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MG MGA - Leak from gearbox front cover

Folks, about 1500 miles following a full restoration my 1600MKI started leaking gear oil from the bellhousing split pin. I begrudungly removed the engine and renewed the front cover gasket and oil seal with the gearbox in situ, this time with the aid of the centraliser tool that I had a local engineering workshop make up for me.

To my disappointment I'm still experiencing a slow but persistent drip of gear oil from the bellhousing. The attached photo shows the amount of oil collected over a 4 week period when the car was sitting idle (approx 2-3 table spoons worth I'm guessing).

My question is, is this excessive? And is there anything else I can do/check to help stop the leak?

Cheers

Steven

STEVEN HILL

Assuming it was originally gearbox oil is it now engine oil?

Steve

Steve Gyles

As Steve says, you have to determine if it is gearbox oil or engine oil.
The leak does seem excessive.
I find that engine oil darkens enough after a fair bit of use to give it a slightly darker colour than gearbox oil.
Gearbox oil seems to retain that "honey" colour even after many miles of use.
Also if held up to the light used gearbox oil can give a slight golden sparkle from small traces of suspended metal particles (from the synchros).
Leaking gearbox oil tends to run down the bellhousing to the drain, but engine oil is thrown off the flywheel. Can you remove the starter motor and get a reasonable view of the flywheel?
If it is a gearbox seal problem see if you can find a late model 1600 MK11 front cover with the proper oil seal.
See:
http://www.mgaguru.com/mgtech/gearbox/gt101.htm

Mick
M F Anderson

Thanks guys. It's definitely gear oil. Here's a picture of what I found the first time I removed the engine. You can see traces of oil on the clutch fork bolt head. I'm presuming oil was running pass the rubber oil seal.

Cheers

Steven

STEVEN HILL

Have you checked the breather on the gearbox housing before fitting the unit back on? With a blocked breather excessive pressure is created inside the box resulting in blown gaskets and/or oil seals.
F. Camilleri

Steven, I wouldn't have thought that the oil level in the gearbox should be high enough for it to leak past the shaft seal while at rest. Could it be that the gearbox oil level is too high? Have you got the correct gearbox dipstick, or is the dipstick bung not going far enough into the casing apperture?
Lindsay Sampford

This is what my gearbox dipstick looks like.

Lindsay Sampford

"Full" level of oil in the gearbox is below the front seal, about at the top of the hub of the laygear. If any significant amount of oil leaks out when standing still, it is more likely leaking at the paper gasket joint. You definitely need to get the right amount of shims between the front bearing outer race front cover. Too few shims allows the front bearing to float fore and aft in the alloy housing. To many shims will prevent the paper gasket from sealing.
Barney Gaylord

Thanks guys. It sounds like the leak is excessive. My Gearbox dipstick is the right one and it's fully seated. I'll check the breather on the weekend provided I can get to it. I'm anticipating it's not going to be easy to access from under or inside the car! Otherwise I guess its engine out (again).

Cheers

Steven

STEVEN HILL

Not such a chore when you've got a garage as nice as that Steven! As Barney suggests, it must be something to do with the cover gasket, as the oil level is well below the shaft seal.
Lindsay Sampford

This thread was discussed between 17/07/2011 and 18/07/2011

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