87 DL- Cooling / Temperture Issue

Harry von Zell · Post by **Harry von Zell** » 14 Dec 2006, 07:24

My project continues.....

My dash temperature indicator shows very low (indicator almost on bottom) engine temperature even though car is warmed-up and has heat.

Periodically, the indicator will rise rapidly, almost to red zone which panics the crap out of me on the highway. It then usually settles above the half way point.

I changed the Thermostat and I still get the unusual low/high indicators.

Any ideas?? Is this a "cooling system" or temp guage issue??

TIA, this is a great site.
H

Post by **billofdurham** » 14 Dec 2006, 11:36

87 DL- Cooling / Temperture Issue

Assume it is a 240?

Have you checked the temperature gauge sensor unit?

Bill.

LaRy · Post by **LaRy** » 14 Dec 2006, 12:38

It sounds like a bad temp.sensor. Remove the sensor and check it by connecting an Ohm-meter. Dip the sensor into boiling water, the value should probably be 67 ohm +/- 11 ohm at boiling temperature. While increasing the temperature in the water, follow the readings, it should constantly go to a lower value.
I say probably, because I don't know what engine you have, but my guess is that Volvo is using the same sensor values in all types of engines. This value is valid for the B23 and B230 engines used in 740, but the same engine was used in the 240-series.

If you wan't to test the gauge meter, connect a 68 ohm resistor instead of the sensor, between ground and the wire. The reading shoud show 75% value, it should move 75% of maximum possible movement.

Harry von Zell · Post by **Harry von Zell** » 14 Dec 2006, 15:02

My gut check is it's the sensor,and will test it as described. The fluctuations of the guage are so wild I get paranoid just watching it!

Post by **billofdurham** » 14 Dec 2006, 16:02

If you don't have access to either an ohm-meter or a 68 ohm resistor remove the sensor from the engine, attach temporary extension leads (one from the tag on the sensor to the cable in the harness and the other from the metal part of the sensor to earth/ground) and suspend the sensor in a container of water which is brought up to boiling point. Check the needle on the gauge rises smoothly as the water is heated. It should finish up somewhere between normal and hot as the water boils.

The boiling point of water in free air is lower than the boiling point reached in the sealed system.

Bill.

wojeepster · Post by **wojeepster** » 08 Jan 2007, 12:27

It is most likely the temperature compensation board. You can remove this board and jumper two leads and it will read real temp. I used two computer jumpers with the backs cut off and a paper clip or you can buy jumper wire for 15$ at ipd usa.com Down load their instructions which are very clear on how to go about this.

wojeepster · Post by **wojeepster** » 10 Jan 2007, 15:16

http://www.ipdusa.com/ProductsCat.aspx? ... RootID=629

Harry von Zell · Post by **Harry von Zell** » 11 Jan 2007, 07:13

Great find jeepster!

I'm buying one! A guy in my office has the same issue with an '85 240.

Ya' guys are the best

Harry