AFAIK the OM606NA engine uses an oil-to-coolant oil cooler. There are coolant lines leading down to the oil pan on the exhaust side. The coolant lines connect to a heat exchanger that is part of the oil pan. Oil from the oil pan is sent by the oil pump through the heat exchanger and then up to the oil filter and on to the engine.





Although Mercedes must have given serious thought to the risks involved in such a cooling system, they must also have built the thing so that leakage would be extremely unlikely. Nevertheless, I would advise disassembling and inspecting this cooler. Among other things, it may be easier than pulling the head again.

You might investigate whether it is possible to block the flow of coolant into the heat exchanger temporarily; if the engine is not run hard in hot weather an oil cooler should not be necessary. That will allow you to determine whether oil is still getting into the coolant. With the coolant lines disconnected, oil might leak out of the connections, another good indication that the cooler has a leak.

Jeremy

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"Buster" in the '95

Our all-Diesel family
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