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I have a German VW Beetle gearbox (AB Code) that was recently rebuilt as a 4.12.

The box is leaking gearbox oil from the bell housing between the gearbox and engine so I thought there must be a faulty seal.

I have replaced the drive shaft seal twice and the leak is still there. I used an original VW seal the first time and then an Elring seal the second time and nothing seems to work.

I checked that the drive shaft was perfectly smooth (it is) and made sure there was not a groove cut into it from wear. I also cleaned out the area where the seal sits and used Permatex on the outside of the seal and a little gearbox oil on the inside - none of this has worked.

Does anyone have any other ideas of what I can do or check - it's driving me crazy and ruining my drive way!

Hello Paul,
maybe not the seal is the problem.
You migth get this also if you have to much oil in the box or the the small hole for the preassure compensation is closed for whatever reason ....

Hi Manfred,

Thank you for this. Do you know if this hole can be accessed unblocked/cleaned without removing the gearbox?

P

I never tried this, but you should get a view on it above the selector shift from front to rear. I don't think with your eyes, your head meigth be a bit to big, but wih a mirror our a smartpone our camera.
I just saw that there could be a seal in it (scroll the pic.). I don't had one when i replaced the gearshift housing years ago.

Great - thank you Manfred - will have a look and see what I can find tomorrow.

The small hole is for venting the gear box. Overpressure...

You can mount a small hose made of copper, stainless steel or plastic or rubber... and so the opening is higher and not leaking oil when the gearbox is parked on a hill.

The oil is leaking from the rear oil seal between the engine and the gearbox. It is not engine oil - definitely gearbox oil and the seal has been replaced twice.

Manfred thinks that pressure might be trapped in the case because the hole at the front is blocked so tonight I will try to clear the hole with a compressor.

I think it would be better to open the oil-inlet-screw of the gearbox before using the compressor, so the air could diassapear.