Chrysler Full-Size Trucks 1989-1996 Repair Guide

Valves

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REMOVAL & INSTALLATION



See Figure 1

  1. Remove the cylinder head from the vehicle.
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  3. Block the head on its side, or install a pair of head-holding brackets made especially for valve removal.
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  5. Use a socket slightly larger than the valve stem and keepers, place the socket over the valve stem and gently hit the socket with a soft faced hammer to break loose any varnish buildup.
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  7. Remove the valve keepers, retainer, spring shield and valve spring using a valve spring compressor.
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  9. Remove the valves from the cylinder head and place them, in order, through numbered holes punched in a stiff piece of cardboard or wood valve holding stick.
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Fig. Fig. 1: Invert the cylinder head and withdraw the valve from the cylinder head bore

The exhaust valve stems, on some engines, may be equipped with small metal caps. Take care not to lose the caps. Make sure to reinstall them at assembly time. Replace any caps that are worn.

  1. Put the parts in a container numbered for the cylinder being worked on; do not mix them with other parts removed.
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To install:
  1. Install the valves in the cylinder head and metal caps, if applicable.
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  3. Install new valve stem oil seals.
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  5. Install the valve keepers, retainer, spring shield and valve spring using a valve spring compressor.
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  7. Check the valve spring installed height, and shim or replace as necessary.
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CLEANING AND INSPECTION



See Figures 2, 3 and 4

There is some overlap of the steps in this procedure with the steps in the cylinder head cleaning and inspection procedure. If you have followed that procedure already, disregard the redundant steps here as you deem acceptable.

  1. Remove and discard the valve stem oil seals. A new seal will be used at assembly time.
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  3. Use an electric drill and rotary wire brush to clean the intake and exhaust valve ports, combustion chamber and valve seats. In some cases, the carbon will need to be chipped away. Use a blunt pointed drift for carbon chipping. Be careful around the valve seat areas.
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Fig. Fig. 2: Valve stems may be rolled on a flat surface to check for bends



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Fig. Fig. 3: Use a micrometer to check the valve stem diameter

  1. Use a wire valve guide cleaning brush and safe solvent to clean the valve guides.
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  3. Clean the valves with a revolving wire brush. Heavy carbon deposits may be removed with a blunt drift.
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When using a wire brush to clean carbon on the valve ports, valves etc., be sure that the deposits are actually removed, rather than burnished.

  1. Wash and clean all valve springs, keepers, retaining caps etc., in safe solvent.
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  3. Clean the head with a brush and some safe solvent, then wipe dry.
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  5. Check the head for cracks. Cracks in the cylinder head usually start around an exhaust valve seat because it is the hottest part of the combustion chamber. If a crack is suspected but cannot be detected visually have the area checked with dye penetrant or other method by a machine shop.
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Fig. Fig. 4: Use a dial gauge for greatest precision when measuring the valve guide wear

  1. After all cylinder head parts are reasonably clean, check the valve stem-to-guide clearance. If a dial indicator is not on hand, a visual inspection can give you a fairly good idea if the guide, valve stem or both are worn. Use a dial indicator to be sure.
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  3. Insert the valve into the guide, slightly away from the valve seat. Wiggle the valve sideways. A small amount of wobble is normal, excessive wobble means a worn guide or valve stem. If a dial indicator is on hand, mount the indicator so that the stem of the valve is at 90° to the valve stem, as close to the valve guide as possible. Move the valve off the seat, and measure the valve guide-to-stem clearance by rocking the stem back and forth to actuate the dial indicator. Measure the valve stem using a micrometer and compare to specifications to determine whether stem or guide wear is causing excessive clearance.
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REFACING



See Figures 5, 6, 7, 8 and 9

  1. The valve guide, if worn, must be repaired before the valve seats can be resurfaced. Chrysler supplies valves with oversize stems to fit valve guides that are reamed to oversize for repair. A machine shop will be able to handle the guide reaming for you. In some cases, if the guide is not too badly worn, knurling may be all that is required.
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Fig. Fig. 5: Valve tip to valve spring seat dimensions-2.5L engine



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Fig. Fig. 6: The valve seats should be ground along the critical dimensions in the drawing-diesel engine shown



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Fig. Fig. 7: The valve depth is measured along the dimensions indicated-diesel engine valve shown

  1. The valve seats should be a true 45° angle. Remove only enough metal to clean up the valve face or to correct run-out. If the edge of a valve head, after machining, is 1 / 32 in. (0.8mm) or less, replace the valve. The tip of the valve stem should also be dressed on the valve grinding machine, however, do not remove more than 0.010 in. (0.254mm). If necessary, have a machine shop resurface the valves and seats. Remove only enough material to clean up any pits or grooves. Be sure the valve seat is not too wide or narrow.
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Fig. Fig. 8: Refacing the valve seats

  1. After the valves are refaced by machine, they may have to be hand lapped. Check with your machine shop whether this operation is necessary. In many cases, it is not necessary due to the greater degree of precision in today's machining operations, and also for the fact that some hardened valve seat materials cannot be hand lapped. If the machine shop recommends it, hand lap them with grinding compound. Clean the grinding compound off and check the position of face-to-seat contact. Contact should be close to the center of the valve face. If contact is close to the top edge of the valve, narrow the seat; if too close to the bottom edge, raise the seat.
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Fig. Fig. 9: The valve seat width is measured with a special scale like the one shown

  1. After all valve and valve seats have been machined, check the remaining valve train parts (springs, retainers, keepers, etc.) for wear. Check the valve springs for straitness and tension.
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