crank rear oil seal

[chilly]

how big a job is it to replace a leaking oil seal on the back end of the crank shaft? Is it an engine out job or can it be done in situ?

[Onne]

Engine out I'd say.

[bmcecosse]

There is no oil seal as such - it's a scroll. If oil is coming out there then it's usually caused by high internl pressure in the crankcase (or v high oil level!). Take the oil filler cap off when the engine is running - is there a plume of fume ?? If so - you need to correct that problem - usually a re-bore and new pistons and rings. It could of course just be the rear seal on the sump - easy enough to drop the sump and fit new gaskets and seals at each end - but these don't usually leak unles they have been incorrectly fitted or recently disturbed.

[Willie]

There is NO oil seal at the rear of the crankshaft. The minor uses an
'archimedes screw' arrangement whereby a thread cut into the crankshaft
revolves in the rear main bearing and 'screws the oil back into the sump!
This relies on very accurate tolerances and it is extremely common for oil
to leak out into the gearbox bellhousing and then to ground via the split pin
at the bottom. Even Gold Seal factory reconn'ed engines tend to leak.
The oil could be leaking from the rear sump cork sealing strip which is a
straightforward job.