Overheating?

faof2 · Post by **faof2** » 10 Jul 2015, 17:53

This is a 1991 240 wagon with 130,000 miles. The temp gauge goes to just below the "red" occasionally and is normally in the hot range just after warming up, regardless of air temperature and conditions. However, I do not see the usual indicators that I associate with overheating in other cars I've had, such as a "hot" smell, upper radiator hose under pressure, steam coming out, etc. This has led me to believe that the gauge(circuit board?) is faulty and that the engine is not really overheating. Recently when a mechanic was looking at my A/C, with no prompting from me, noticed that the fan turned freely with the engine off. He said it should have resistance and not turn freely. He recommended replacing the fan clutch. This made me wonder if the fan is not providing sufficient air flow. At idle, the fan turns and seems to be fast enough. When I speed up the engine, it seems to spin faster. I do not know if it is turning fast enough at freeway speed. I bought a new fan clutch but before replacing the fan clutch, I have the following questions:
- Should the fan turn freely?
- If it turns freely, could that cause the coolant to get too hot?
- Does the fan clutch normally wear out?
- Is there an easy way to properly diagnose this condition? (not sure why the font changed here)
- Is there a place I can easily put a thermometer to check the coolant temperature?
Thanks in advance for any help I might get.

faof2

lummert · Post by **lummert** » 10 Jul 2015, 19:35

Temperature compensation board.

Salomons Driveway · Post by **Salomons Driveway** » 11 Jul 2015, 09:05

Volvos have a hydraulic fan clutch. The fan should turn with only slight resistance. If you push the fan, it will continue to move for part of a revolution before stopping. Sounds like your fan is working correctly. No easy way to check coolant temperature, but one thing to check is the mechanical thermostat. You can put it in a pot of water on the stove and use a candy thermometer to see that it opens at the right point, either 88 or 92 degrees C which is 188.6 or 197.6 F. If your car is actually overheating You might have a bad thermostat or clogged radiator.
Brickboard posts seem to agree with Lummert. Temp compensation board in the dash can go bad and cause incorrect readings. IPD sells instructions and a jumper wire for $9 or you can probably make it yourself. Always start with the cheapest fix.

93Regina · Post by **93Regina** » 11 Jul 2015, 12:33

faof2 wrote:fan clutch

Imho, if fan clutch had not been replaced in last six years, replace it.

lummert · Post by **lummert** » 11 Jul 2015, 19:57

Salomons Driveway wrote:Volvos have a hydraulic fan clutch. The fan should turn with only slight resistance. If you push the fan, it will continue to move for part of a revolution before stopping. Sounds like your fan is working correctly. No easy way to check coolant temperature, but one thing to check is the mechanical thermostat. You can put it in a pot of water on the stove and use a candy thermometer to see that it opens at the right point, either 88 or 92 degrees f. If your car is actually overheating You might have a bad thermostat or clogged radiator.
Brickboard posts seem to agree with Lummert. Temp compensation board in the dash can go bad and cause incorrect readings. IPD sells instructions and a jumper wire for $9 or you can probably make it yourself. Always start with the cheapest fix.

87 or 92 "C".

Salomons Driveway · Post by **Salomons Driveway** » 11 Jul 2015, 20:26

There is a difference between farenheit and Celsius.
Thank you for catching my mistake before it went too far.

c70_lindsay · Post by **c70_lindsay** » 11 Jul 2015, 21:18

Imho, sounds like a thermostat that opens late, because it runs hot after start up till the thermostat opens. I had a dodge van once that was overheating at -35c on startup, my coolant was bad and "gelled" at cold temperature's preventing my thermostat from opening