CRANKSHAFT AND MAIN BEARINGS—H.3
To Remove the Crankshaft
To carry out this operation, it will be necessary to
remove the engine from the application and mount it in a
suitable dismantling stand.
If the original components are to be refitted they
should be suitably marked for re-assembly to their
original positions.
1.
Remove the sump, sump strainer and the oil pump
suction and delivery pipes.
2.
Remove the timing gears and timing case. (See
Page K.3).
3.
Remove the starter motor, flywheel and flywheel
housing.
4.
Remove the connecting rod caps and big end
bearings (See Page F. 1).
5.
Remove the rear main oil seal housing.
6.
Take off the rear main bearing bridge piece.
7.
Remove the oil pump from the front main bearing
cap (See Page L.3).
8.
Remove main bearing cap setscrews.
9.
Remove the main bearing caps and half bearings.
10.
Lift out the crankshaft and remove the other half
bearings.
Fig. H.4.
Exploded view of Crankshaft and Main Bearings.
Regrinding the Crankshaft
(see Data, Page H.8)
Before regrinding the crankshaft, the following points
should be checked to ensure it is suitable for further
machining.
(a)
The crankshaft should be crack-detected before
regrinding. It must, of course, be remembered to
demagnetize the crankshaft after crack detecting, in
order to remove any polarization which may be
present.
(b)
The main journal and crankpin diameters should be
checked to ascertain the next appropriate size to
which the crankshaft can be reground, i.e., —0.010
in (—0.25 mm), —0.020 in (—0,51 mm) or —0.030
in ( —0.76 mm). If the crankshaft requires to be
reground below -0.030 in (-0,76 mm) it is
recommended that a new crankshaft be fitted. See
"Technical Data" for crankshaft regrind dimensions.
(c)
The dimensions given in "Technical Data' for the
crankpin width apply only to a standard crankshaft.
It will be appreciated that this dimension may
increase as the crankpins are reground. but after
regrinding the maximum width should not exceed
1,635 in (41,53 mm). During regrinding, all the
limits must be adhered to, and the main journals
and crankpins must be free from grinding marks.
After regrinding, the sharp corners on the oil holes
should be removed and the crankshaft crack detected
again and demagnetized.
Note:
It is important that the radii on the
main journals and crankpins are
maintained. If these are neglected, a
fracture is liable to occur.
To Refit the Crankshaft
1.
Ensure all oilways are free from obstruction.
2.
Check the main bearing setscrews for stretch or
damage to the threads. In no case should
setscrews other than those supplied by the engine
manufacturer be used as they are of a special heat
treated high grade steel.
