PISTON - PISTON RINGS
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Check pistons to see if they are within wear limits.
Measure at thrust face and top of skirt.
The
thrust face is just below the oil control ring groove and is measured at right angles to the piston. pin
bore.
Pistons may be reused if within limits (See Clearance Section) and there are no scuff or score
marks. DO NOT reuse old rings-
always replace with new set.
Use the following procedure to replace
rings:
.
STEP 1 - Use ring expander and remove old rings.
Break old ring and use edge to clean up grooves-
be careful not to scrape edges of grooves.
STEP 2 - Place each new ring in its approximate running area in cylinder (push down to proper depth
.
with piston) then check end clearance.
.
STEP 3 - Install new rings on piston with ring expander.
Position slotted oil control ring first, dull or
black finish ring in middle groove and lighter or shiny ring in top groove.
Check side clear-
ance of rings in groove
--replace rings if necessary only in a set, not individually.
PISTON - ROD ASSEMBLIES
.
Normally, very little wear takes place in the piston boss-piston area.
If the original piston and
connecting rod can be reused after reconditioning,
the pin will usually not have to be replaced.
If the piston boss or connecting rod small end is worn beyond limits, use new piston-rod assembly
rather than rework the old piston boss and connecting rod.
A new piston pin should be used whenever a
new connecting rod is used with the original piston.
After checking pin,
rod and piston boss to make
sure proper clearances are available,
assemble piston to rod with pin (light interference to loose fit)
and lock pin with new retainers- make sure retainers are fully engaged in grooves.
CAMSHAFT - CAMSHAFT BUSHINGS
Inspect camshaft for evidence of excessive wear or damage.
Replace camshaft if cams, bearing
areas are grooved or worn beyond limits or if gear teeth (water pump drive) are chipped or damaged.
Also check keyway for cam gear
--replace camshaft if keyway is damaged.
Position new key on cam-
shaft and install cam gear--
replace if looseness is detected.
FIGURE 9-17 --
CHECKING RING END GAP
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FIGURE 9-12 --
RING INSTALLATION SEQUENCE
98
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