BW12 auto box sump gasket leaking

[Yeldaw]

Hi I can't seem to stop the sump gasket leaking on my series 3. It has the Borg Warner 12 gearbox and so far I have tried swapping out the cork gasket for a modern compound one and changed the sump itself in case it was warped. But it still leaks, the bolts always seem to loosen slightly and I have re torqued then two or three times. Should I look to use instant gasket on each face of the sump gasket or are there any other tips to cure the problem.
Thanks
Dave

[D COUPE]

Any ideas?? This is my next job

DC

[PeterCrespin]

The sump is pressed steel and quite thin IIRC. With a squishy thick gasket the flange holes distort very easily if over-tightened. At which point people tighten them even more to try and stop the leak and it just gets worse.

Take the sump off and dress the flanges flat and start again with good sealant and don't over-tighten. Put a drop of Loctite on if you get the threads clean with petrol and a cotton bud. Don't use silicone in case any blobs migrate to the trans filter or valve block.

Pete

[D COUPE]

Thanks Peter will try that. Oil leaks I know are part of the jaguar package
but to cure one is a step in the right direction.

I have read somewhere about a different, not cork, gasket. Ever come
across one?

Thanks again

Dave C

[steve3.8]

After owning cars like the Stag , MGB etc , with distorted pressed steel rockers covers and sump pans that always leaked , this was my solution.

Thoroughly clean and degrease the sump or item . Find a flat surface , granite worktops are perfect when the wife?s not in , cling film an area big enough for the item , apply tiger seal to the sump . apply the gasket and hold lightly in place with strips of masking tape , place gently onto cling filmed surface ,put spare bolts in place to align the gasket , then press down in the centre , place a weight on top to keep an even pressure , [ bag of flour if you?re in the kitchen ] .
When cured peel off the cling film ,masking tape and clean out the holes with a modelling knife , the gasket face is now absolutely bang flat and only needs grease to make a seal to the engine / gearbox , it?s also easier to refit the item not having to concentrate on the gasket sliding about .

I use tiger seal because it stays glued to the gasket and stands up better against oil and petrol, unlike silicone which separates . If you ever need to remove the tiger seal I use a rotary wire wheel .
Steve

[hastylane]

Hi Dave,

Does the leak appear to be worse when the car is left to stand? The gearbox oil level rises when the engine is turned off as the torque converter drains back to the sump and the oil level will rise above the sump gasket. Two other places to look are the selector shaft seal and the kickdown connector. There is an o ring on the kickdown connector which goes hard with themp and may well be leaking. The selector shaft seal is more complicated to change and probable left to an expert. The kickdown connector is a plastic affair and literally allows a 12v feed into the gearbox.

Pete is correct to redress the warped sump, but do not use a sealant, a proper cork gasket will be fine. Do not overtighten the sump bolts.

Many years ago I used to build the auto gearboxes for Vicarage and we never used any sealant in my nine years of building all types of auto gearboxes.

P.s the kickdown connector is on the rhs of the gearbox and there are also the cooler pipes on the rhs, but if they were leaking you would know about it! Also donot be tempted with any autobox leak stoppers, they will ruin your gearbox because it swells all the seal and corrodes the aluminium parts inside.

Hope this helpful,

Kind regards Andrew

[Yeldaw]

Thanks, it is driving me mad. I have replaced the sump and used a different
gasket to the cork ones and it seemed to work for a week then it has started leaking again. I am wondering if the bolt threads are slightly worn because they
don't seem to be maintaining the same torque levels.

[goodoldgrandad]

Had the same apparent problem with mine, but found after 3 gasket changes (and then using an endoscope camera to probe around the out of sight places) that as mentioned earlier in this Post it was the Kickdown solenoid connector. It was dribbling down oil to rest around the sump flanges and it very much appeared that the sump gasket or bolts were leaking. Not easy to get to, but a very cheap fix for just an O ring. Several wasted sump gaskets later the oil leak is finally fixed - so don't assume oil on the sump bolts or around the pan flanges means the gasket has gone or the bolt threads causing a leak.

Info and photos about the fix on my Posting about the "Kickdown Solenoid Connector Access" viewtopic.php?t=8827

Also when filling or topping up the auto oil in the engine bay, make sure you use a long neck funnel to insert down the dip stick pipe beyond the "T" off for the small breather pipe - otherwise I found some oil runs down the breather pipe and can drip out underneath near to the kickdown connector - making you panic that the gasket has gone again !!! Don't be tempted to tighten up the sump bolts more than the torque setting, but check higher up the casing first. A good tip is to clean any excess oil off with a rag, then use pieces of tissue or kitchen paper to test dab around - it quickly shows up oil and quick means of tracing back to the source.