Hi guys

First of all i want to apology for my bad English, i hope to be understood. I want your help and your opinion( even i the problem is obvious, you will understand when you read )

A friend has a w203 C180 with M271 engine with manual transmission. My friend comlained that he didn't have hot air in the cabin even when the car had 80+ degree water temperature. In the test drive i saw that the temperature falls to 60, so it was (and) a thermostat problem. When i open the hood i saw engine oil in the coolant reservoir tank. It wasn't mayonnaise colour that indicates head gasket problem. It was black colour, sits on top, and it wasn't mixed with coolant. The car has no idling problems, no overheating and as i can understand no "strange" exhaust gas colour[not sure]. So i tell him to take a look daily at the coolant tank. The next day he goes a trip and he get a message for low coolant. He fill about 400ml of clean water and he came back. After 2-3 days we saw the oil in the coolant tank was double (about 3cm height) and he get the low coolant message again. He fill about 500ml of water. After an internet search I said him that the problem might be the oil cooler (heat exchanger ) or/and the two gaskets in the oil filter housing. The one between the housing and the oil cooler and the other between housing and block. We have started the DIY job in Saturday morning, but the oil cooler didn't arrive the afternoon as the dealer said, and my friend decided to put the old one after I “check” it , because he wanted the car. The condition of the oil cooler wasn't the best. After cleaning i saw that around the two holes that pass coolant, has some corrosion spots and maybe that was the problem. I did a "pressure test"(If you can say that), from an air compressor, about 7 bar air through oil passes and water passes. It seems like it has not leakage between them. [not sure of curse]. We also grind the whole surface of the oil cooler so that the spots disappear [It was 90% improved]. I put oil in the gasket between oil cooler and housing and the stamp that did in the oil cooler surface looks ok (the spots that remain where inside the gasket and the oil passes seams that sealed with the gasket. Also, i check the oil cooler surface for flatness (because of grinding) and looks ok. We also do a thermostat replacement and engine coolant flush.
Everything was fine for a week and then we saw again oil in the coolant tank. Again, my friend fills coolant. In my opinion the problem persists in the oil cooler (maybe a pass inside or at gaskets) but if it's not there, what are the other scenarios? Where the leakage can happen and where the coolant goes? Doesn’t have obvious external leakage.

Ps1.A little amount of oil exists in the compressor air lines (from intercooler to intake) and between inlet manifold and head.

Ps2. The camshaft adjusters have been changed before 7k km. Not sure what the mechanic knew about this engines.

Some photos









Thanks

 

Any suggestions?

 

Update!
99% the oil that appear again was the remaining in the cooling system. It's been ten days and the amount is still the same. So, everything is ok

 

bro what was the issue, did you get it resolved cuz I'm have the same issue with my e200 m271

 

Thats just the m271 doing it's thang, gurl. Don't be mad. It is what it is.