Oil leak - Where is it coming from?

[SuperCNJ]

Just wondering if anyone can help with this as I'm quite confused at the moment.

There is some "sweating" on the entire gearbox casing and a small amount of oil accumulating on the bottom of the seam between the gearbox and the engine block. I've checked the engine oil and gearbox oil levels and there is no loss of oil at all.

Does anyone know where this oil could be coming from? This is for a manual GD Sport.

Many thanks! 

[SuperCNJ]

Here is a photo taken from the engine bay. To the left is the engine, the right is the gear box (I believe) - which seems to be covered in film of oil.

[Jocko]

It looks to me as if the gearbox has been replaced at sometime (common on a Mk 1), and it is just a dirty gearbox. Leaking oil doesn't normally give such a uniform covering. Personally I wouldn't worry about it.

[SuperCNJ]

Yes we had a gearbox bearing replaced a few years ago but I have checked the gearbox oil level and you couldn't put another drop in (it's that full!) but there is a few drops of oil on the underside of that seal for some reason.

Here is another photo of the underside.

[Ralph]

Here is a photo taken from the engine bay. To the left is the engine, the right is the gear box (I believe) - which seems to be covered in film of oil.

If you zoom in to the left of the photo below the large rubber hose there’s a small open ended breather pipe that seams to have a small drip coming from it could this be the “leak” ?

[sparky Paul]

If you have a drip of oil forming, get some on your fingers, rub it around to warm it up and smell it. Hypoid gear oil has a very 'distinctive' pong, as indeed does clutch fluid. Engine oil just smells 'oily'.

[SuperCNJ]

Here is a photo taken from the engine bay. To the left is the engine, the right is the gear box (I believe) - which seems to be covered in film of oil.

If you zoom in to the left of the photo below the large rubber hose there’s a small open ended breather pipe that seams to have a small drip coming from it could this be the “leak” ?

Thanks, I never spotted that. But there doesn't seem to be any oil directly underneath that breather pipe?

[SuperCNJ]

If you have a drip of oil forming, get some on your fingers, rub it around to warm it up and smell it. Hypoid gear oil has a very 'distinctive' pong, as indeed does clutch fluid. Engine oil just smells 'oily'.

I'll give it a go but as the gearbox is completely full of oil, and so is the engine, I'm guessing it isn't that.

Clutch fluid? That sounds possible. Any idea if there is a bleed nipple for the clutch fluid in that area?

[sparky Paul]

If you have a drip of oil forming, get some on your fingers, rub it around to warm it up and smell it. Hypoid gear oil has a very 'distinctive' pong, as indeed does clutch fluid. Engine oil just smells 'oily'.

I'll give it a go but as the gearbox is completely full of oil, and so is the engine, I'm guessing it isn't that.

Clutch fluid? That sounds possible. Any idea if there is a bleed nipple for the clutch fluid in that area?

You need very little oil to completely wet a gearbox or sump, it wicks around the casting and makes it look like it's coming from elsewhere.

The clutch slave cylinder and bleed nipple is above the front of the bell housing, between the starter motor  and the air filter box. If you're loosing clutch fluid, you soon run into problems, I would guess it's probably not that.

[SuperCNJ]

Thanks.

Do you know if there’s a way to check if the clutch fluid is low? Is there a reservoir somewhere?

[culzean]

Clutch fluid reservoir should be right next to the one for brakes if your car is a manual gearbox one.

[SuperCNJ]

Clutch fluid reservoir should be right next to the one for brakes if your car is a manual gearbox one.

Ok, I've checked the clutch fluid reservoir which is just a few millimetres shy of the maximum level. So I'm guessing it isn't that either?

Really odd. 

[Jocko]

As I said earlier, the gearbox looks like it has been dirty for years. I wouldn't worry about it.

[SuperCNJ]

As I said earlier, the gearbox looks like it has been dirty for years. I wouldn't worry about it.

Thanks. I guess it's just seems strange that it is only on the gearbox casing and nothing else, almost like the casing is porous! If there wasn't a small collection of oil at the seam I wouldn't be so concerned.

I might just have it checked at the next service then. Thanks again!

[sparky Paul]

I guess it's just seems strange that it is only on the gearbox casing and nothing else, almost like the casing is porous! If there wasn't a small collection of oil at the seam I wouldn't be so concerned.

It's just finding the lowest point. You might have a bit if a weep from a gasket, but if it's not dripping, as Jocko says, it's nothing to worry about. If it was coming from inside the bell housing, you might have had a problem, but it's not a major issue where it is.

Have you checked around the driveshaft seals? Are either of those wet, particularly the nearside? That's a reasonably common leak point for gearbox oil, and not too bad a job to rectify.

If it is a gearbox gasket, fixing it would be more trouble than it's worth, unless it was leaving oil on the driveway.