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TM 5-4210-220-34
2-19.
ENGINE - Continued
2-19.7 Exhaust Valves - Continued
(9) Clean the inside of the valve guides with brush J5437 to remove all gum and carbon deposits from the
guides. Check the spiral grooves are clean.
(10) Inspect the valve guides for fractures, chipping, scoring, or excessive wear. Measure the valve guide inside
diameter with a pin gage or inside micrometer.
(11) Measure the outside diameter of the valve stems with a micrometer. If the clearance exceeds 0.005 in. (0.13
mm), replace valve guides as detailed in REPAIR following.
(12) Inspect the valve seat inserts for excessive wear, pitting, cracking or an improper seat angle. The proper
angle for the seating face of the valve is 30 deg., and the angle for the insert is 31 deg. If a valve seat has
been reground to such an extent that the grinding wheel contacts the cylinder head, install a new insert.
(13) Check the contact area between the valve and valve seat by applying a light coat of Prussian Blue or similar
paste onto the valve seat.
(14) Bounce the valve on the insert and check there is a line of contact around the whole seat. If not or the line is
wavy repair the seats as detailed in REPAIR following.
WARNING
Dry cleaning solvent P-D-680 (safety or Stoddard’s solvent) is potentially dangerous. Avoid repeated and
prolonged breathing of vapors and skin contact with the liquid. Do not use near open flame, arcing
equipment or other ignition sources. Always wear eye protection and protective clothing. The flash point of
P-D-680 is 100 to 138 deg. F (30 to 59 deg. C).
(15) Wash all components with dry cleaning solvent. Be sure all contaminants are removed.
INSTALLATION
(1) Check valve guides are totally clean. Lubricate the valve stems with gear oil (item 15, Appendix B) and slide
the valves into the guides. Be sure valves are installed in same location as noted in step 12 of REMOVAL
preceding.
(2) Hold the valves in place with a piece of masking tape (item 18, Appendix B) and turn cylinder head over.
Place a board beneath the valves to hold them in place.
(3) Install valve spring seats (9).
(4) If new oil seals (10) are being installed, place the plastic seal installation cap on the end of the valve stem. If
the cap extends more than 1/16 in. (1.6 mm) below the groove on the valve stem, remove cap and cut off
excess length.
(5) Lubricate the installation cap with gear oil (item 15, Appendix B) and start the seal carefully over the valve
stem. Push the seal down slowly until the seal rests on top of the valve guide. Remove the installation cap.
(6) Install the valve springs (8) over the guide and place spring caps (7) on top of spring.
2-208
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