2-5 GM:Layout 1 - Engine Builder Magazine
Contents
1. internal or external coolant leak To make the repair follow the upper intake manifold removal instructions found in the Engine Unit Repair section of the service information manual Refer to the arrow in the illustration of the upper intake manifold see Figure 2 below Inspect the inner diameter of the EGR passage for signs of material degradation Degradation will appear as pitting of the composite material in the EGR port pas sage If degradation of the upper intake man ifold composite material is found replace the lower and upper intake manifolds with the following part numbers Part Number Description 89017554 Gasket Kit Upper Intake Manifold 89017272 Manifold Kit Upper Intake 89017400 Gasket Lower Intake Manifold 24508923 Manifold Lower Intake Follow the lower and upper intake manifold installation instructions found in the engine unit repair section of the appro priate service manual If degradation is not apparent evaluate the vehicle for other causes of excessive coolant consumption as noted in the engine diagnosis section of the appropriate service manual GM 4 3L V6 Owners Rattled By Engine Noise From Torsional Vibration Some GM truck SUV and minivan own ers may complain about a rattle type noise coming from the engine area at approxi mately 1 800 to 2 200 rpm The rattle type noise may be caused by torsional vibration of the balance shaft Models most likely to be affected include2. 1996 2003 4 3L V6 engines found in Chevrolet Astro Blazer Express S 10 Silverado and P Models 1996 2003 GMC Jimmy Safari Savana Sierra Sonoma and 1996 2001 Oldsmobile Bravada applica 2 ENGINE BUILDER TECH SOLUTIONS GUIDE February 2010 tions To fix the problem follow this service procedure for installing a new tensioner assembly kit If detonation noise is present perform detonation spark knock diagnos tic testing first 1 Remove the engine front cover 2 Remove the crankshaft sensor reluc tor ring and line up the timing marks on the crank gear and camshaft gear 3 Remove the camshaft gear and chain For model years 1996 98 remove the crankshaft sprocket using a crankshaft sprocket removal tool p n J 5825 A or equivalent 4 Pull the shipping pin and discard Remove the nylon timing chain tensioner blade from the timing chain tensioner bracket 5 Position the bracket on the front of the engine The upper two attaching holes of the bracket will line up with the center two engine front cover bolt holes The lower bracket holes will line up with the engine front cover alignment holes see Figure 3 Figure 3 GM 4 3L lower bracket holes will line up with front cover alignment holes 6 Use a hammer and pin driver p n J 46165 or equivalent to install the dowel pins through the two lower holes in the bracket and into the engine block Make sure that the bracket is held firmly in place before proc
3. Always remember that not all guides in these cast heads are replaceable due to varia tions in the factory production methods This bulletin provided SB International courtesy of RAL M O Sheared Crankshaft Sprocket Keys Found on Some GM 6 2L Diesels This bulletin affects 1982 1989 GM light duty trucks G and H Vans with 6 2L diesel engines A new hardened washer p n 23504011 is available for improved clamp load of the crankshaft sprocket to the crankshaft by the crankshaft bolt Installation torques for the hardened wash er have been increased to 177 to 185 ft lbs 240 Nm 250 Nim Should damper loosening occur result ing in the crankshaft sprocket shearing the lead alignment key repairs should be made using the new washer and torque value Parts are currently available from GM and other suppliers Examine the crankshaft sprocket and determine before reassembly that there is no damage to the keyway During the assembly of the crankshaft sprocket to the crankshaft GM Goodwrench Thread Locker 272 p n 12345492 or equivalent should be applied to the crankshaft post for TORS Figure 7 The thread locking material should not be applied to the sprocket inside diameter but to the crankshaft post for 360 degrees at the rear crankshaft key area only 360 degrees at the rear crankshaft key area only Thread Locker 272 material should not be applied to the sprocket inside diam eter see Figure 7 above TSG
4. We Can D Any Ring Size 1 75 to over 10 Bores Sign up today at Hastingsmfg com for a FREE Tough Guy Racing Rings Wall Chart and New Applications e Newsletter HASTINGS HE ists 800 776 1088 hastingsmfg com sales hastingsmfg com Circe 105 for more information www enginebuildermag com ENGINE BUILDER 5
5. in the dif ferent type cylinder heads Aluminum cylinder head castings use the same guide for both intake and exhaust valves with the undercut on one end only On the other hand cast iron cylinder heads have an exhaust guide that is undercut on both ends and an intake guide that is undercut on one end only IMPORTANT For valve guides that are undercut on both ends insert the end of the that 6167 617 in diameter toward the combustion chamber If both ends of the valve guide measure the same diameter guide measures insert the end with less chamfer toward the combustion chamber 2 Remove debris from guide hole The guide hole must be clean for the new guide to seal the water passage 3 Insert the correct undercut end of the guide into the hole make sure that the correct end of the valve guide as instructed above points towards the combustion chamber side of the cylin der head The guide must be driven into the cylinder head from the same side as removed If the original guide was removed from the spring seat side the replacement guide must be installed from the spring seat side conversely if the original guide was removed from the combustion chamber side the replace ment guide must be installed from the combustion chamber side 4 Pressure test the cylinder head for leakage If water from the water passage leaks around the valve guide repeat removal and installation steps before dis carding the cylinder head
6. TECH SOLUTIONS GUIDE Revised Cylinder Head Torque Specs for GM 3 1L and 3 4L Engines 1994 2002 GM 3 1L and 3 4L engines require a revised Attention technicians cylinder head bolt torque and tightening sequence Be sure to follow this procedure for best results e Tighten the cylinder head bolts to 44 ft lbs 60 N m in the order shown in Figure 1 Use a torque angle meter p n J 36660 A or equivalent in order to rotate the cylinder head bolts an additional 95 degrees Figure 1 Follow this order to torque GM 3 1L and 3 4L heads to their proper specifi cations e Tighten the bolts in sequence to the specified torque With all the bolts tight ened make a second pass tightening all the bolts an additional 95 Remember 95 is just a little more than a 1 4 turn not 1 2 turn or from 12 o clock to 3 o clock on the dial Do not tighten beyond this speci fication otherwise the bolts will be over stressed and the gaskets may suffer damage Abnormal Coolant Consumption or Leaks in GM 3800 Series Il Engines Some installers may comment on excessive engine coolant consumption or an engine coolant leak near or under the throttle body area of the upper intake manifold on 1995 1999 GM 3 8L engines This leak Figure 2 Look for degradation of the upper intake manifold composite material may be related to upper intake manifold composite material that may degrade around the EGR stove pipe resulting in an
7. d the valve seat and pressure test the cylinder head If both a uniform seat width and leak free seal around the guide can be obtained then the original concen tricity was not a problem Also note that the exhaust valve guides are water cooled and have two difterent size press fit diameters Guide Removal 1 Measure and record the installed height above the cylinder head of the orig inal valve guide 2 First of all note that from model year MY 1985 GM has used a different method of sealing the water passages Unfortunately there is no known method to determine the size and type of guides in the cylinder head Drive the guide toward the spring seat approximately 0 250 6 35 mm Measure the guide s outside diameter closest to the spring seat If the guide s O D is 620 it is the old style guide Drive the guide out from the combustion chamber toward the spring seat it is the new style guide To remove this new style If the guide measures 616 guide perform the exact opposite proce dure mentioned above for removing the old style guide Drive the guide out from GENE the spring seat toward the combustion chamber CAUTION If the valve guides are removed in the wrong direction the head may be damaged which may result in water leakage into the combustion chamber as well as offset seat to guide concentricity Guide Installation 1 Make sure the correct guide is being installed when replacing a guide
8. eeding Figure 4 Figure 4 Use a hammer pin driver to install the bracket dowel pins in the engine block Figure 5 Position top of guide under tab bracket 7 For model years 1996 98 install a roller type timing chain set Install the crankshaft sprocket using the J 5590 crank shaft gear installer Install the timing chain around the crankshaft sprocket and position the timing chain to the driver s side of the engine 8 Install the nylon timing chain ten sioner guide onto the timing chain ten sioner bracket pin and position the top of the guide under the tab at the top of the bracket see Figure 5 above 9 Install the camshaft sprocket into the chain and then to the camshaft Install the bolts finger tight Make sure the timing marks are aligned then tighten the camshaft sprocket bolt Tighten the bolt to Figure 6 Tighten bolts to 106 in Ibs 18 ft lbs 25 Nm 10 Install the crankshaft reluctor ring 11 Install the engine front cover and place a washer under the two center cover bolts that extend through the tensioner bracket These washers are required to maintain the proper crush on the engine front cover seal see Figure 6 above Tighten the bolts to 106 in Ibs 12 Nm PARTS INFORMATION Part Number Description 12458911 Chain Kit 89017257 Tensioner 10220906 Oil Pan Gasket 88893989 O Ring and Gasket Kit 3754587 Water Pump Gasket 2 89017259 Cover UNITED MACHINE COMPANY Sil
9. volite Over 485 OE replacement pistons for auto light trucks popular imports and heavy duty applications Coated skirts Floating wrist pins where applicable Application specific aluminum alloys www uempistons com CALL 800 648 7970 1040 Corbett St Carson City NV 89706 United Engine amp Machine Co S Better Pistons Since 1922 Circle 104 for more information 4 ENGINE BUILDER TECH SOLUTIONS GUIDE February 2010 Revised Connecting Rod Bolt Torque Specifications For GM Vortec V8s When working on 1997 2008 Gen II and Gen IV Vortec 4 8L 5 3L 5 7L 6 0L and 6 2L V8 engines you should follow a new connecting rod bolt torque specification The rod bolts should continue to be tight ened using two passes The new specification calls for the sec ond pass value to be increased from 75 to 85 degrees following this procedure 1 Tighten the connecting rod bolts a first pass to 15 ft lbs 20 Nm 2 Tighten the connecting rod bolts a final pass to 85 degrees using an angle meter J 45059 Installing Exhaust Guides in 366 396 cid and 427 454 cid GM Big Blocks Because of GM s factory production method of placing the valve guides in the head castings after the cylinder head was cast original valve guides may not be con centric or parallel to the outside diameter They also may not be replaceable The only practical method to deter mine if this is a problem is to install a new guide grin
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