2004 c240 4matic 47000 miles, one day after change oil in local auto mechanic shop I found a oil spot under engine. How to found out, this is motor oil or automatic transmission fluid?

 

Not meaning to be an ***, but you need to remove the under engine plastic shields and look to see if it from transmission or engine.

 

Thank you for your concern. Mechanic remove the shield and oil (with the consistence and look like fresh motor oil) was all over on engine and transmission pan. Mechanic stated, this is a transmission pen gasket leek and have to be change for $385! Always I thought transmission fluid is reddish not brownish like motor oil. I thing mechanic just play a game.

 

Maybe the mechanic was just sloppy. Wipe up the puddles and wet spots and see if anything else appears. Hard to diagnose when there's fluid everywhere.

 

I had the same issue last year in December and got everything resolved this month. My suggestion is to get your motor and bottom of the car steamed cleaned if you can. This really helped me and my mechanic determine where my oil leak came from. The car I have is a different car than yours. I have a 2005 C230 sport sedan Kompressor. I had oil all over the front of the motor and it turned out to be my camshaft solenoid magnet. Upon further inspection, we found another leak relating to my tranny. A 13 pin connector was leaking tranny fluid. Changed out everything with new seals along with a complete overhaul and tune-up of the whole engine and tranny. Car runs smooth and brand new again. Good luck.

 

$385 just to replace the transmission pan gasket?

I could change it in about 20 min plus $13 for the gasket, assuming reusing the old fluid. If you do a full flush the fluid and filter cost about $120, and it will take an hour or so.

Paying someone every time it needs work will approach the monthly cost of a new car. Keeping an old one going implies DIY as much as possible.

 

The tranny has this piece that is a 13-pin connector that it fits into and it's common for it to leak. Mercedes has since fixed this with an updated piece. It is called a pilot bushing although it has no resemblance of a manual trans pilot bushing. I would get this piece from the dealer, I can give you the part number tomorrow (I have it down in the garage). Cost from the dealer is $28 (I was surprised it cost that little, being from the dealer!!). It's not hard to change and you don't really have to drain the pan or anything, there may be some fluid seeping out but not much. Someone has actually done a step-by-step somewhere already and I can try to find it if you're interested.

 

Thanks for the 411 on the 13 pin connector. We've changed this out once we found out the leak. I paid the same price at the dealer as well; $28.00.

 

Thank you, but how can I find out, it is transmission fluid or motor oil?

 

If you can't tell by the color (which for tranny will be a deep crimson color (used) you can tell by the smell. The color may change but the smell will be the same. If you're not sure you can always open the oil cap from the engine and that's what the oil smells like. If the leaking fluid doesn't smell like that then it's the transmission fluid.

 

You wright,
Thank you