REMOVAL & INSTALLATION
See Figures 1 through 7
- Remove the cylinder head and rocker arm shafts (gasoline engines only) as detailed previously in this section. For the diesel engine, remove the camshaft as detailed later in this section. Lift out the valve lifters and any accompanying shims.
Always be sure to keep all valve train components in the proper order to assure installation in their original locations
- Using a suitable valve spring compressor tool, compress the spring and remove the keepers.
- Lift off the spring retainer and the spring.
- Pull off the valve oil seal and the lower spring seat. Remove the valve through the bottom of the cylinder head.
When removing the valve seal and the lower spring seat, a small screwdriver and a magnet may come in handy
- Inspect the valve and spring. Clean the valve guide with a cotton swab and solvent. Inspect the valve guide and seat, then check the valve guide-to-stem clearance.
- Lubricate the valve stem and guide with engine oil. Install the valve in the cylinder head through the bottom and position the lower spring seat.
- Lubricate the valve seal with engine oil and then install it into position over the lower spring seat.
When installing seals, ensure that a small amount of oil is able to pass the seal to lubricate the valve guides; otherwise, excessive wear may result
- Install the valve spring and the upper spring retainer, then compress the spring using the compressor tool and install the valve keeper(s).
Tap the installed valve stem lightly with a rubber mallet to ensure proper fit
- Don't forget the valve lifters and shims on the diesel engine. Make sure the lifters rotate smoothly in the cylinder head.
See Figures 5 through 11
Inspect the valve faces and the cylinder head valve seats for pits, burned spots and other evidence of poor seating. If the valve face is in such bad shape that the head of the valve must be ground in order to true up the face, discard the valve because the sharp edge will run too hot. The correct angle for valve faces is given in the specification charts found earlier in this section. It is recommended that any reaming or resurfacing (grinding) be performed by a reputable machine shop.
Check the valve stem for scoring and/or burned spots. If not noticeably scored or damaged, clean the valve stem with a suitable solvent to remove all gum and varnish. Clean the valve guides using a suitable solvent and an expanding wire-type valve guide cleaner (generally available at a local automotive supply store). If you have access to a dial indicator for measuring valve stem-to-guide clearance, mount it so that the stem of the indicator is at a 90° angle to the valve stem and as close to the valve guide as possible. Move the valve off its seat slightly and measure the valve guide-to-stem clearance by rocking the valve back and forth so that the stem actuates the dial indicator. Measure the valve stem using a micrometer, and compare to specifications in order to determine whether the stem or the guide is responsible for the excess clearance. If a dial indicator and a micrometer are not available, take the cylinder head and valves to a reputable machine shop.
Use a steel square to check the squareness of the valve spring. If the spring is out of square more than the maximum allowable (K-series: 0.063 in. or 1.6mm. A-series engines: 0.079 in. or 2mm. T-series engines: 0.075 in. or 1.9mm.), it will require replacement. Check that the spring height and strength is up to specifications. If the spring is weak, it must be replaced. If the installed height is incorrect, add shim washers between the spring pad and the spring.
Use only washers designed for this purpose
See Figure 12
Valve refacing should only be handled by a reputable machine shop, as the experience and equipment needed to do the job are beyond that of the average owner/mechanic. During the course of a normal valve job, refacing is necessary in cases when simply lapping the valves into their seats will not correct the seat and face wear. When the valves are reground (resurfaced), the valve seats must also be recut, again requiring special equipment and experience.
See Figure 13
The valves must be lapped into their seats after resurfacing, to ensure proper sealing. Even if the valves have not been refaced, they should be lapped into the head before reassembly.
Set the cylinder head on the workbench, combustion chamber side up. Rest the head on wooden blocks on either end, so there are 2-3 in. (51-76mm) between the tops of the valve guides and the bench.
- Lightly lube the valve stem with clean engine oil. Coat the valve seat completely with valve grinding compound. Use just enough compound that the full width and circumference of the seat are covered.
- Install the valve in its proper location in the head. Attach the suction cup end of a valve lapping tool to the valve head. It usually helps to put a small amount of saliva into the suction cup to aid it sticking to the valve.
- Rotate the tool between your palms, changing position and lifting the tool often to prevent grooving. Lap the valve in until a smooth, evenly polished seat and valve face are evident.
- Remove the valve from the head. Wipe away all traces of grinding compound from the valve face and seat. Wipe out the port with a solvent soaked rag, then swab out the valve guide with a piece of solvent soaked rag to make sure there are no traces of compound grit inside the guide. This cleaning is important.
- Proceed through the remaining valves, one at a time. Make sure the valve faces, seats, cylinder ports and valve guides are clean before reassembling the valve train.