Leaking gearbox seal?

[Trigbush]

So I have parked the car a few times in the garage and noticed some fresh oil forming in patches under the middle of the car. Today - as I had some time - I managed to crawl under the car and have a look. I also took some photos. Attached (I rotated photos but they may have loaded back in original position).

The freshest patch (smaller than an older one - about 8 inches across - as seen in Photo 3) appears to be directly under the rear of the gear box flange where it meets the front of the propeller shaft front end. I wonder if the rear oil seal in the rear extension is leaking?

Does this look like it? Grateful for your thoughts.

Cheers


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[mike@thenook]

Hi,

Mine leaks there too, its' the seal at the end of the overdrive housing where the front flange is. The annoying thing is that on the od unit I replaced that seal didn't leak but on my current re-con one it has from day one - dammed annoying but I just could not bother complaining and having to take out and fit another unit so, now I have a new prop to fit too, I will replace the seal myself, I bought one from LD some months back as I know they are excellent on getting reliable parts.

What I really hate apart from the small loss of oil is the smell it makes burning on the exhaust!

Cheers

[Trigbush]

Thanks Mike. That sounds painful.

I have a J-Type OD. I am not keen on this news...is the amount of oil on the floor significant in your view? I.e. do you think I need to change the seal as the leak is considerable or do you think it can be left and the oil simply topped up?

Cheers

[mike@thenook]

Yes - mine is J-type too.

Two minds really - topping up is not an easy job to do on a weekly basis unless you do what some do and enlarge the inspection plate under the carpet LH tunnel side so you can top up from inside the car otherwise it's an on the ramp and under the car job - not what i'm keen on these days.
The other point is the smell of the hot oil (which is an aquired taste).
Certainly it looks like you have a lot more oil coming out than mine, which is just a drip really when its running, none at rest so I hate to say it but it looks like replacement is your best option.
Getting the back nut undone on the driveshaft flange can be tricky - it is a highly torqued one and it is not that easy to get a long bar on it unless the car is on a high lift ramp. If you have an air wrench this might make it easier though.
Having said all this and before you start doing the job I would clean the area around the box completely then run it warm & see if you can detect the seal leaking with the engine running, it doesnt't need to be in gear but if that seal is the culprit your will be able to feel the oil with your finger between it and the flange.
Otherwise it may just be getting blown out under pressure because the oil breather hole is blocked, another bugger to get to without a small mirror and a piece of thin but strong wire to clean it out. If this is blocked it can cause the oil to leak out of the top of the box which then runs down the back and onto the exhaust/floor etc.
If you search for gearbox breather on here you'll get the drift...

Hope this helps

[Marco Polo]

Topping up the gear box is made easier if you use a funnel, a length of garden hose, a 90 deg. plumbing fitting and a couple of hose clamps. Undo the gearbox level plug from the box run the hose down the side of the box from inside the engine bay, push the 90 deg. fitting into the level/fill hole, it fits perfectly! Fill the box from inside the engine bay using the funnel, I've been doing it for years to refill gearboxes on all makes of cars. Works a treat!
Regards,
Raoul

[Trigbush]

Thanks Mike and Raoul. I clearly need to give this some thought...

[mike@thenook]

Topping up the gear box is made easier if you use a funnel, a length of garden hose, a 90 deg. plumbing fitting and a couple of hose clamps. Undo the gearbox level plug from the box run the hose down the side of the box from inside the engine bay, push the 90 deg. fitting into the level/fill hole, it fits perfectly! Fill the box from inside the engine bay using the funnel, I've been doing it for years to refill gearboxes on all makes of cars. Works a treat!
Regards,
Raoul

This is just how I do mine but you still need to get under the car to undo the plug in the first place

[Trigbush]

After some examination and consultation I am pretty sure that the oil leak is from the gearbox selector rail oil seals (the regular ‘o’ rings on the remote selector housing). I know this is a very common leak spot, which only occurs when the car has been running with the overdrive engaged, as this increases the pressure inside the gearbox. I understand the only solution is to remove the gearbox and dismantle the selector housing to replace the seals and ensure the breather is clear.

As long as the overdrive continues to work I am sure I will be fine....and I hope to manage until the next service. I am reluctant to explore more now because I know that to replace these seals you need to drop the gearbox and dismantle the selector housing (which must be about a total of 10 hours work for a professional).

So I am going to drive carefully (or more carefully than normal)!