Leak between engine and gearbox.

[michael113]

I have a manual 230sl. There is an oil leak between the engine and gearbox. I got a quote to fix it for a lot of money, they are saying that in order to fix it the engine would have to come out, and the crank would have to be re balanced.

This sounds excessive to me, does anyone have any ideas ?

[George Des]

It sounds like it is a rear main seal on the engine although it could also be the front seal on the gearbox. Make sure it is engine oil and not transmission fluid. The mechanic is correct that the engine or transmission will need to come out depending upon which is leaking. The only way to change out the rear main seal on the engine is to drop the entire oil pan assembly once the engine is out--not just the sheet metal portion and to lift out the crankshaft to get at the rear main seal. I had to have this job done many years ago in Germany on my M127 engine.  Not sure why the shaft would have to be rebalanced however as nothing on the shaft needs to be changed that would affect the balance. I understand rear mains on US built engines of the past could be done fairly easily by snaking the rear main seal up and around the shaft with something called a "Chinese Finger". With the Mercedes engine there is a tab or spike that would prevent this from working as far as I know. Hope this helps.

George

[jameshoward]

I'd agree with George, in that you may find it's Automatic Transmission Fluid (ATF). I'd also echo the question about why the crank would need balanacing.

Depending on how bad the leak is, I'd be tempted to live with it. You could throw a bottle of seal conditioner in the gear box. I had a similar issue and this helped. Unless the leak is substantial, you'd probably be better off waiting until you really need to remove the engine. (Any maybe find a different garage to do the work!)

[michael113]

Thanks for the reply.  The engine was out, as I had all the pipework re plated, and the entire engine detailed while the car went away to have the inner bonnet re painted, which was an expensive job. I asked for the leak to be sorted beforehand.

When it was still leaking when I collected it  he told me he hadn't done it because of the shaft having to be re balanced and it would have costed an additional £4000.00 ?? It is an engine oil leak between engine and gearbox.

What do you think ?

[michael113]

Thanks for the reply.  The engine was out, as I had all the pipework re plated, and the entire engine detailed while the car went away to have the inner bonnet re painted, which was an expensive job. I asked for the leak to be sorted beforehand.

When it was still leaking when I collected it  he told me he hadn't done it because of the shaft having to be re balanced and it would have costed an additional £4000.00 ?? It is an engine oil leak between engine and gearbox.

What do you think ?

[George Des]

I'd find another garage. The only thing he needs to do is remove the bearing caps and lift out the entire crank assembly, replace the rear main, put the crank back in place and retorque all the bearing caps. It may be a good idea to check the bearings but there should be no reason to rebalance unles the crank and/or flywheel is recut or reground.

[jameshoward]

I think that £4000 to do that is a good wage.

There would be no need to rebalance the shaft at all, unless I'm missing something. (Has been known). If you asked them to fix the leak and they didn't, I think you have cause for a conversation with the garage. However, by quoting an absurd cost like that, it seems pretty clear that the guy doesn't want to go there.

Do a search on the site for similar issues, or read Andy Burns 'blog/biopic'. I think that Andy had to do something that involved separating the box from the engine.

Again, are you absolutely 100% certain that it isn't ATF, as in you've really checked the colour, and know exactly where it is coming from? Speaking from experience, it is very hard at times to discern exactly from where the leak may eminiate.

Worth a second look. Then maybe a chat to your mechanic.

Others who have tackled this may have better advice. I just live with a small leak.

[ja17]

The crankshaft should not need to be re-balanced. The short fix is to just replace the lower half of the seal which wears the most. In this way the crankshaft will not have to come out and the transmission can be left in place. However the time to do it was when the engine was out, since you cannot remove the oil pan without removing the front suspension or removing the engine now. Replacing the bottom half of the seal often times cures most of the leakage.