Mercedes-Benz W201 head gasket leak: symptoms and oil in the coolant
How can I tell that the W201 head gasket is leaking?
Typical signs are coolant disappearing without a visible leak and white smoke at start-up. Home test: run the engine warm, switch off, wait two minutes and start. If white smoke comes immediately, the gasket is probably leaking.
W201 oil in the coolant, is the head gasket the cause?
Often it is: oil in the coolant points to a head gasket leak. Pale sludge in the expansion tank can come from a leaking oil passage in the gasket. If there is coolant in the oil, the car should not be driven. Brown sludge can also be old oil, corrosion or mixed fluids of different colours.
What else besides the gasket can cause oil and coolant to mix?
The cause can also be the head. The head should be pressure tested at a workshop: a crack reaching the water jacket lets exhaust gases into the cooling system, whereas a crack in an intake or exhaust port does not usually mix oil and coolant. Stretched head bolts are replaced.