Internal and External engine oil & coolant leaks can develop from the head gasket and/or timing cover gasket; these leaks should be repaired before the engine oil and coolant intermix which can result in severe engine damage.Google+
Car Problem Reports
Mercedes-Benz SLK230 Repair Leaks From Head Gasket/Timing Cover Gasket Before Oil and Coolant Intermix
Mercedes-Benz SLK230 Problem
Average Mileage: 52,000 mi (12,000 mi - 92,000 mi)
Visitor, 1998 Mercedes-Benz SLK230, 12,000 mi
noticed I was loosing coolant and engine running rough when starting cold. also check engine light came on with cyl 4 misfire. pulled plug with engine cold and noticed water on top of piston.
head gasket needed to be replaced due to rust through. head bolts also need to be replaced at same time, they are not re-usable. this is a typical problem for this engine.