I bought my 1988 240 wagon a/t about 2 months ago and from the start I have had a overheating problem. I have changed the coolant,water pump, hoses, new thermostat, had the radiator cleaned at a radiator shop. No leaks anywhere. I looked at the coolant, that's ok. The engine oil was just changed about a month ago and looks good. No brown chocolate, foamy stuff anywhere. I flushed the tranny fluid last weekend too. ---->>>>The needle stayed on the 9 oclock mark for this whole month until yesterday. coming off the freeway the needle starts going up. I turn on the heater, it goes down. then it depends if the car is moving or not. The needle goes up and down. Could the new thermostat be faulty? Should I buy a New Radiator? Coolant sensor? The car has been running good this whole month. Im getting about 23 MPG combined. Thanks

 

Two thing come to mind. The temp faker/temperature compensation board or the fan clutch. If the temp faker is defective then it will jump all over both high and low. When you said the temperature goes down when you turn on the heater that make me think it may not be temp faker. It's still posable but? Next would be the fan clutch. If the fan clutch is not functioning properly then it's not pulling enough air across the radiator at idle to keep the engine cool.

Hope this helps,

Ron J

 

Typically if the temp goes down when you turn heat on that means the radiator is bad. Do you have an IR temp gun? If not get one for $20 and take the temp while car is hot. Aim it at both sides of radiator, there should be a 20 degree difference form side to side. If temp is same on both sides then radiator is bad. Also aim at nut on thermostat housing and make sure it's at 180-190...if all good most likely have a bad temp compensator board and gauge is not working properly. If a weak fan clutch car will only get hot or over heat while stopped not driving typically. Are you using your A/C? If you use A/C a lot I would suggest an electric fan as well as the manual you the already have. But get a IR temp gun first and test the temp and see where your problem lies...Good Luck!

 

I finally bought a new radiator from IPD last week and so far so good. The needle stays right @ the 9 o'clock mark even with the AC on. We're now hitting temperatures over 110F over here in Phoenix AZ.
Hey VolvoGuy, do you have a link on adding the electric fan?