tank will overflow into the bathroom on the way home It happened once and we have lived in fear ever since It took forever to get rid of the awful smell We have purchased temporary plugs and have even used a sink pad on the way home Unfortunately almost every drain plug sold is designed to keep fluid in not out Most plugs come
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