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BIG oil leak

Posted: Sun Aug 05, 2007 4:21 pm
by Matt
Im getting to my wits end with this car...

I have totally rebuilt the engine (1275 ital) with an overbore, new pistons and rings, new camshaft, mains and little ends reground, new bearings all round and its still peeing oil from between the sump and the backplate! it started after running for about 5 minutes.

The scroll looked to be okay, but it cant be that can it?? surely it would run into the bellhousing if that was the problem

Anyone got any ideas before (haha) I go insane?

Posted: Sun Aug 05, 2007 4:32 pm
by picky
have you fitted the cork or rubber gasket that is meant to seal the sump round the main bearing caps? sounds like the rear one is missing. also, what have you got setup for crankcase breathing? if there is too much pressure building up then you will have a high chance of oil leaks.

Picky

Posted: Sun Aug 05, 2007 4:40 pm
by Matt
Yes the cork gasket is there, it (a different one!) was before I rebuilt the engine... New gaskets everywhere. Breathing didnt make a difference before, but at the moment there is a vented cap in a rocker cover which is vented to the carb. There is a vent on the timing cover which is to atmosphere. Neither of the vents are blocked.

Posted: Sun Aug 05, 2007 6:10 pm
by bmcecosse
If it's coming down the backplate - then it is the rear sump pan seal. The cork (or better to use silicone rubber) seal must be left slightly long - so when the sump is bolted up it is compressed and seals completely. I know some will huff and puff - but I would also suggest a bead of silicone sealant on it - then bolt it up.

Posted: Sun Aug 05, 2007 7:48 pm
by Matt
BMC, I put sealant on it when I assembled it ;)

Leak is sorted, (dont critisise my choice of materials, it was all that was avaliable at 5pm on a Sunday, I will rectify it soon!) Attached the breather on the timing cover to the carb, and the rocker cover to the airbox. Also (as a v.temp bodge) put the oil filler cap in through a carrier bag to make it non vented, I will be looking for a non vented sort now though!

Posted: Sun Aug 05, 2007 9:02 pm
by bmcecosse
Just leave ot vented! The air flow will be negligible.

Posted: Sun Aug 05, 2007 9:04 pm
by Matt
ot?

Posted: Sun Aug 05, 2007 9:05 pm
by bmcecosse
it!

Posted: Sun Aug 05, 2007 9:15 pm
by Matt
hmm I will see how a vented cap works, but it will reduce the vacuum!

Posted: Sun Aug 05, 2007 9:20 pm
by bmcecosse
It will allow a nice cooling flow of air through the engine ! Actually - only one of your breathers should be connected to the inlet system - the other should admit the air. But if your engine is all nicely rebuilt - there should be no 'pressure' in the crankcase anyway!