TRUCK SERVICE MANUAL
Crankcase Bearing Bores
Check fit of ball bearings in crankcase. Bearings
Wash curled hair from air strainer in cleaning
must be a finger press fit. If crank-case bearing bores
solution and then saturate it with clean oil, squeezing out
are worn or damaged, the crankcase should be replaced.
excess oil before replacing it in air strainer.
Cylinder Block Check for cracks or broken lugs on
cylinder block. Also check unloader bore bushings to be
sure they are not worn, rusted or damaged. If these
All ball bearings must be cleaned thoroughly in
bushings are to be replaced, they can be removed by
running a 1/8" pipe thread tap inside the bushing, then
inserting a 1/8" pipe threaded rod and pulling the bushing
INSPECTION OF PARTS
straight up and out. Do not use an easy-out for removing
Cylinder Head Body
Inspect cylinder head body for cracks or breaks.
Inlet Valve and Seats
Inspect condition of inlet valves and seats.
Replace if any defects are found.
If inlet valves are grooved deeper than .003" where they
contact the seat, they should be replaced. If the inlet
Test water jacket of cylinder head and cylinder
valve seats are worn or damaged so that they cannot be
block for leakage, using air pressure. Replace unit if
reclaimed by facing or lapping, seats should be replaced.
leakage is found. Discharge Valve Springs
Check cylinder bores for evidence of excessive
Discard all used discharge valve springs and
wear, out of round, or scoring. Cylinder bores which are
replace with new springs.
scored or out of round more than . 002", Fig. 6, or
Discharge Valves and Seats
tapered more than . 003", as should be re-bored or
Inspect condition of discharge valves and
honed oversize. Oversize pistons are available in .010",
discharge valve seats. If discharge valves are grooved
.020" or. 030" oversize. Cylinder bores must be smooth,
deeper than . 003" where they contact the seats, they
straight and round. Refer to specifications for proper
should be replaced. If the discharge valve seats are
clearance between piston and cylinder bore. Aluminum
worn excessively so there is no longer sufficient metal
left to reclaim the seat by using a lapping stone, the
seats should be replaced.
Crankcase and End Covers
Check crankcase and end covers for cracks and
broken lugs. Replace if any damage is found.
If an oil seal ring is used in the end cover, check fit
of ring in the ring groove and have .008" to .015"
clearance at the gap when placed in the end bore of the
crankshaft. Check oil seal ring for wear. If worn thin or
damaged, the oil seal ring must be replaced. Inspect oil
ring groove in end cover. If ring wear has formed a step
pattern in groove, replace end cover or machine groove
Fig. 6 Measuring Cylinder Bore Diameter