Oil Leak Identification, Where's the oil leaking from?

My 2.1 TD has developed a slow oil leak which appears as a widespread oily coating of everything below and behind the gearbox - good for rust prevention!, but leaves a messy oily stain or two as it drips off the subframe (no undershield) wherever I park. No discernable change in gearbox / LHM reservoir / engine levels can be seen in the short term.

At first I thought it was the nearside drive shaft seal into the diff but after fitting a new seal the leak is still there. A high pressure LHM leak would no doubt rapidly leave a big green puddle so I don't think this is the culprit. An LHM return line leak is a possibility but as far as I can see the rubber lines are in good nick and I can't see any green colouring the leaked oil. That leaves the worrying possibility that it could be either the gearbox input shaft seal or the crankshaft seal that is failing.

Removing the small inspection plate on the bell housing didn't reveal any oil staining on the edge of the flywheel and the clutch operation is normal so I'm coming to the conclusion that the leak could be from the gearbox input seal.

I will be pleased to hear comments on my diagnosis and/or other member's experiences in this area. Also does anyone know if this gearbox has any sort of breather fitted or is it sealed?

Regards

Ken

Been there last month. The first thing to identify is the actual oil colour. Excluding the green LHM (and not leaky hydraulic system would greatly simplify the diagnosis), if the oil is thick and black than it's the gearbox. In my case it was the seal on the LH shaft. Underneath, the car is oily and wet on a large surface from middle to the left side but you might find just a drop or two overnight on the path which might mislead you to think it is just a minor leak. I lost half of my gearbox oil like this. IMHO, it must be a seal somewhere because the rotating part spreads the oil around.

This post has been edited by John Malkovich on July 01, 2008 02:36 pm

Hi Ken

If its gearbox oil it will smell like cats, its more likely to be engine oil leaking from the rocker cover gasket.

If your gearbox oil is black John, you are in serious need of a service!

Peter.N.

It' new now.
However, I don't know many people who have ever replaced the gearbox oil in their car lifetime.

Fairly important if its auto though , Best way to go is steam clean the underside of the car or degreaser would be a lot easyer, and it will make tracing the leak easy................it will ruin your anti corrosion coating though

Regards D

I shall be on the one am presently fitting a clutch to, when I took the driveshafts out no oil followed

i did have it done in my Prestige in 2001.It was a bit "stinky" apparently.

that car btw has always used oil since i got it , 10 years and almot 50k ago.

An update to my 2.1TD gearbox oil leakage problem.

I discovered that there is a breather on the box which consists of a screwed plastic plug (~25mm diam) with a ~1.5mm hole in the middle. It is located at the front / top of the box, almost out of sight under the clutch operating lever. There is a square recess in the plug so that it can be removed using the same size square drive tool that is used for the oil filler plug. In my case the plug recess was totally full of solid black gunge thus blocking the breather hole. Since cleaning the plug I have checked the gearbox oil level several times and the level has remained normal.

The only explanation I can think of is that the box may have been getting slightly pressurised when hot causing oil to be forced out past the nearside shaft seal.

Ken

Sounds feasable