Oil leak from rear of crank

[wolseley6]

I have a 57 Minor with the original 948 engine. On a recent long trip it pumped all the engine oil into the gearbox bell housing in the space of 10 miles. I can only think it is coming out via the screw thread type seal on the end of the crank. The engine is now out and in bits. The only problem I can find is some slight damage to the oil slinger and the screw thread. The crankcase breather system seams to be in good order. Any thoughts please ?

[philthehill]

A photo of the damage to the oil thrower, crank screw and rear crank bearings would be appreciated. Better to make an informed judgement and give better advice.

[bmcecosse]

The oil is pushed out by crankcase pressure....so you need to look at the bores/pistons/rings for wear and tear. Also if the crank bearings are worn excessive oil floods the labyrinth and encourages even more oil to escape. I suggest a rebore with new oversize pistons - and a crank regrind with new oversize shells (and new oil pump) will be the best way forward. DO NOT be tempted to waste money on one of the useless 'rear seal' conversions......

[wolseley6]

Thanks for the replies, here is a picture of the crank[frame][/frame]

[philthehill]

Any chance of a picture of the rear main bearing cap with the main bearing fitted and visible. Is there any indication on the back of the bearing shell as to whether the crank has already been re-ground i.e. - 0.010. (ten thou re-grind)

[bmcecosse]

That rear main bearing is ripped to h3ll..... the engine definitely needs a crank regrind as a minimum....but DO pull the pistons for inspection.

[philthehill]

bmc
I agree with the condition of the crank but the crank may have already been re-ground to the limit so unless you know the existing crank size there may be no point in living in the hope that the crank can be re-ground. Better the know what size the crank is before expressing an opinion on the possibly of a re-grind; a good indicator of the existing crank size is the detail on the rear of the bearing shell currently fitted.

[bmcecosse]

It can't be reused as it is! So it will NEED to be reground - or exchanged for a good one. Unlikely to be reground to the limit already - but indeed the back of the old shell will tell all. As an aside - I don't see any problem with the crank tail - where it engages with the labyrinth.

[wolseley6]

The crank has previously been reground 10 thou, I should say the the damage to the main bearings was caused by the sudden oil loss. I think I will get an exchange crank from Bull Motif

[bmcecosse]

Check the bores/pistons/rings first..you may do better with an exchange engine complete. If you do go for the crank - get a new oil pump too.....

[wolseley6]

Thanks to everyone for their advice. Very helpfull