My 1987 300TDT overheats while climbging long hills. After reading various threads on this forum, I am beginning to wonder if there is some sort of head crack problem even though there are no symptoms.

There is no oil in the cooling system, and no water in the oil. The radiator is brand new. The upper radiator hose doesn't seem to be pressurized when the engine is cold as descibed on several threads. The engine temp. stays slightly over 80 degrees C while driving around town on flat roads, but when I drive up a long hill (over 1 mile at 6% grade) with the ambient temperature around 80 degrees F the engine temperature shoots up over 100 degrees C. It then becomes necessary to turn the defroster on to keep the engine temperature below 100 degreees C.

The mechanic I have looking at the problem hasn't found any hydrocarbons in the coolant yet, but he is planning on running some more tests tomorrow.

Does anyone have any ideas as to what might be causing the engine to overheat on hills?

Thanks in advance.

-Steve

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1987 300TDT smoke silver w/ burgundy leather interior
2000 VW Passat wagon indigo blue w/ beige leather interior
1985 Mustang SVO
1970 Chevrolet K10 fleetside, shortbed