'93 300SE - Oil getting into cooling system

[mpayne]

Help. I have a '93 300SE with abouth 70K miles. This has been a very good car with very few problems, until the other day! The oil light came on and stayed on for a few minutes (5 minutes/5 miles) until I got home. The temperature did not rise, the oil pressure was normal and car ran fine. When I got home and opened the hood a found a brown liquid coming out of the radiator overflow. Upon inspection it was oil mixed with anti-freeze. I had the car taken to a local shop (who I have used for years and who primarily deals only with Mercedes) and they thought that the problem was either caused by a bad head gasket or cracked head. The old gasket that they took off looked pretty good so thaey had the head sent to a machine shop to check for cracks. It was machined and came back with a clean bill of health. The gaskets and hoses where replaced, the radiator was flushed and the car was put back together. Everything looked good, no leaks, the car ran extremely smooth, temperature was lilttle less than 80, etc. Life was good. You guessed it...two days and 100 miles later the oil light came on again and when the hood was popped there was that brown liquid again. Any ideas what is causing this? The mechanics are all baffled. They are going to have the head checked one more time, but my gut tells me that is not the problem. ANy and all help would be appreciated.

[Mike Murrell]

Is the shop sure it's not transmission fluid? Tranny cooler lines run through the radiator. Use the search facility. There has been much talk on this subject.

[euro 287]

Could be tranny fluid or oil still in the system. Now you said the oil light came on so I would suspect engine oil, did they replace all of the heater hoses as well as radiator hoses? If not they will burst (trust me) you also will experience mono valve problems down the road. I would flush the system with dawn after replacing (all) hoses. Radiator should have went to radiator shop to be professionally cleaned. We have done alot of 103,119,and 104 motors with this type of problem and learned from past experience. Just my 2 cents.

[engatwork]

I started the procedure for replacing the head gasket on the E320 this morning. Over the past month I have noticed a small amount of oil getting into the coolant reservoir. I will replace the hoses and flush it real good when it is back together.

[mpayne]

Thanks for those that have responded. We are 99.9% sure that it is engine oil and not transmission fluid that is getting into the cooling system. The level of transmission fluid has remained constant while the engine oil level has fallen.

All of the hoses were replaced and the radiator was sent to a radiator shop to be flushed, so hopefully we are good on that front.

The first time that the problem occured the level of engine oil went down relatively fast (5 quarts in about about 10 miles) while the second time it went doen about 1 quart in 100 miles. Could this be telling us something?

Thanks again.....