TM 5-3810-300-24&P-3
1.2.2 EXAUST VALVES
2. Rotate the crankshaft to bring the valve and injector
rocker arms in line horizontally.
NOTE: When using a wrench on the
crankshaft bolt at the front of the engine, do
not turn the crankshaft in a left-hand direction
of rotation or the bolt will be loosened.
3. Disconnect and remove the fuel pipes from the
injectors and the fuel connectors.
CAUTION: Immediately after removing the fuel
pipes, cover each injector opening with a
shipping cap to prevent dirt or other foreign
Fig. 3 - Assembly of Exhaust Valves and Guides
matter from entering the injector.
When carbon deposits, due to partially burned fuel, build
4. Remove the two bolts holding the rocker arm shaft
up around the valve stems and extend to that portion of
brackets to the cylinder head.
Then, remove the
the stem which operates in the valve guide, sticking
brackets and shaft.
valves will result. Thus, the valves cannot seat properly
and pitted and burned valves and valve seats and loss of
5. Remove the exhaust valve bridge (four valve
compression will result.
cylinder head only), and bridge spring, if used.
Valve sticking may also result from valve stems which
6. Remove the cylinder block air box cover so piston
have been scored due to foreign matter in the lubricating
travel may be observed; then, turn the crankshaft until
oil, leakage of antifreeze (glycol) into the lubricating oil
the piston is at the top of its stroke.
which forms a soft sticky carbon and gums the valve
stems, and bent or worn valve guides. Sticking valves
7. Thread the valve spring compressor adaptor J
may eventually result in valves being held in the open
7455-7 into the rocker shaft bolt hole in the cylinder
position, being struck by the piston and becoming bent or
head. Apply pressure to the end of the valve spring
broken.
compressor handle J 7455-3
It is highly important that injector timing and valve
clearance be accurately adjusted and inspected
periodically. Improperly timed injectors will have adverse
effects upon combustion. Tightly adjusted valves will
cause rapid pitting of the valve seats and a hotter
running condition on the valve stems.
The cylinder head must first be removed before the
exhaust valves, valve seat inserts or valve guides can be
removed for replacement or reconditioning. However, the
valve springs may be removed without removing the
cylinder head, if necessary.
Remove Exhaust Valve Spring
It is possible, if occasion requires, to remove or replace
the exhaust valve springs without removing the cylinder
head. The springs, however, are normally removed
Fig. 4 - Removing Exhaust Valve Spring with Tool J 7455
when the head is off the engine.
To remove an exhaust valve spring without removing the
cylinder head from the engine, proceed as follows:
1. Remove the valve rocker cover.
Page 49
