Garagegods

Hi any experts out there with a 2012 c250 coupe w204 1.8 turbo?

I began to loose coolant a week ago, looked at oil filler cap and had slight mayo more like a latte residue on inside of cap, everything pointed at culprit #1 blown head gasket, car runs great no overheating,no white smoke, no oil in coolant reservoir, I did a basic test with coolant filler cap off running motor and looking for exhaust bubbles Nothing no bubbles??? culprit#2 common problem on c250 oil cooling housing ahaah! well I took it to a certified Mercedes mechanic and replaced the entire oil cooling unit/housing and hoses, changed the oil and seemed to be fine during basic running. Drove car next day on my usual 45 mile drive to work with heater defroster on and looked at coolant level was 1/4 down quite allot? topped off coolant drove the car home with no heater,just AC on checked coolant level after cooled off and NO COOLANT LOSS??? but still frothy stuff on cap and dipstick. Topped off again and drove to work with heater defroster on and cooled down again 1/4 coolant loss ??? WTF??? my question does anyone know of culprit #3,4,5,6??? places coolant can enter engine? any advice would be appreciated

Thank you!

meazz1

Look in the thread, I put a link below.
The coolant pipe is most likely busted and leaking.
Post#12 you see two black pipes , that could be the problem, the metal silver plate underneath where you probably see burnt black stuff, what happen is that plate gets so hot and any coolant on that evaporates real quick, so you don't see any wet stuff.
Coolant Pipe

Odd Piggy

The coolant pipe would account for phantom coolant loss. It’s not uncommon on the C250 M271 engine. But it wouldn't account for signs of moisture in the oil. The trip was 45 miles so short trip moisture accumulation would not be expected.

It wouldn’t hurt to check the heat shield per meazz1’s suggestion for green or brown residue. Sometimes, after the car has been driven far enough to get fully hot and coolant pressure built up, the leak can be seen as steam rising from the pipe or heat shield.

I that turns out to be the problem, it’s a very easy DIY job.

chassis

Head gasket.

Garagegods

😳

Garagegods

I had mechanic #2 replace my oil cooler housing with non OEM aftermarket oil filter housing after the install I was still loosing coolant into motor! took the car to mechanic #3 to find out the newly replaced oil cool housing was leaking again and seems to be the culprit for coolant entering the engine not a head gasket?wtf mechanic #3 tested the block and head and the car passed but they wont positively rule out the head gasket. Also randomly I got a check engine lite and limp mode on my way to mechanic #3 they checked the code and it was not related to other problem it was the high pressure fuel pump.? wtf! i cant win with this car! needless to day I need a car and just purchased this one. I considered trading in to carmax but what they would give me for a trade in and the lowest priced KIA on the lot would cost me more than repairs on the c250! I hope my luck changes soon