88 Volvo 240DL Intermittent overheating mostly on trips Topic is solved

DER · Post by **DER** » 22 Sep 2005, 14:25

Temp gauge will almost redline one time and the next time shows oK.
some history: Purchased new 11/31/87
6/21/88 Volvo Dealer replaced temp compensator
2/24/89 Volvo Dealer said temp control adjustment was loose
1/16/90 Volvo Dealer found a loose hose
10/26/90 Volvo Dealer replaced compensator and voltage stabilizer
12/31/90 Volvo Dealer replaced compensator and voltage stabilizer
The above shows the dealer's attempts. After 30,000 miles I quit going to the Volvo Dealer. Other maintenance and service work has has been done by others. One mechanic said this was characteristic of the pre 90s Volvos and I may need to put on an aftermarket fan to help it cool on trips.

The coolent and thermostat has been replaced on a regular basis and the radiator flushed. No leakage of coolent has ever been detected. The fan appears to be working. None of the mechanics have indicated a fan problem when I've had it serviced. One person said I should hear the fan kick in when the thermostat began to read hot. I never have heard it. I have checked when it was running hot and the fan is pushing air and the hose while hot, can be squeezed. It tends to run hot when taking long trips in the hot summer down south in the US., traveling in +95 %, in large cities like Atlanta, GA., and in bumper to bumper traffic where you have to slow down to less than 10 mph. Although it has run hot while traveling on the interstate.

I checked the last two thermostats by placing them in hot water to be sure they were opening properly. I have replaced the heat sensor. I had a mechanic check the connections behind the odometer panel and the compensator on my last trip and they checked out oK. The car still almost redlined two time returning home on the 500 mile trip. Each time it was under the conditions mentioned above. Another thing I need to mention is that when the thermostat reaches the redline, I always turn off the air condition and turn on the heater and the thermostat gradully returns to normal. What could the problem be? HELP
Thanks in advance[/b]

Guest · Post by **Guest** » 23 Sep 2005, 22:02

I have had similar things on my 87 240. First time it happened realy worried me but it returned to normal before i could find a place to stop. Subsequent times iI have stopped and checked the engine area only to find the coolant was at normal temp with no boil over or extreme heat. was even able to open the cap (slowly ) and the temp still read high. Dont know why it does it!?

Science · Post by **Science** » 27 Sep 2005, 14:26

Possible but not sure -

The radiator gets clogged externally with bugs and sand. That restricts air flow enough to make it get hot sitting with the a/c on. You can take the radiator out and wash it out with a garden hose. Just keep flushing the debris out by rinsing the radiator in both directions. This has fixed a BUNCH of 240s with this exact symptom. I have taken temp readings at the inlet and outlet and have found as little as a 5 degree(F) difference in water temps. A new radiator will have a difference of around 50 degrees.

Guest · Post by **Guest** » 12 Oct 2005, 17:41

You can bypass the temperature compensation board. I did this on my 1988 after years of sometimes normal sometimes weird temperature faults. I went to ipdusa.com and downloaded their instructions for bypassing the temperature compensation board. I used two computer jumpers with the backs cut off and my own small wilre. My temperature always reads correctly now. If I had known how to do it I would have done it years earlier. I was too cheap to pay them $15 for a piece of wire.

Guest · Post by **Guest** » 12 Oct 2005, 18:09

http://ipdusa.com/productscat.aspx?Cate ... RootID=629