Hi I have a 1985 245ti with a overheating problem that is getting worse by the minute. The expansion tank is empty every three week, and I fill it up every time it gets low. It doesn't leak the coolant and one of the cylinders is not compressing. I was thinking that it's the head gasket, but I don't want to embark on this quest for nothing. I want to make sure it's the right thing. Today I was driving up a small hill for about a mile with the heater on full blast and the car got up to 3/4 of the way on the temp guage. I was wondering if it could be a stuck thermostat or bad radiator. I don't think it's the thermostat becasue it stays closed until the engine warms up. Should I mess with having the old junky radiator cleaned out or should I get a new tripple row heavy duty radiator for $119 shipped from eeuroparts.com? I live in the desert so is it worth it to just go ahead and get the tripple row anyways? What should I do with the head gasket and the radiator? HELP!!!!!:(

Charles 1985 245ti 134K :(

If the head gasket is bad, coolant could be getting into your oil. This can damage your engine. Check your oil right away. It should be somewhat clear even if it has darkened from mileage. It should not be milky, opaque, foamy, or have moisture dropplets. Any of these indicate coolant contamination. Along with the low compression, that means the head gasket is bad...odd for such a low mileage car.

If the oil is nasty looking change it then replace the head gasket.

BTW: Thermostats typically fail in the open position. If the thrmostat were to fail shut the top radiator hose would not be hot when the engine is up to temp.

mormit
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85 245DL, 02 S40

The coolant loss and low compression are rather strong clues.

A good shop can test the gas above the coolant to detect carbon monoxide, which would enter the cooling system through a leaky head gasket.

Unfortunately, it's a "one way" test. That is, the presence of CO means a leak, but the absence of CO doesn't always mean that the head gasket's not leaking.

You might also have other problems, such as a crummy t-stat or a partially plugged radiator. Try blasting the (outside of the) radiator with strong stream from a garden hose -- the fan side toward the gril. This might blow out leaves, pine needles, grime, grunge, candy wrappers, etc., that block the air flow.

I wouldn't install a radiator 'til you answer the head gasket question.

Keep in mind that you might need to have the head machined, and in a worse-case scenario, you might need a replacement head. Answer the expensive questions before you sink money into the small stuff.
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Don Foster (near Cape Cod, MA)