Rear main seal conversion disaster?

Hello all,

I am rather concerned that something went horribly wrong with the rear main seal (Terry’s Jag conversion with machined crankshaft per instructions?) on my fully rebuilt XK engine.

While fitting the engine + transmission back in the car (XJ6C), we had to lean the full lump quite steeply backwards as usual. Doing so, engine oil started dripping from the bell housing area, about a quart / litre came out.

Is there any scenario under which such a leak is normal? Could the leak come from anywhere else than the rear seal??

I am rather distraught at the prospect of taking everything apart again and checking the work done on the crankshaft… :frowning:

Thank you.

The leak can happen on a normal rope seal but not much more than a few drips. Sounds like something is wrong. Did you check the machined diameter of the crank vs the specs for the new seal? With Terrys conversion, you should have no leakage at all as until the seal dries out from age.

Well, I trusted the machine shop… they had all the right instructions and parts…

Well… right now, Id stop, pull the pan and flywheel off, and see if/how they messed it ip.

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I have been doing this kind of work for close to 50 years and have worked with some great machine shops. I always check the work to see if done right. Easier to check than do over.


First thing I would verify is that the seal lips were pointed in, not out.


Also, ensure the pan rail seal was installed correctly, and of the correct dimension.

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The engine is mated to a THM700 with the John’s Cars adapter kit. I wonder if may be I simply missed a bolt that goes all the way to the oil passages and the oil is pouring through the vacant thread hole…

The oil gallery plug? Unlikely but who knows! Good luck!

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Iksmay on the allery ugpay, to @Erica_Moss:face_with_raised_eyebrow:

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Unless the seal was literally forgotten…it has to be that plug. At least it wasn’t installed, connected, and turned over.

I think it is recommended that the new seal carrier be siliconed to the block, and that may have been forgot, but a quart from that is unlikely?

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I hope indeed it is the the plug at the end of the oil galley…

Quart might be about right for the volume behind the plug and it would come out quickly. But if the engine sat level before I think that would have drained long, long ago.

Maybe pulling the starter will do as an entry point for a mirror/ camera? Does your transmission allow for a look? I hope it’s not the machining. Too bad…

Paul you ok?

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I was just wondering :grimacing:

In my case it did not happen until the starter was cranked. But my engine was kept level. I don’t really know if extreme tipping could get oil into that long drilling or not.

It’s empty and above oil level until the channels are primed - pump at the front - would that much get out via the rear bearings?
I think it’s plausible, we’ll find out. Very sorry it has to come out at such a late stage.

I had started the engine for a few seconds on the bench before fitting it into the car. Am I right to think that this oil galley is not under pressure, just atmospheric, yeah?

No it has full oil pressure in a running engine. Without the plug in it would probably empty out in seconds. If you have a USB wand camera you can go up behind the flywheel and look at it with that 4 bolt steal cover removed.

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If it was leaking from the rear galley bolt, it would have dumped a lot more during running than just being tilted.