REMOVAL & INSTALLATION
- Remove the cylinder head(s) and place on a clean surface.
- Block the head on its side, or install a pair of head-holding brackets made especially for valve removal.
- 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 plastic hammer to break loose any varnish buildup.
- Remove the valve keepers, retainer, spring shield and valve spring using a valve spring compressor (the locking C-clamp type is the easiest kind to use).
- Put the parts in a separate container numbered for the cylinder being worked on. Do not mix them with other parts removed.
- Remove and discard the valve stem oil seal, a new seal will be used at assembly time.
- Remove the valve from the cylinder head and place, in order, through numbered holes punched in a stiff piece of cardboard or wooden valve holding stick.
The exhaust valve stems, on some engines, are 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.
- 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.
- Use a wire valve guide cleaning brush and safe solvent to clean the valve guides.
- Clean the valves with a revolving wire brush. Heavy carbon deposits may be removed with the blunt drift.
When using a wire brush to clean carbon from the valve ports, valves, etc., be sure that the deposits are actually removed, rather than burnished.
- Wash and clean all valve spring, keepers, retaining caps etc., in safe solvent.
- Clean the head with a brush and some safe solvent and wipe dry.
- 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.
- 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.
- Insert the valve into the guide until 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.
- The valve guide, if worn, must be repaired before the valve seats can be resurfaced. Ford supplies valves with oversize stems to fit valve guides that are reamed to oversize for repair. The 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.
- Reface, or have the valves and valve seats refaced. The valve seats should be a true 45° angle for the 2.5L and 3.0L engines, and 44.5° angle for the 3.8L engine. Remove only enough material to clean up any pits or grooves. Be sure the valve seat is not too wide or narrow. Use a 60° grinding wheel to remove material from the bottom of the seat for raising and a 30° grinding wheel to remove material from the top of the seat to narrow.
- After the valves are refaced by machine, hand lap them to the valve seat. 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.
- Valves should be refaced to a true angle of 44° for the 2.5L and 3.0L engines, and 45.8° for the 3.8L engine. Remove only enough metal to clean up the valve face or to correct run-out. If the edge of the valve head, after machining, is 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. (0.25mm).
- 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 straightness and tension.
- Reassemble the head in the reverse order of disassembly using new valve guide seals and lubricating the valve stems. Check the valve spring installed height, shim or replace as necessary.