Perkins L4 Workshop Manual - L-36 Fleet

Page L2 Crankshaft and Main Bearings-continued
Should the Crankshaft rear flange need regrinding,
the rear i in. (9.52 mm) of the flanse
width must not be ground. The remaining portion
of the flan ge width may be ground to a minimum
diameter of 5.238 in. (133.05 mm). Surface finish
not to exceed 16 micro ins. (.4 microns).
To Fit Ne" Main Bearings and Thrust Washers.
The main bearings being of the pre-finished
strip type, the fitting of these should present nu
difficulty .
To prevent errors occurring in fitting top and
bottom half bearings, the locating lips, and the
recesses in the caps and bearing housings, are
offset in relation to one another.
The bearing caps and crankcase are numbered
1-3. No. I being at the front of the engine.
To avoid the caps being inadvertently assem bied
to the crankcase the wrong war round the locating
dowels and dowel holes are also offset.
Under normat circumstances by the time the
main hearings require to be renewed, the crankshaft
will Deed to be removed for regrinding. However,
if for any reason one or more of the bearing~
should have to be renewed or removed for inspection,
this caD be carried out on Nos. land 2
bearings without the necessity of removing the
crankshaft from the engine.
Proceed as follows :-
Remove sump (See Section P).
Take olf tbe cap of the hearing in question.
Slacken remaining bearing cap setscrews one
or two turns.
Remove the lower half of the bearing from the
bearing cap.
With a suitable piece of wood push out the top
half of the hearing by rotating it on the crankshaft,
applying the tooi to the side opposite the locating
lip. The locating lips are on the camshaft side
of the engine.
Inspect the bearing shells and if thor require
renewing insert.a new half hearing in the top,
insertiIÏg plain end first. Fit new half hearing to
cap. Do not remove more than one bearing at
a time.
Replace cap and tighten setscrews Ijghtly b~fore
proceeding to next bearing.
Having replaced the bearings and caps pull
down the setscrews with a torque wrench set to
the tension given in S~ction B.
The thrust washers fit in the recesses provided
on either side of the rear main bearing housing and
should be assembied with the flat steel side to the
hearing housing. The end float of the crankshaft is
measured between the crank cheek and the thrust
washers. This measurement should be between
.0085 and .0155 in. (.22 and .39 mm). If greater
or smaller than this amount fit new thrust was hers
or oversize thrust washers if necessary.
Crankshaft Rear End Seal.
On early engines, this seal consisted of a housing
and rubber seal.
When removed it should be inspected for cracks
or scratches on the bearing surface. If this surface
is damaged in any way a new seal should be fitted.
To fit a new seal proceed as follows :-
Remove old seal by pressing it out of the housing.
Lightly smear the outer edge of the new seal
with soft soap.
Place seal in position and press in by hand as
far as it will go, this should be approximately halfway
in. Pressing in halfway by hand ensures
that the seal is centralised.
Press in with a press until the bevelled edge or
the seal is level with the outer face of thc: housing.
MODIFIED CRANKSHAFf AND REAR ou..
SEAL
Later L4 engines incorporate a crankshaft and
rear oil seal of modified design. Neither of these
components are individually interchangeable with
their earlier counterparts so that if the latest type
crankshaft is [0 be fitted to an engine previously
utilising an unmodified crankshaft, a modified rear
oil seal must also be fitted.
The modification to the crankshaft affects that
part of the shaft around which the rear oil sea!
is fitted. Whereas, previously, th is portion of the
shaft had a nomina! diameter of 5* in. (133.4 mm).
the equivalent nomina I dimension in the case of
the modified shaft is 3i in. (79.38 mm). Further.
more the modified crankshaft has a shallow spi ral
oil groove machined to a depth of .004(.008 in.
(.10 to .20 mm) in that section upon which the
rear scat bears.
With the advent of this latest type crankshaft,
the bore of the modified rear Dil seal is machined
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