1993 300SE Oil in cooling system
 

I just picked up my car from the mechanic after having my head gasket replaced. I got home and looked in the coolant tank and again it is brown. Before replacing the head gasket he tested the oil heat exchanger and it checked good. Does anyone have any suggestions on what to check next?
I have a 1993 300SE W140.

HELP!!!
Gil

I assume that you had cross-contamination beforehand? If so, did your mechanic flush out the cooling system? If not, there is very likely to be oil residue turning up in your bottle for quite some time to come.

He said he did flush it out a couple times. He also said that it is real difficult to clean out and that I would have to flush it out a few more times myself but even after that there may still be some residue in the system. Before I took it in I also drained and filled the system several times.

Mb recommends shout to flush out the cooling systems.. buy a Big bottle and use that over 2-3 flushes. Be sure you have the t-stat out and ideally you want to open the block drain @ the same time.

Jonathan

Gil, if I were you I would insist the mechanic complete the head gasket replacement and thoroughly clean the cooling system. There's no way you should need to get involved after paying him to replace the head gasket. How many owners would even know how to flush the cooling system? The mechanic should have allowed for cooling system flushing in his estimate.

The "heat exchanger" is most likely the problem.

Was it removed & pressure tested?

99% of the time on that model, THAT is the problem.

Thank you all for your responses. Today I am going to research finding a heat exchanger and possibly replacing the part myself. The reason I took the car to this mechanic was he suggested the heat exchanger might be the problem and would look at that first. He apparently removed and pressure tested and it checked good. How does it get pressure tested? He said he put it under water and looked for bubbles.

UPDATE: I flushed the cooling system 4 times and after every flush there was still oil in the coolant. I checked the oil level and it is lower than when I started. I believe as MB DOC suggested that the heat exchanger is the problem assuming the head gasket replacement was done properly. I am having trouble locating a heat exchanger online. Does anyone have a part number that I can use to search online?

Thanks.

Gil, recommend trying a salvage yard or your local MB dealer for a replacement heat exchanger.

Time to consider switching mechanics if the head gasket replacement was unnecessary. Finding an indy with excellent diagnostic skills and intimately familiar/trained to work on MB automobiles can be difficult.

We are just going to remove the heat exchanger and make a blanking plate for the cover.
A new heat exchanger is going to be expensive and does this motor really need it?

I suspect it is more of a oil heater in cold climates.

MB number is 104-180-03-09

to the original poster-it is not an oil heater, it's an oil COOLER. do not block it off. it has a job to do. good luck, chuck.

M103 engines don't use it.
Oil works better if its hotter, synthetics are happy up to 150deg c.

We just finished removing the heat exchanger and fitted a 6mm plate under the cover and the oil pressure is fine.

If you're adamant you want an oil cooler then fit a common air to liquid cooler.

any photos of the job? Just would be curious to See what ya'll did:)

I think in proper conditions, ie the Autobahn where one would/could be turning very high RPM for extended periods the cooler would be greater importance. The vast majority of us likely don't tax our mercs quite that hard;-)

Jonathan

No, we didn't take any photos.
Pretty straight forward though.
This twin cam used the 104 180 02 09 heat exchanger and is hard to find online and I would expect it to be expensive at the dealer.
Also downtime was a factor. Using the plate got the car back on the road same day and oil in the coolant isn't coming back again.
I don't expect there to be any problems, like you say in extreme circumstances like constant high speed running it maybe doing something.