W124 300Ce coupe gearbox

[Adeinfrance]

Hi. I have a problem with my 300CE auto gearbox. When the box is full of oil it drives superb but on a long run throws the oil out. When the oil has gone it still, amazingly, drives and changes correctly although a bit lumpier. The box has done 190K unless it was changed before I bought the car 12 years ago with 140K showing. Has anybody experienced this before or does anybody know what the problem might be? The problem seemed to start after having an 85K engine fitted but I can't be sure. It has been suggested that I change the filter and oil. I need to drive the car back to England soon and although it has made this journey twice before in this condition I am now beginning to worry about blowing the box up. I am not a mechanic but surely if the box is changing correctly in all gears when it should there can't be a lot wrong with it can there?

 

[krimat2005]

are you checking level after short drive (10miles) with the engine running? this is how you should do it.

 

[Adeinfrance]

Yes. I live in France and there is a great English mechanic who has checked the oil correctly. Last time I drove it back to Uk it was fine until after 500miles and I saw a lot of smoke coming from the back. The oil from the gearbox had made it's way underneath the car until it reached the rear box and started burning. IWhen I pulled in I thought the car was on fire for a moment!

 

[Vlad]

Are you sure its not rotting transmission oil cooler pipes?

 

[Adeinfrance]

Not sure. People who have looked at the car have said it's difficult to see exactly where it's coming from. Perhaps I should try and find someone to clean it all off then leave it running for ages. Still seems weird that the problem seemed to start after the other engine was fitted.

 

[Vlad]

The cooler pipes for the transmission get very rusty on these cars as they sit low down under the car and get all of the road crud thrown up at them.

They tend to get thinner and thinner as they rust away and eventually they burst and if you don't catch it in time you will wreck your box....thats assuming that its the pipes that are at fault.

I would get the underside jet washed off and then take a close look at the pipes going to the radiator at the front of the car.

 

[millo777]

I would imagine a lot things get disturbed and moved around when a new engine is fitted so it's not that unlikely that something could have happened at that time.

I'd try and get the underside steam cleaned to make it easier to see where the leak is coming from.

If that fails, a mechanic should be able to add some tracer dye to the fluid to aid finding the leak.

 

[Ian B Walker]

I would look at the banjo joints of the atf lines to gearbox, maybe the aluminium washers have either corroded or not been fitted.

 

[Adeinfrance]

That's great advice. Thanks to everyone. I am also looking for a rear screen for my coupe if anyone knows a car being broken but I know they don't come out that easily. If any mechanics fancy a weekend in the south of France sorting my gearbox leak out let me know.