Gearbox Oil Leak

[niainiai]

Hi, I am a new owner with a Mark 2 on which the previous owner lavished £27000 in 6 years! I had no illusions when I bought it that it was in A1 condition, but even so , I have been surprised at the amount of rust and bodged repairs I have found so far. My concern at the moment is the oil that forms a small pool under the car when it is in the garage. From the small amount that I can see when I crawl underneath I don't think that it is the rear oil seal. In fact I think it is coming from higher up around the gear change linkages. I also think that it is leaking when the car is being used and getting thrown around, then dripping down when parked. I don't think it is a blocked breather as I have had a poke around in that. Any idea what the most likely suspects are?

[Ian Durrant]

Is your car a manual overdrive?

[Stagdad]

Some of the bolts that hold the overdrive to the gearbox go through into the oily bits,if solid copper washers haven't been used they can leak from there,amongst other places.cheers Steve

[niainiai]

Is your car a manual overdrive?

Yes, It is a 1974 manual/overdrive with a J-type overdrive.

[Ian Durrant]

Some of the bolts that hold the overdrive to the gearbox go through into the oily bits,if solid copper washers haven't been used they can leak from there,amongst other places.cheers Steve

What he said

[Stagdad]

I have my gearbox out at the moment and what i have noticed is that with the top cover and probably the front nose piece is that some, metal has been pulled up around the bolt holes where they may have been over tightened in the past ,now those gaskets are very thin and i would imagine not able to take up the distortion so i have cleared around the bolt holes with a large drill to make sure.That could have been another leak point ,also front and back shaft seals ,speedo cable output has some orings or seals,orings on selector rods,drain and level plugs ,overdrive sump plate gasket (this was definatly leaking on mine due to a mangled ill fitted filter above it).


Cheers Steve

[niainiai]

I have my gearbox out at the moment and what i have noticed is that with the top cover and probably the front nose piece is that some, metal has been pulled up around the bolt holes where they may have been over tightened in the past ,now those gaskets are very thin and i would imagine not able to take up the distortion so i have cleared around the bolt holes with a large drill to make sure.That could have been another leak point ,also front and back shaft seals ,speedo cable output has some orings or seals,orings on selector rods,drain and level plugs ,overdrive sump plate gasket (this was definatly leaking on mine due to a mangled ill fitted filter above it).


Cheers Steve

I have noticed that the speedo output seems to have some movement and could be contributing but it does look like the oil is coming from higher up. Am I right in thinking that I will have to remove the gearbox to sort it out?
So far everything I have looked at seems to have a problem. I can't believe the previous owner spent £27000 on it in the last 6 years! Perhaps the invoices are fakes.
Anyway I seem to have landed myself with a much more involved restoration than I had planned. I seem to have been down this road before.
Thanks for the advice.

[Ian Durrant]

The trouble with gearbox oil leaks is that the oil seems to get everywhere possibly because the air flow under the car is pretty turbulent and oil gets blown around. if it leaks without the engine running its easier to find. I would thoroughly degrease the whole area and then see if you can see a leak before pulling the box out. My gearbox had a recon overdrive that was missing the copper washers and that was definitely the cause of one of the leaks, I think the breather might be blocked too but I still have too much bodywork to do to worry about that just yet.

As has been said it could be the top cover leaking but that definitely would only leak when the engine was running so if you degrease and leave it and don't run the engine and still get a leak its lower down than the top cover.

[Stagdad]

There is a dye you can add to the oil and it shows up under a UV light.might be worth degreasing the engine and box and then try that if you can't find it.
cheers Steve

[mike@thenook]

Hi,
Welcome to Stag ownership!
I have the same problem and believe it or not the cause is a dodgy rear oil seal on the overdrive unit;
I say believe it or not because this was a re-con unit from a well known supplier but the rear oil seal has always leaked and deposits oil on the exhaust which smells horrible when it gets hot!
I will one day replace the seal, its not worth taking the whole unit out and asking for another because the other may well have the same problem and they are a bugger to get out without gearbox removal.
I suggest you get the whole gearbox area cleaned with a good engine cleaner and warm water (you cant beat Autoglym) then run it to see where the leaks are. It may well be loose bolts, the o/d unit does leak if all the bolts aren't well tightened so it's worth checking all are done up. The other culprit can be the speedo drive housing - there are two seals in that plug ( one on the housing and one on the drive shaft) and they can both produce a nice leak.
If ever you are over this way (near Brentwood Essex) I'd be happy to have a look for you, been there and got the tee shirt so to speak so if I can give any pointers....