I have found heavy leak of engine oil into the radiator of my 1996 Mercedes Benz (odometer 150000 mile). The workshop found the oil cooler pump damaged but we could not find a new one in the area. He suggested to run the car without it (temperature was around 70 F).

He informed me that he cleaned the passage of the coolant in the engine but I should expect some oil in the radiator for three days after cleaning and I can remove it by opening the cap and use some tissue to remove it. I used the tissue to remove the oil daily for about two weeks, then I gave up and I removed the oil weekly instead of daily.

After about three months from cleaning (after about 3500 miles), I discovered radiator coolant leakage. I checked the car in the same workshop. They found the leak from the water pump and the bottom of the radiator. My intuition says that the leak is due to the oil in the coolant system. They say that the oil in the coolant system is not the cause. Can you please tell if there is a cause and effect situation here and should I ask them to replace the hoses or just clean them.

1 Answer 1


I'm not sure you should trust to intuition here :-)

I wouldn't expect the leak to be due to the oil in the system. Instead I would see both as symptoms of the more general problem of things wearing out.

I'm concerned they didn't source a new oil pump - without it, parts of the engine or coolant system may overheat and this could lead to leaks such as the ones you have seen.

I would request a full check of the cooling system, including replacement of any faulty hoses or components, a replacement oil pump, and a repair or replacement of the radiator.

  • 2
    Also you are probably going to have to replace your mechanic. They might be pricey but you get what you pay for.
    – Mike Saull
    Commented Apr 4, 2013 at 15:00

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