I am going to look at a 1991 300E 2.6 later today. The owner states that the car has just recently (since last Friday) started running hot (120 degrees) about 10 minutes after driving. He believes the heater core is on its way out. The AC still works. His wife drives the car everyday on a 20 min. commute. Will driving the car everyday at this temp detonate the engine? He states that the car does not overheat, only runs hot. Does this sound like a heater core or possibly a greater problem.
The car is going for $500 because of the difficulty in a heater core replacement. I am not scared of this DIY (even though I should be).
What are your thoughts?