Temperature sending unit. 97 960 wagon

rpd960 · Post by **rpd960** » 09 Jul 2007, 13:11

I have 97 960 wagon with a 2.9l six. I believe the temperature
sending unit needs replacing. The temp gauge will go all the way
to hot on occasion then immediatly return to normal, or will vary
from hot to normal at an etremely quick pace (less than a second).

I have purchased a new part but cannot locate it on the motor. I have located the sensor that is next to the thermostat but the dealer says this
is not the one that controls the guage but is for fuel regualtion. The dealer
is no help and will not tell me where it is located but will fix it for me at
a huge cost.

Can anyone tell me where this thing is hidden. It is obvious that it threads
directly into the block and has a 2 conductor fixed connector (no wire).

Thanks

Kmaniac in California USA · Post by **Kmaniac in California USA** » 09 Jul 2007, 15:03

First lesson of working on cars is: Don't buy a replacement part without testing the old one to see if it works correctly.

A temperature gauge that spikes to full hot, then returns to normal quickly, especially within the first few minutes of starting it cold, is a subtle indication of a possible major problem. I had the same thing happen recently to another car of mine (not the Volvo). Turns out I had cracked exhaust valve seats. The cracks were allowing the passage of exhaust gases into the cooling system. The gases would collect as a bubble behind the thermostat, causing delayed thermostat operation when cold.

Return the sender unit and buy a Universal Block Tester. Use the tester to check for the presense of exhaust gases in your cooling system before going any farther.

Let us know what you find and what you do.

wojeepster · Post by **wojeepster** » 09 Jul 2007, 15:10

The volvo has a temperature compensation board and when it goes bad you get the faulty temperature readings you describe. ipdusa sold the compensation board and also a jumper and instructions on how to remove board completely it was around $15. I did this on my car and it has worked flawlessly since and now reads actual temperature. It is a known problem with volvos....

rpd960 · Post by **rpd960** » 09 Jul 2007, 15:18

It doesn't act up until the engine has been warm for quite some time.

Also I don't normally buy repair parts until I have checked the old
ones but from my experience it acted as though this was the problem.

wojeepster · Post by **wojeepster** » 11 Jul 2007, 18:09

http://www.volvoforums.com/m_65840/tm.htm