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MG MGA - Leaking front gearbox cover

Hi all,

Some of the longer standing members amongst us may remember a thread I started about 2 years ago regarding an excessive quantity of oil which (almost suddenly) started dripping out of the drain hole in my 1600's gearbox bellhousing. This was on a fresh engine/gearbox rebuild with just under 1,200 miles on the clock. I was initially drawn to the problem by smoke emanating from around the starter motor bendix - suggesting that oil was been thrown onto the clutch.
The oil was definitely gear oil with the leak most evident immediately after switching off the engine.

Well the other week I finally bit the bullet and pulled the engine (leaving the gearbox in place). As you can see from the pics which follow, there was definitely oil inside the bellhousing - if far less than I was expecting (maybe because the car was standing for quite a while after last being run).

But what has me stumpted is from where the oil was actually leaking. The first motion shaft was dry, as was the clutch. The oil seal in the front cover still looked like new, and by my eyes the gasket was sealing hard up against the cover. My only observation is that perhaps it was coming out from around the stud near the layshaft?

Does anyone have any ideas looking at the pics? Otherwise I'm thinking of just putting it all back together with new seals / shims etc and crossing my fingers.

NB. I have measured the bearing to cover end float using plastigauge to be approx 0.007 in - two 0.002 in shims were in place in the car.

Cheers

Steven


S HILL

Attached is a pic with the front cover removed


S HILL

And a close-up
S HILL

sorry, here is the close up


S HILL

hmmmm. I don't see the oil. Unfortunate the engine has been pulled because you could put ultraviolet dye in the oil of the engine (or transmission) and with a UV light detect the source of the leak.
Beyond that I am not much help.

Steven B

Steven,

Do you take great care in centralising the gearbox cover when fitting?
It can move around on the studs before the nuts are tightened.
You may not have the special tool and you would have to devise your own method.

See attached Service Memorandum.


Mick


Mick Anderson

Attached is a page 2 of the Service Memorandum.


Mick


Mick Anderson

Thanks for this Mick,

I did take care when installing the cover, however having said that I did not use a centraliser. It is more than likely that this was my problem.

Is the service tool you refer to available through a commercial supplier? If not I'd be interested in what methods others do to ensure a centralised cover.

Cheers

Steven


S HILL

Steven,

It would be fairly easy to make a centralising tool on a lathe. You just need to take two accurate measurements, the bore into which the seal fits and the diameter of the first motion shaft. It should not be necessary to remove the seal to do that, as the seal is in place when you use the tool. There should be enough of the cover bore protruding past the seal. Just remove the clutch arm.

Ensure that the seal lip is facing the correct way, as stated in the Service Memorandum.


Mick
Mick Anderson

An alternative method is to make sure all the holes for the cover are loose on the studs, and the seal will centre itself. If only one hole is tight on a stud, it will almost certainly be pulling the cover off centre
dominic clancy

OK - now I see the oil! I was looking for a mess like I had when I pulled my engine from the tranny.
Steven B

This thread was discussed on 07/11/2007

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