Hi,

This is a high mileage 2012 mk3, 1.6 tdci with manual gearbox.

It is leaking what I think is gearbox oil, the oil is completely clean, doesn't smell like old school EP90 gear oil. Around a couple of tablespoons overnight. I can see it drips from the lowest part of the gearbox, in front of the drive shafts. The bottom of the gearbox is oily, but the passenger side is not. I can't see the driver's side until I lift the car up or take the wheels off or something.

Any pointers on how to track it down, the most likely sources?

Thanks.

Gear oil smells awful, I wonder if it's clutch fluid instead?

We would really need to a see a picture to determine where it's coming from.

Thanks. The oil is dropping from the highlighted area. I think it's coming down from behind because if I reach my hand there I get clean oil. If I touch round the drive shafts there's the barest trace, but it's dirty.

 

 

Thanks.  I'm not sure that picture is as effective as I was hoping for unfortunately.

There isn't really anything on the back of the gearbox that can leak so it's an odd one.  A picture behind the gearbox may help but I appreciate that's likely to be impractical.

It could be diesel.  There is a drain pipe from the bottom of the fuel filter which comes out behind the gearbox.  Maybe that would be a good place to start checking as you can access it without jacking the car up.

Is there no smell or colour to the oil? If diesel you would smell it. Any fluid levels low like brake fluid or coolant?

Thanks, definitely not Diesel, I'd recognise that immediately. The smell is sort of bitter, colour is pale amber. It's the same sort of consistency and colour as engine oil, but doesn't smell like. Also oil leaking from a Diesel wouldn't be that clean.

Could it be brake/clutch fluid? I think it's thicker but there's not much in it. Smell is sort of similar. The reservoir is right up to max.

Definitely doesn't smell like old school EP90 gear oil.

I need to work out how to get underneath. There's not enough clearance for wheel ramps. Or even for my trolley jack to get under the jacking points. 

Actually I'm not even sure where you'd lift with a trolley jack, do you put it under the same vertical rib that the emergency jack uses?

I think what I'd have to do is drive the front wheels onto a couple of planks to get a bit more clearance, the see if I can jack it up enough to put the ramps under the wheels.

Re jacking it up. Use your standard scissor jack, obviously one side at a time, to get the initial clearance for your trolley jack/axle supports/ramps (as preferred).

Works for me 😋

I bought a low entry trolley jack about 10 years ago.  Never failed to get under any car!  Either used the sill points or the subframe.

The colour and viscosity do sound like brake/clutch fluid.  But even that has a distinctive smell.

If it's old and absorbed a lot of water then it can be thinner than expected.

Another option I thought about for that area would be the EGR cooler leaking coolant.  Can feel surprisingly oily compared to plain water.

Thanks.  I really can't decide if it's the same as the brake/clutch fluid or not.  There's also the question of where it would be coming from, since maybe 100 ml or more has leaked out, yet the reservoir is full and brakes and clutch all work normally.

Looking from the passenger's side with the car raised and the wheel removed, it almost looks as if bolts are missing from the transmission.  Not sure what you call that part, where the drive shafts connect and presumably the differential is housed.  See photos, should there be bolts there ..

 

 

Well, I think you've found the culprit! 😮

I'll bet that's a 'reconditioned' gearbox just been fitted.

There is no other reason to remove those bolts.

 

Good, or is it?

I wonder if replacing those is going to fix it, or whether transmission needs to be torn down and rebuilt with new gaskets.

Gets some bolts in and try it. Check and top the fluid up. 

Right, there are five missing(!) that I can see.

I've popped in the only thing I have to hand which was cap head Allen screw with a washer. At least that tells the correct size. ideal as they're fully threaded and A2 stainless. But I thought better to get it clamped up sooner rather than later.

We'll see if that stops the leak.

Is it worth getting the correct Ford bolts or would standard flange head be OK? I can't see they need to be more than 8.8 as they're threaded into alloy.

For example ..

FLANGED HEXAGON BOLTS 8.8

By the way, what's the correct oil level? Is it supposed to be level with the bottom of the filler cap? (Front of gearbox, takes 8mm Allen key.) I've seen some references to filling to that level, then drawing off a stated volume.

This is six speed manual.