Chrysler Full-Size Trucks 1989-1996 Repair Guide

Valve Lash

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ADJUSTMENT



Gasoline Engines

No valve lash adjustment is necessary or possible on any of the Plymouth/Dodge-built engines covered by this information. Hydraulic valve lifters automatically maintain zero clearance. After engine reassembly, these lifters adjust themselves as soon as engine oil pressure builds up.

Diesel Engine

See Figures 1, 2 and 3

Valve adjustment is required on the diesel engine every 36,000 miles (57,971 km).

The timing pin is used in this procedure to locate Top Dead Center (TDC). It is found at the back of the gear housing and below the injection pump. Be sure to disengage the timing pin after locating TDC.

WARNING

Do not set the valve lash closer than specified in an attempt to quiet the lifters. This will only result in burned valves.

  1. The engine must be cold for this adjustment (below 140°F/60°C).
  2.  
  3. Remove the valve cover.
  4.  



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Fig. Fig. 1: Use the timing pin to locate TDC for diesel engines

  1. Manually turn the engine and use the timing pin to locate Top Dead Center (TDC) for cylinder No. 1. Disengage the timing pin after locating TDC.
  2.  
  3. Perform the following two-step procedure to adjust the valves. Refer to the accompanying illustrations to determine which valves to adjust in each of the steps:
    1. Valve lash is measured between the rocker arm and the end of the valve. Check the lash by inserting a feeler gauge between the rocker arm and the valve. Adjust the clearance, if necessary. The clearance for the intake valves is 0.010 in. (0.254mm). The clearance for the exhaust valves is 0.20 in. (0.508mm). Adjust the lash by loosening the locknut on the rocker arm and turning the adjusting screw. After the adjustment is made, tighten the locknut to 18 ft. lbs. (24 Nm) and recheck the lash to be sure it did not change as the locknut was being tightened.
    2.  
    3. Double-check that the timing pin is disengaged, then mark the pulley and turn the engine crankshaft 360° in the normal direction of rotation (clockwise). Check and adjust the clearance of the indicated valves following the same specifications as in Step 4a.
    4.  

  4.  



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Fig. Fig. 2: Adjust the intake and exhaust valves shown in this first phase of the diesel valve adjustment procedure



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Fig. Fig. 3: Adjust the intake and exhaust valves shown in this second stage of the diesel valve adjustment

  1. Install the rocker cover with a new gasket, then attach the fuel line to the injector. Start the engine and check for leaks.
  2.  

 
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