Big Block Rear Oil Seal Issues

Philth · Post by **Philth** » Sat May 02, 09 7:10 pm

Turnip's having trouble with the rear oil seal on his Barracuda race car - basically it was leaking in a constant stream when the team was loading it up to go race at Shakey this weekend.

Three hours later and a new seal was fitted, but it still leaked just as bad. Apparently the one that was on there was the wrong way round according to the 'diagram' that came with the new seal, although it was fine from engine built through to the end of the Pod at Easter (engine run-in, burn-outs for the boys, start-up after winter lay-up, a few runs up the track at the Pod, not a drop was leaked!), and I'm damn sure it was the correct way round when installed (lip facing in towards the crank?)

He's car is now in the workshop and it was noticed that the dowels are missing fromn the block to locate the transmission. This can potentially have an affect on the seals ...

Why do these things suddenly go, especially not under any 'pressure' - hell, better when loading than halfway down the track I suppose!

Crank seal fitment - diffinitive answer & tips and techniques for John, please!

Cheers!

Anonymous · Post by **Anonymous** » Sun May 03, 09 8:55 pm

The lip faces towards the front of block , has the crank got 'knurl' marks on the journal where the seal runs? , sometimes these have to be cleaned up.

Definately the seal?.

Dave999 · Post by **Dave999** » Tue May 05, 09 12:12 pm

rope seal???

steep it in oil for 2 weeks (so it doesn't burn on start up)

fit it trim it

never look at it again

Dave

Philth · Post by **Philth** » Fri May 08, 09 8:51 pm

Lip facing into the block was definitely the way it was fitted. That's how mine is fitted and it's as dry as a bone on the outside.

I did a bit of research and came away with two main factors: -

1) oil level too high (the leak was noticed when loading the car, I think).

2) crank case pressure 'pushing' oil out of the seal - John has the pressure evacuated from the cam covers to the exhausts.

Adam - the crank is new so the knurls are fine, but good call anyway.

But why do these things suddenly give up? Hmm, could there be another cause, as Adam suggests???

I've never liked the stupid way the rear oil seal is designed on a BB anyway. A two piece seal? Dumb fibre strips down the side of the sealing block? Even the MG owners club would scoff at that.

I would have thought that a new design would have been thought up by now, what with all the other 'innovations' on the market for SB's and BB's...

Rah.

Blue · Post by **Blue** » Fri May 08, 09 8:55 pm

Yes Phil, there is a new fangled billet seal retainer out there that uses a rubber seal down the sides.

That leaks as well.

Dave-R · Post by **Dave-R** » Fri May 08, 09 8:58 pm

Maybe the exhaust is pressurising the crankcase instead of evacuating it?

Anonymous · Post by **Anonymous** » Fri May 08, 09 9:09 pm

Some cranks will have a 'cross hatch' pattern where the seal fits , this is what i meant , not talking damage marks.

You can stagger the two halves so the joint is @ 11 & 5 o'clock as opposed to 9 & 3 o'clock , sometimes the seal has to be trimmed down a tad otherwise the two sufaces will meet @ the ends & not seal round the journal , silicone is all you need down the sides.

Was the seal lubed before fitting the crank?

Has the block been line bored/honed?

Leaking from rear gallery plugs/cam core plug?

Valley plate/valve covers?

Sender plug.

Oil sender.

Philth · Post by **Philth** » Thu May 28, 09 7:24 pm

UPDATE

Turns out it was a flexplate bolt rubbing the back of the engine and the camshaft bore core plug just enough to nick it and cause the oil leak

. Come to think of it the way John originally described to me did sound like a pressurised oil leak rather than a non-pressurised leak.

All fixed now. Hopefully.

The crank oil seals are still a Bananarama! design.