Home
Power Steering Troubleshooting Procedures
Contents
1. The numbers below correspond to the steps in the troubleshooting procedures Subject 300 Refer to Subject 300 for definitions explanations and instructions 1 Check tire pressure and load Front tire pressure correct and even on both sides o Yes o No Rear tire pressure correct and even on both sides o Yes o No Oversized front tires o Yes o No Operated at excessive load o Yes o No 2 Check fifth wheel lube and condition o N A o OK o Not OK 3 Check for loose and binding components Lubrication of drag link tie rods and knuckle pins o Yes o No Steering driveline Uoints bind o Yes o No Sector shaft adjustment OK o Yes o No Front tire self retun OK o Yes o No Fasteners and components worn or loose a Yes o No 4 Power steering temperature and hydraulic checks 4 2 Check for correct fluid level o Fluid OK o Added fluid 4 5 Record initial fluid temperature oF oS 5 Power steering hydraulic system Install a Power Steering System Analyzer PSSA between the pump high pressure line and the steering gear Run the engine at idle and use the load valve to raise the fluid temperature to 180 F 82 5 1 Recordtotal system back pressure opsi okPa See troubleshooting and diagnostic checks if greater than 100 psi 689 kPa SD 94 9 17 04 02 22 2008 020157 Fig 1 Checklist for Troubleshooting Power Steering System Performance Front Page 300 2 Heavy Duty Trucks Service Manual Supplement 32 Januar
2. Maximum Allowable Restriction Action to Take P2 total system pump outlet Hydraulic brakes 140 psi 965 kPa Air brakes 100 psi 689 kPa Check pressure at the key locations P2 G1 hose pump to gear 12 psi 83 kPa Check for a kinked or plugged hose Replace the hose if necessary G1 G2 steering gear 55 psi 379 kPa The gear rotary valve is damaged Replace the gear See instructions elsewhere in this group G2 B1 hose gear to booster 12 psi 83 kPa Check for a kinked or plugged hose Replace the hose if necessary G2 R1 hose gear to reservoir 12 psi 83 kPa Check for a kinked or plugged hose Replace the hose if necessary B1 B2 booster 40 psi 276 kPa Check the internal booster filter for contaminants Check for contaminants causing binding or blockage of poppet and check valves within the booster B2 R1 hose booster to reservoir 12 psi 83 kPa Check for a kinked collapsed or plugged hose Replace the hose if necessary R1 R2 reservoir 2 qt 4 psi 28 kPa Replace the filter Check for internal blockage R2 P1 hose pump supply 12 psi 83 kPa Check for a kinked collapsed or plugged hose Replace the hose if necessary Table 5 Total System and Component Restrictions 300 12 Heavy Duty Trucks Service Manual Supplement 32 January 2006 Power Steering Troubleshooting Procedures 46 17 T
3. as re e Partially close the load valve on the Tuo oy re e Dat Tick PSSA until the pressure gauge Beat Man t Are n Ari 2 reads 1000 psi 6895 kPa ervice Manual ter replacing the pressure relief valve repeat sub e Open the valve when the fluid tem steps 5 1 and 5 2 Make sure the perature reaches about 180 F temperature is at about 180 F 82 C 82 C If the pressure was consis 5 Test the power steering hydraulic system tent go to substep 5 3 5 3 Check the pump relief pressure e Slowly close the load valve e When the valve is completely closed read the pressure gauge 5 1 Check the total system back pressure e Run the engine at idle e Make sure the PSSA load valve is fully open e Read the pressure gauge on the PSSA e Record the total system back pres sure on form SD 94 e Open the valve Heavy Duty Trucks Service Manual Supplement 32 January 2006 300 5 46 17 Power Steering Troubleshooting Procedures Troubleshooting Procedures Minimum Measured Pump Flow and Relief Pressure at Engine Idle Gear Make and Model Flow at 1800 psi 12 500 kPa TYpical Relief TRW TAS40 or HFB52 1 8 gpm 6 8 L min TRW TAS55 2 2 gpm 8 3 L min TRW TAS65 or HFB64 2 6 gpm 9 8 L min TRW TAS85 or HFB70 3 2 gpm 12 1 L min TRW TAS65 With RCS65 5 6 gpm 21 1 L min TRW TAS65 With Linear Cylinder 6 1 gpm 23 1 L min TRW TAS85 With RCS65 6 6 gpm 25 0 L min 217
4. f the tire does not return to near straight ahead check for binding or a lack of lubrication in the steering axle kingpin bushings or tie rod link age 3 2 Check the COE steering column bearings e Connect the drag link and tighten for binding Lubricate them if needed the castle nut then install a new 3 3 Check the steering driveline U joints for cotier pin looseness or binding Lubricate them if 3 7 Inspect all suspension fasteners and com needed ponents for wear and looseness 3 4 Check for correct steering phasing where Prepare the power steering system for tempera applicable The U joints should line up ture and hydraulic checks Reset the phasing if needed NOTE The hydraulic power steering system NOTE On older COEs the steering is tested with a Power Steering System Ana U joints do not line up lyzer PSSA and with the hydraulic fluid at 6 Check the scion Shale aduaimenk operating temperature The part number for the PSSA is J 26487 The part number for e Muli ine vehicle On the ground and the adapter kit is J 28593 The PSSA and the front tires pointed straight adapter kit are available from SPX Kent ahead turn the steering wheel until Moore See Fia 3 slight motion is observed at the front oem wheels A PSSA is a combination of a flow meter a e Align a reference mark on the steer shutoff valve and a pressure gauge The ing wheel toa rule then slowly turn PSSA will allow you to measure flow and t
5. fitting leaks Add fluid if needed If there is air in the fluid check for inlet tube and hose leaks Correct all leaks A change from the usual pump sound Check the power steering fluid reservoir Check for air bubbles and foam in the fluid If there is air in the fluid check for inlet tube and hose leaks Correct all leaks Clicking noise during a turn Check for loose steering components Check the front suspension for insufficient spring pin shims Tighten any loose steering components Add front spring pin shims if needed Hissing when the steering wheel is at or Fluid flowing past a poppet valve makes a hissing noise This is normal No near full turn action is needed Table 3 Power Steering System Noise Power Steering Pump Noise Possible Cause Remedy The intake line is plugged Drain the system Clear the intake line if needed Fill the system There is an air leak at the pump Check all the connections by pouring power steering fluid over them and connections the fittings the reservoir listen for a reduction in sound Tighten all the connections as needed If the connections or the shaft seal problem persists remove the pump disassemble it and replace the shaft seal The pump input shaft is misaligned Remove and disassemble the pump Replace the shaft seal and bearing Table 4 Power Steering Pump Noise e Indicate on form SD 94 if there were e Run the engine at idle and check for any
6. following test Make sure that the spacer block contacts the axle stop squarely Contact that is not square could break the stop bolts or eject the spacer block which could cause serious personal injury CAUTION While running the following test do not hold the steering wheel in the full turn position for more than five seconds Doing so could damage the pump NOTE The following substeps check for ex cessive internal leakage in the steering gear s Make sure the fluid temperature is Power Steering Troubleshooting Procedures approximately 180 F 82 C and the vehicle is stationary with the front wheels pointing forward 5 9 Test the steering gear internal leakage e Run the engine at idle with the load valve open e Place an unhardened steel spacer 1 inch 25 mm thick between the axle and the stop bolt at one side of the axle See Fig 4 The spacer should have an exten sion or handle long enough to keep fingers clear of the axle stop area A brazing rod or welding rod works well for this purpose 7 03 10 94 f460608a Fig 4 Position the Steel Spacer e Have someone turn the steering wheel until the stop bolt contacts the spacer block See Fig 5 e Apply a 20 pound 89 newton force on the steering wheel e Read the internal leakage rate on the flow meter Record this value on form SD 94 300 8 Heavy Duty Trucks Service Manual Supplement 32 January 2006 46 17 Power
7. 5 100 psi TRW TAS85 With Linear Cylinder 6 1 gpm 23 1 L min 15 000 700 kPa HFB70 With RCB70 6 6 gpm 25 0 L min HFB70 With RCB64 6 1 gpm 23 1 L min HFB70 With Linear Cylinder 6 1 gpm 23 1 L min Sheppard MD83 2 1 gpm 8 1 L min Sheppard M100 3 0 gpm 11 4 L min Sheppard M110 With Slave 110 and Dual TRW Right Side Rams 5 6 gpm 21 2 L min On vehicles with TRW TAS steering gears and hydraulic brakes the typical relief pressure is 2375 100 psi 16 000 700 kPa Table 1 Minimum Measured Pump Flow and Relief Pressure at Engine Idle Minimum Measured Pump Flow and Relief Pressure for High Pressure Gears at Engine Idle Gear Make and Model Flow at 2300 psi 16 000 kPa LL shana TRW THP45 1 5 gpm 5 7 L min TRW THP60 or PCF60 2 3 gpm 8 7 L min 2683 100 psi TRW THP60 With Linear Cylinder 5 8 gpm 22 0 L min 15 000 700 kPa TRW THP60 With RCH45 6 3 gpm 23 8 L min Table 2 Minimum Measured Pump Flow and Relief Pressure for High Pressure Gears at Engine Idle e Record the relief pressure on form If the pump relief pressure does not SD 94 match the relief pressure in Table 1 or Table 2 or the pump manufactur er s specifications replace the pres nae sure valve if not done previously or eae ene acceptable Go to the replace the power steering pump p After replacing the pressure relief If the pump relief pressure does not valve in the pump repeat substeps match the relief press
8. Note the pressure gauge reading e Repeat the previous three instruc tions for the opposite turn e Record the poppet relief pressure on form SD 94 for both turns The pressure should drop slightly before the steering stops are con tacted If the pressure increases from contact with the steering stops the poppets plungers must be manually reset For poppet reset instructions see the Heavy Duty Trucks Service Manual If the pressure is relieved and assist is lost when the wheel is too far from the axle stop adjust the auto matic poppet valve following the in structions in the next substep rect poppet adjustment and must be replaced After poppet replacement and adjustment test again for cor rect poppet relief function and record the pressure on form SD 94 7 Check for abnormal power steering noise NOTE Noise from the power steering sys tem does not necessarily mean there is a problem Some noises are normal and are the result of proper operation fal 7 2 7 3 If not already done check for proper fluid level Record the results on form SD 94 Check the condition of the power steering fluid and record the condition on form SD 94 Check if a hissing sound is heard at less than full turn If a hissing sound is heard check the steering gear poppet and the axle stop adjustment and record the result on form SD 94 For adjustment instruc tions see step 6 See Table 3 and Table 4 for possible ca
9. Power Steering Troubleshooting Procedures General Information A new Checklist for Troubleshooting Power Steering System Performance form SD 94 has been devel oped to include the new high pressure power steer ing gears as well as the power steering pumps Use form SD 94 dated 9 17 04 and the following trouble shooting procedures when troubleshooting the power steering system You are required to fill out the applicable sections of form SD 94 when submitting a warranty claim on a power steering gear It is recommended that you fill out the applicable sections of form SD 94 when sub mitting a warranty claim on a power steering pump See Fig 1 and Fig 2 for a sample of form SD 94 Form SD 94 can be downloaded from the internet through www AccessFreightliner com e Key in your user name and password e Click on Applications e Click on ServicePro e Cancel the Vehicle Identification window e Click on Service Solutions e Click on Symptoms Search e At the bottom of the screen enter 2005 in the Enter Solution Number field e Click on the SD 94 attachment Dealers can order form SD 94 through the TAO elec tronic mail system e At the TAO Mail Menu key in B for bulletin boards e Tab down to Pub Forms FTL and key in L for list e At Freightliner Manuals Order Form key in U If you don t have access to the TAO electronic mail system contact Publishing Distribution at 503 745 7343 Troubleshooting
10. Procedures Steps 1 through 3 are typically related to routine maintenance procedures Some of these inspections and procedures can be found in the Pretrip Inspec tion and Daily Maintenance chapter in the FLD Con ventional Driver s Manual some of these inspections 46 17 Troubleshooting Procedures and procedures can be found in the Heavy Duty Trucks Maintenance Manual 1 Check the tire pressure and load 1 1 Check that the front tires are inflated to the correct pressure and the tire pressure is equal on both sides Correct the pres sure if needed Low pressure causes increased steering effort due to friction with the road surface Unequal tire pressure causes unequal fric tion between the tire and the road This can cause pulling to one side Check the tires for damage or abnormal wear 1 2 Check that the rear tires are inflated to the correct pressure and the tire pressure is equal on both sides Correct the pressure if needed 1 3 Check that the tire sizes are correctly matched and whether duplex or oversized tires that were not originally specified for the vehicle have been installed Extra tire width causes increased steering effort due to extra friction with the road surface If the axle stops were turned out to reduce wheel cut due to a change in tires the power steering gear poppets plungers will need to be adjusted 1 4 Determine whether the vehicle is operated at or over the rated load Incre
11. Steering Troubleshooting Procedures 03 10 94 f460601a Fig 5 Steel Spacer Contacting the Axle Stop e Repeat substep 5 9 beginning with placing the spacer between the axle and the axle stop for the opposite turn The maximum permissible internal leakage for a single gear is 1 0 gom 3 8 L min If leakage is greater in either turning direction replace the steering gear components as needed For systems with two or more steer ing gears and or linear cylinders the total acceptable internal leakage is 1 0 gpm 3 8 L min for each steer ing gear ram in the system For ex ample for a dual gear system two steering gears the total acceptable internal leakage is 2 0 gpm 7 6 L min If the leakage is more than 2 0 gpm 7 6 L min on a dual gear system isolate the auxiliary cylinder from the system Disconnect the auxiliary cylinder hy draulic lines at the main gear auxil iary ports Troubleshooting Procedures e Plug the main steering gear ports with suitable steel or high pressure plugs or caps e Direct the disconnected lines into a drain pan e Repeat the internal leakage test If the internal leakage is less than 1 gpm 3 8 L min repair or replace the auxiliary gear or linear cylinder If the internal leakage is greater than 1 gpm 3 8 L min repair or replace the main gear e Remove the plugs and connect the hoses e Fill the power steering reservoir to the proper level 6 Che
12. ased load causes greater steering effort Make sure the vehicle is being op erated within rated capacities 2 Check the lubrication and condition of the fifth wheel if so equipped Check to see if the fifth wheel is adequately lu bricated A dry fifth wheel plate makes it difficult to change direction Check the plate surface for burrs gouges and irregularities 3 Check for loose and binding components Check whether any steering components need mainte nance or adjustment 3 1 Check for proper lubrication of the drag link tie rods and knuckle pins Apply lu brication as needed Heavy Duty Trucks Service Manual Supplement 32 January 2006 300 1 46 17 Power Steering Troubleshooting Procedures Troubleshooting Procedures FREICHIUINET Checklist for Troubleshooting A DaimlerChrysler Company Power Steering System Performance To be used with the troubleshooting and diagnostic checks Date Work order No Evaluation paformed by o Dealership o Fleet o Independent Vehicle Vehicle model Serial No Date in service Identification Mileage Mileage when steering complaint first occurred Vehicle application Normal steering axle load Steering Steering pump mfr Model No System Description Steering gear mfr Model No Date code Slave steering gear mf optional Mocel No Date code Reservoir capacity o 2 quarts 1 9 liters o 4 quarts 3 8 liters Type of fluid o ATF o Other List complaint
13. cessive Go to step 8 to find the restric 4 5 Determine the initial power steering fluid tion in the system temperature e Place a temperature gauge in the A CAUTION fluid reservoir Do not leave the load valve closed for longer than five seconds during the following test Doing so could damage the power steering sys e Record the initial temperature on form SD 94 and leave the tempera ture gauge in the reservoir to moni tor the fluid temperature throughout tem these tests 5 2 Check for erratic pump response NOTE Power steering system checks must e Slowly close the load valve be done with the power steering fluid at op e When the valve is completely erating temperature approximately 180 F closed read the pressure gauge 82 C Maintain this temperature throughout Oneni the following tests po TAS TEE If the pressure rises rapidly appears A CAUTION to be uncontrolled or rises above the typical relief pressure open the Do not leave the load valve fully closed for load valve immediately See Table 1 longer than five seconds Doing so could damage or Table 2 for relief pressures the power steering system e Indicate on form SD 94 whether the 4 6 If not already done raise the power steer pump response was erratic or not ing fluid temperature to normal operating If the response was erratic replace temperature the pressure relief valve in the pump e Run the engine at idle or the power steering pump
14. ck the steering gear poppet relief valve and stop bolt adjustment NOTE Poppets limit the steering assist when the front wheels approach the stop bolts Improper adjustment can apply exces sive force to the steering linkage or loss of assist as the steering wheel approaches ei ther full left or full right turns 6 1 Check the steering system for adequate turn angle e Make sure the stop bolt settings limit the steering travel so there is 1 2 inch 13 mm clearance from all sta tionary components and 3 4 inch 19 mm clearance from all moving components e Make sure the pitman arm is situ ated on the steering gear sector shaft correctly A CAUTION If power steering pump relief pressure is reached while the steering wheel is at full lock release the steering wheel from this position Do not allow the pump relief pressure to be maintained for longer than five seconds or damage to the pump may result 6 2 Check the poppet relief pressure Heavy Duty Trucks Service Manual Supplement 32 January 2006 300 9 46 17 Power Steering Troubleshooting Procedures Troubleshooting Procedures e Set up a system for hydraulic checks as done in step 4 e Make sure the fluid temperature is at approximately 180 F 82 C and the vehicle is stationary on the ground with the front wheels point ing forward e Run the engine at idle with the load valve open e Turn the steering wheel to either full lock position e
15. he steering wheel in the opposite pressure and provide a load on the pump in direction until motion is again de the hydraulic lines of the steering system Polea aries Wies 4 1 Park the vehicle outside to reduce noise e Measure the lash free play at the and exhaust in the shop rim of the steering wheel Excessive lash exists if steering wheel movement exceeds 2 1 2 inches 64 mm with a 20 inch 508 mm steering wheel or 2 1 4 inches 57 mm with an 18 inch 457 mm steering wheel x 3 6 Check that the front wheels self return i without binding Bay e e With the engine off chock the rear 7 most tires and place the front tires on radius plates turntables e Disconnect the drag link from the 03 10 94 f580010a steering arm ER nal e By hand pull the tire to one axle gel REO SE ER stop and release The tire should 4 2 Record on form SD 94 whether the fluid self return to almost straight ahead level was okay or if fluid was added e Repeat in the opposite direction 300 4 Heavy Duty Trucks Service Manual Supplement 32 January 2006 Power Steering Troubleshooting Procedures 46 17 Troubleshooting Procedures 4 3 Install the PSSA between the pump high NOTE If the total system back pressure is pressure line and the steering gear greater than 100 psi 689 kPa on a vehicle with air brakes or 140 psi 965 kPa ona 4 4 Fill and bleed the steering system as A vehicle with hydraulic brakes back pressure needed se is ex
16. k pressure 8 1 Check for kinked or collapsed hoses o Yes o No 8 1 Check for leaking fittings o Yes o No 8 1 Check for leaking seals o Yes o No 8 2 Install a low pressure gauge 200 to 300 psi 1379 to 2068 kPa in the appropriate locations within the power steering system to determine the following values 8 3 Fill out the fields below using instructions found in substep 8 3 of the diagnostic checks Pump outlet P2 P2 max 100 psi 69 kPa o OK o Not OK 140 psi 965 kPa o OK o Not OK Gear inlet G1 P2 G1 max 12 psi o OK o Not OK Gear outlet G2 G1 G2 max 55 psi o OK o Not OK Booster inlet B1 G2 B1 max 12 psi oOK oNot OK Booster outlet B2 B1 B2 max 40 psi o OK o Not OK Reservoir inlet R1 B2 R1 max 12 psi o OK o Not OK Reservoir outlet R2 G2 R1 max 12 psi o OK o Not OK Pump inlet P1 R1 R2 max 4 8 psi o OK o Not OK R2 P1 max 12 psi o OK o Not OK For vehicles with hydraulic brakes List repairs and add comments SD 94 9 17 04 02 22 2008 020158 Fig 2 Checklist for Troubleshooting Power Steering System Performance Back Page Heavy Duty Trucks Service Manual Supplement 32 January 2006 300 3 46 17 Troubleshooting Procedures Chock the rearmost tires With the engine shut down turn the steering wheel and check for looseness or binding Make sure all components are free to move but are not excessively loose Power Steering Troubleshooting Procedures e
17. kinked or collapsed hoses or correct fluid level If necessary add leaking fittings or seals fluid If bubbles or foam appear in the reservoir check the hose fittings If you replaced the steering gear forlo seness or leaks input shaft seal and found it to be excessively hard test the system e With the engine at idle read the operating temperature substep 5 8 total system back pressure on the if not already done pressure gauge Record the value on form SD 94 A CAUTION e f the total system back pressure is greater than 100 psi 689 kPa or Do not move the steering wheel or allow the sys 140 psi 965 kPa for a vehicle with tem pressure to exceed the rating of the gauge hydraulic brakes go to the next sub during the following test or damage to the gauge step If the pressure between the could occur pressure line and pump is less re 8 2 Test the system back pressure striction is not a problem e Install a low pressure gauge 200 to 8 3 Determine the restriction of the individual 300 psi 1379 to 2068 kPa components by subtracting the values maximum between the pressure shown in Table 5 Record the values on line and the pump form SD 94 Heavy Duty Trucks Service Manual Supplement 32 January 2006 300 11 46 17 Power Steering Troubleshooting Procedures Troubleshooting Procedures The component at fault can be identified by checking pressure at key locations in the steering system With the e
18. mp or replace the power steering pump as re quired For instructions see Group 46 in the Heavy Duty Trucks Service Manual CAUTION Do not allow the temperature to exceed 250 F 121 C during the following test If this tempera ture is exceeded stop the test and record the last noted temperature on form SD 94 5 8 Record the maximum fluid temperature e Run the engine at governed speed Heavy Duty Trucks Service Manual Supplement 32 January 2006 300 7 46 17 Troubleshooting Procedures e Observe the power steering fluid temperature until it stabilizes e Record on form SD 94 the maxi mum power steering fluid tempera ture If the temperature does not exceed 250 F 121 C during the test ex cessive system heat is probably not the cause of the complaint If at any time during the test the temperature exceeded 250 F 121 C the system is operating at excessive temperature levels and steering system performance and life may be affected Damage to hoses seals and other components may result if the vehicle is operated at excessive steering system tem peratures Excessive steering system back pressure or excessive pump flow may be the cause of the over tem perature problem Go to step 8 if you suspect a restriction in the sys tem If excessive heat continues to be a problem a cooler may need to be added to the system Keep fingers clear of the stop bolt and spacer block during the
19. ngine at idle use the low pressure gauge and hose connection adaptors necessary to mea sure pressure at all locations identified in Fig 6 Each time the gauge moves to a new location make sure that the fluid level is correct and air is removed from the system by running the engine at idle and checking the fluid level e Install the low pressure gauge be tween the pump outlet and the pump to gear hose Record this value as P2 e Install the low pressure gauge be tween the pump to gear hose and the steering gear inlet port Record this value as G1 e Install the low pressure gauge be tween the steering gear outlet port and the gear to reservoir hose Record this value as G2 e Install the low pressure gauge be tween the gear to reservoir hose and the reservoir inlet port Record this value as R1 e Install the low pressure gauge be tween the reservoir outlet port and the reservoir to pump hose Record this value as R2 e Record the total system back pres sure as determined in substep 8 2 as P1 NOTE For a vehicle with hydraulic brakes perform similar procedures as those in substep 8 3 Record the pressure at the booster inlet as B1 and at the booster outlet as B2 If any component exceeds the maxi mum allowable restriction listed for each component refer to the appli cable action to take in Table 5 Total System and Component Resirictions Total System and Component Pressure Check Location
20. roubleshooting Procedures 1 G1 an P2 2 B1 B2 P1 G2 3 R1 R2 E A Fr q 4 1 GA P2 2 P1 D G2 R1 R2 g B 08 22 94 f460611a A For Vehicles With Hydraulic Brakes B For Vehicles With Air Brakes 1 Steering Pump 3 Brake Booster 2 Steering Gear 4 Reservoir Fig 6 Plumbing Diagrams 300 13 Heavy Duty Trucks Service Manual Supplement 32 January 2006
21. te the flow rate with the load valve open e Close the load valve until the pump relief pressure is reached e Smoothly and quickly open the load valve and note the flow rate Repeat this action three times It should re turn to the flow rate noted above e Record on form SD 94 whether the relief valve operated correctly at 1500 rpm If the flow rate returns immediately the relief valve is acceptable Go to the next step Troubleshooting Procedures If the flow rate does not return im mediately the pump relief valve is not working correctly Replace the relief valve if not done previously 5 6 Test the flow of the pump at idle with a load applied e Run the engine at idle e Slowly close the load valve until the pressure gauge reads 1800 psi 12 410 kPa e Read the flow gauge and record the flow rate on form SD 94 NOTE For high pressure steering gears use 2300 psi 15 858 kPa as the test load pressure See Table 1 or Table 2 for minimum flow rate e Open the load valve 5 7 Test the maximum flow of the pump with no load applied e Run the engine at 1500 rpm e Read the flow gauge and record the maximum flow on form SD 94 If the flow rate is below the mini mum as indicated in Table 1 or Table 2 repair or replace the pump For instructions see Group 46 in the Heavy Duty Trucks Service Manual If the flow rate is above 8 gpm 30 L min replace the flow control and relief valve in the pu
22. ure in Table 1 5 1 and 5 2 oe ein the pump rele pressure does ro the exact relief pressure for the y match the relief pressure in Table 1 or Table 2 and the relief valve was power steering pump being diag previously replaced replace the nosed pump For instructions see If the pump relief pressure matches the relief pressure in Table 1 or 300 6 Heavy Duty Trucks Service Manual Supplement 32 January 2006 Power Steering Troubleshooting Procedures 46 17 Group 46 in the Heavy Duty Trucks Service Manual After replacing the pump evaluate the pump s perfor mance by repeating step 5 5 4 Test the pump relief valve reaction at idle e Run the engine at idle e Note the flow rate with the load valve open e Close the load valve until the pump relief pressure is reached The flow rate should drop to zero e Smoothly and quickly open the load valve and note the flow rate Repeat this action three times It should re turn to the flow rate noted above e Record on form SD 94 whether the relief valve operated correctly or not If the flow rate returns smoothly and quickly the relief valve is accept able Go to the next substep If the flow rate does not return smoothly and quickly the pump re lief valve is not working correctly Replace the relief valve if not done previously or replace the power steering pump 5 5 Test the pump relief valve reaction at 1500 rpm e Run the engine at 1500 rpm e No
23. uses and remedies for common noises associated with the power steering system and power steering pump 8 Check for leaks and restrictions and test the system back pressure 8 1 Check for leaks and restrictions 6 3 Adjust the poppet valves e Run the engine at idle e Turn the steering wheel to the full e Inspect all hoses and fittings for lock position signs of kinked or collapsed hoses or leaking fittings e Apply a 20 pound 89 newton force on the steering wheel while in the e Inspect all external seals full lock position e Repair all leaking fittings and re e Repeat the previous two instructions place parts as needed for the opposite turn e Replace any leaking seals If the poppets TRW gears only e Inspect the seal bores and sealing have been adjusted or reset prop surfaces for scrapes or burrs Make erly and after subsequent vehicle sure the seals are installed correctly operations loss of assist continues using the recommended tools as to occur when the wheel is too far instructed in the Heavy Duty Trucks from the axle stop the poppets have Service Manual become loose due to previous incor 300 10 Heavy Duty Trucks Service Manual Supplement 32 January 2006 Power Steering Troubleshooting Procedures 46 17 Troubleshooting Procedures Power Steering System Noise Possible Cause Remedy Growling or other abnormal steering noise Check the fluid level Check for air bubbles and foam Check for hose and
24. y 2006 Power Steering Troubleshooting Procedures 46 17 Troubleshooting Procedures 5 2 Check for erratic pump response while momentarily closing and opening the load valve o OK o Not OK 5 3 Pump relief pressure opsi okPa 5 4 Pump relief valve operated carectly at idle oOK o Not OK 5 5 Pump relief valve operated carectly at 1500 rpm o OK o Not OK 5 6 Partially close the load valve until the pressure gauge reads approximately 1800 psi 12 410 kPa or 2300 psi 15 858 kPa for high pressure steering gears Record flow rate with engine at idle and with the appropriate load applied ogpm oL min_ _ 5 7 Record flow rate with engine at 1500 rpm and no load applied ogpm aL min_ 5 8 Run engine at governed speed until fluid temperature stabilizes Record the maximum fluid temperature Do not exceed 250 F 121 C oF oC 5 9 Steering gear internal leakage Primary gear 1 0 gpm 3 8 L min max ogpm oL min Left Right optional Slave gear or ram 1 0 gpm 3 8 L min max Left Righ 6 Steering gear poppet adjustment 6 1 Check that pitman arm and sector shaft timing marks are aligned a Yes o No 6 2 Poppet relief pressure opsi akPa Left Right 7 Abnormal power steering noise 7 1 If not already done check for proper fluid level oFluid OK o Too low gToo high 7 2 Check fluid condition o Fluid OK oDiscolored o Foamy o Other 7 3 Hissing at less than fullturn o Yes o No 8 Check for leaks and restrictions and test the system bac
Download Pdf Manuals
Related Search
Related Contents
Gebrauchsanleitung こちらから ECU Software Calibration Instructions Installation Guide œ Bath Faucet and Hand Shower QC Test Peerless Industries SAL770 User's Manual Manual del propietario XPS-16 Drill Grinder And Sharpener User Manual 別紙 119 eTrex Legend Cx OM Trans-fr wo save track log.indd Copyright © All rights reserved.
Failed to retrieve file