Oil Leak - Sump or rear main?

[SimonBrown]

Currently have the engine out of my Series 2 OTS to investigate an oil leak amongst other things.
Ever since the engine was rebuilt 7 years/ 3000 miles ago it has leaked oil from the rear of the engine, only at higher engine speeds when hot.
On sump removal it was clear oil was leaking from the rear sump seal, it was very wet on both sides of the rubber seal.
There is no evidence of oil on the flywheel face or clutch, but significant amounts within the bell housing, mostly at the bottom.
However, the starter has plenty of oil within with a large amount of oily crud within the pinion housing.
The car has a lip seal conversion.
Any views on this as obviously I don’t wish to put it all back in thinking I have fixed it when I haven’t!
Thank you
Simon

[DWW]

From what you described it seems likely to be the sump seal leak, obviously one guy's opinion......

[Simonpfhc]

What you could do is put a new sump oil seal on and then put a load of cheap thin oil (SAE30) in. Then tilt the front of the engine up and leave it overnight. You should be able to see where any oil leaks out.

[SimonBrown]

Great idea!
Thank you Simon

[politeperson]

I assume you are sure it wasn't dripping down from the head?

The cam-shaft oil feed lines are often incorrectly fitted, adding to the oily mess at the back of the engine.

On the subject of the rear conversion lip seal, I dont bother any more as I have found it leaky and expensive. However if your crank has been altered you will have to go with it again I suppose.

I have however found the front crank seal conversion effective for oil leaks.

[flatfloor 3.8]

It's nearly always the sump rear seal that leaks and not the crank seal.When offering the sump back up it is easy to push the seal out of position. I always glue the rubber seal on with a couple of spots of super glue to hold it in position and use two coats of wellseal on all the matting surfaces and on the gaskets. Always use the rubber seal as opposed to the cork one which squelches out when tightened.

[44DHR]

My two penny worth - where did that saying come from ?
Similar concerns and now all sorted : -

viewtopic.php?f=3&t=19921&p=161846#p161846

I am convinced many superficial oil leaks come from the long sump paper type gasket surface area breaking down over time, plus the sump rear seal - especially a shrunken old style cork seal - to the main bearing housing rather than the main bearing rope seal. An easy and less effort fix to check and resolve compared to the rope seal replacement - if actually achieved effectively - or to the more radical and expensive crank machining.
Cheers,
Dave

[SimonBrown]

Took Simons advice and put a few litres of cheap oil in and tilted the engine.
Within a few seconds oil was dripping between the rear lip seal conversion and crank flange, so clearly from the rear main seal.
So, having very carefully installed the sump with new seals and gaskets, off with the sump again!
Not sure what to do now?
The rear lip seal conversion was done a few years ago in the States so I am not sure a replacement seal is available.
It is a split seal, so take a risk and clean/ reseal between the split and hope this works?
Or, bite the bullet, buy a second hand crank, re grind it as necessary and convert back to a rope seal?
Positively, pleased I took Simons advice and found it still leaking before putting the engine back in.
Getting all a bit expensive this🥲
Any advice much appreciated
Simon

[Simonpfhc]

Sorry to hear your news Simon, not a good outcome.

Take out the crank and carefully measure the newly machined area the lip seal rides against - diameter and width. I would then speak to a company that has a wealth of experience with these engines. There are a few out there, Rob Beere or Angus Moss come to mind.

They should be able to give you some decent options.

Good luck.

[andrewh]

If its a split seal then I think you have your answer. There is a fantastic post by Rory, RFS1957 which details the issue with cutting a lip seal in half to fit it. Pretty obvious when you read his article. There is no real fix unless you get the crankshaft out, when you have a number of choices. Sorry to hear this, but I think you will have to accept the flawed design of the lip seal and move on.

[mgcjag]

Hi Simon..have a read here and look into the GST raceing stretch seal...Steve viewtopic.php?f=4&t=16514&p=135842&hili ... al#p135842

[SimonBrown]

My crank has been ground to 2.632 inches, I believe to suit the Terrys Jaguar Parts conversion in the States, so options are a bit limited.
Light could clearly be seen between the seal and crankshaft, probably due to the seal not being trimmed properly during installation, and no rtv had been used at all, so the housing was just metal to metal.
I have ordered a new seal, will rtv the housing and ensure the seal is in full contact with the crank.
Hopefully this will fix it

[bitsobrits]

You might do others a service and post the name of the company who performed the rebuild/seal conversion.

When installing a new seal, it's good practice to provide a bit of lubrication to the sealing lip area of the seal to preclude a 'dry' start on first startup which can prematurely wear a seal. I use a very light smear of Graphogen, but most any grease will do. BTW-how is the machined finish of the sealing area on the crank? It should be very smooth, polished.

[SimonBrown]

Suffice to say the company in the States who did the conversion are no longer trading.
The surface of the crank where the lip seal should contact is fine thanks, smooth as the rear main bearing.

[Paul bow]

Try Gosnay engineering in Romford. They sell those seals, I have used them and currently have one in my car.. you have to make absolutely sure that the seal locates itself perfectly within the housing it comes with, that as well as having the split part at 2 o’clock. I’ve found that the seal symmetrical in the housing is the key to success with these. Rob Beere does a great conversion on the crank and a proper non split seal, albeit expensive and probably more work than you would like to undertake. Good luck