Chrysler Caravan/Voyager/Town n Country 1984-1995

Valve Lash

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Valve lash adjustment determines how far the valves enter the cylinder, and how long they stay open and closed.

If the valve clearance is too large, part of the lift of the camshaft will be used in removing the excess clearance. Consequently, the valve will not be opening as far as it should. This condition has two effects: the valve train components will emit a tapping sound as they take up the excessive clearance and the engine will perform poorly because the valves does not open fully and allow the proper amount of gases to flow in and out of the engine.

If the valve clearance is too small, the intake valve and the exhaust valves will open too far and they will not fully seat on the cylinder head when they close. As a result, the valves will also become overheated and will warp, since they cannot transfer heat unless they are touching the valve seat in the cylinder head.

While all valve adjustments must be made as accurately as possible, it is better to have the valve adjustment slightly loose then slightly tight as a burned valve may result from overly tight adjustments.

ADJUSTMENT



Valve adjustment must be performed after any engine overhaul or when the valve train components emit a tapping sound requiring valve adjustment service.


CAUTION
Always apply the parking brake and block the wheels before performing any engine running tests.

2.2L, 2.5L, 3.0L, 3.3L and 3.8L Engines

The 2.2L, 2.5L, 3.0L, 3.3 and 3.8L engines use hydraulic lash adjusters. No periodic adjustment or checking is necessary.

2.6L Engines
WITH JET VALVES

See Figure 1



Click image to see an enlarged view

Fig. Fig. 1: Adjusting the valve lash-2.6L engines

A jet valve is added on some models. The jet valve adjuster is located on the intake valve rocker arm and must be adjusted before the intake valve.

  1. Start the engine and allow it to reach normal operating temperature.
  2.  
  3. Stop the engine and remove the air cleaner and its hoses. Remove any other cables, hoses, wires, etc., which are attached to the valve cover, remove the valve cover.
  4.  
  5. Disconnect the high tension coil-to-distributor wire at the distributor, and allow it to contact a known good engine ground.
  6.  
  7. Tighten the cylinder head bolts in the correct sequence and to the specified torque value. For more details, refer to Engine & Engine Overhaul .
  8.  
  9. Have a helper bump the ignition switch. Watch the rocker arms until piston No. 4 cylinder is at Top Dead Center (TDC) and adjust jet valves as follows:
    1. Back out the intake valve adjusting screw two or three turns.
    2.  
    3. Loosen the locknut on the jet valve and back out the jet valve adjusting screw.
    4.  
    5. Install a 0.005 in. (0.15mm) feeler gauge between the jet valve stem and the jet valve adjusting screw.
    6.  
    7. Turn in the jet valve adjusting screw until it slightly makes contact with the jet valve stem. While holding the jet valve adjusting screw in place, tighten the jet valve locknut. Recheck the clearance.
    8.  

  10.  
  11. Complete the adjustment by adjusting intake and exhaust valve clearance on the same cylinder as the jet valve you've finished. Refer to Valve Clearance Specification Chart.
  12.  

WITHOUT JET VALVES
  1. Start the engine and allow it to reach normal operating temperature.
  2.  
  3. Stop the engine and remove the air cleaner and its hoses. Remove any other cables, hoses, wires, etc., which are attached to the valve cover, remove the valve cover.
  4.  
  5. Disconnect the high tension coil-to-distributor wire at the distributor, and allow it to contact a known good engine ground.
  6.  
  7. Tighten the cylinder head bolts in the correct sequence and to the specified torque value. For more details, refer to Engine & Engine Overhaul .
  8.  
  9. Have a helper bump the ignition switch. Watch the rocker arms until the piston is at Top Dead Center (TDC) of the compression stroke (both valves closed).
  10.  
  11. Loosen the valve adjuster locknut. Back out the valve adjusting screw and install a feeler gauge between the adjusting screw and valve stem.
  12.  
  13. Turn in the valve adjusting screw until it slightly touches the feeler gauge. While holding the adjusting screw in place, tighten the adjusting screw locknut. Refer to the Valve Clearance Specification Chart.
  14.  
  15. Perform Steps 5-7 on the remaining three cylinders.
  16.  

 
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