Onan MJA Series Service Manual page 92

90 ENG I NED I S ASS E M B LY
6. Replace the pushrods and fuel pump.
7. On MJC, install and retime the distributor, Sect 3.3.
3.9.5 CRANKSHAFT
These engines use a counter-balanced, ductile iron crankshaft. The 1
and 2 cylinder crankshafts ride on 2 lead-bronze bearings, the front
one housed in the crankcase and the rear one in the bearing plate. The
4-cylinder model MJC, uses an additional split center main bearing.
3.9.5.1 Removal.­
1. Remove the lock ring and retaining washer in front of the crankshaft
ge~r.
2. Pulloff the crankshaft gear.
It
has
I
2 1/4-20 UNC tapped holes for at ­
taching a gear pulling ring (ONAN
tool 420A248). Use care not to
damage teeth if the 'gear is to be
reused.
3. Remove the oil pan and the piston ­
and-connecting rod assemblies.
4. 4-CYLINDER ONLY. Remove the
bearing cap from the center main
bearing.
5.
Remove the rear bearing plate
from the crankcase. Note that
gaskets here adjust crankshaft endplay.
6. Remove the crankshaft through the rear opening in the crankcase.
(4-Cylinder Only; Catch the upper half of the main bearing support
as it slides off its mounting surface).
3.9. 5.2 Inspection. - Thoroughly clean the crankshaft and blowout all
oil passages with compressed air . Check all journals for out-of-round,
taper, grooving or ridges. Pay particular attention to ridges or grooves
FIG 3.9.H - REMOVING
CRANKSHAFT GEAR
on either side of the oil hole areas. Unusual conditions here often point
to previous neglect of oil cleanliness precautions.
If
the journal dimensions are not within the limits or the journals are
scored, re-machine the crankshaft.
3.9.5.3 Crankshaft Re-Machining. - Crankshaft machining requires a
trained and experienced operator and suitable equipment for handling
crankshafts with precision.