Hi: I have a 1995 940. B230F Engine. Non-Turbo. Autoi Trans. 60,000 miles.

The temp gauge on the Instr. Panel seems to read low at times

. The car will be fully warmed up and it will still read cold.

If sometimes I shut the car off the start it again it will read fine

I've checked the coolant level it looks good.

Sometime the heat feels cool even though the I have the level all the way to hot.

Any help would be appreciated.

Thanks...Mr. Tool
--
Mr. Tool

Second vote for the thermostat. If the heat was always hot, I'd say it was the gauge. But if the heat is not warming the car like it should, there is clearly a system problem related to coolant temperature. It sounds as if the gauge is pretty accurate. The sensors for the gauge don't fail that often.

An easy experiment: Replace the thermostat and find out. It could be broken. That would allow it to run at "norml" temp sometimes, and would cause it to run below normal temp other times. Because it was metering only a certain amount of coolant, not adjusting to the different needs of the system.
--
Chris Herbst, near Chicago.

I don't think it's the thermostat, it's too erratic.

It could be a loose or dirty connection in the circuit, but in my case it was the actual sensor in the cylinder head. It's inexpensive but difficult to get at.

If it's the sensor, it will fail compeletely soon, reading stone cold while the car warms up and runs just fine. You can prove it by disconnecting at the sensor and jumpering the wiring with a resistor (100 ohm should do, I think) - if the gauge reads anything, the sensor is the trouble.

Check the 700/900 FAQ for more.

thermostat, either sticking, or seal gone (sounds like sticking) VERY easy to change (and cheap) about £10 ($15)

put a small bore hose into the header tank and as far down the main hose as you can and siphon out the coolant (DONT GET ANY IN YOUR MOUTH VERY POISONOUS) you will get about 1ltr out....

Undo the 2 nuts holding the thermostat housing (where the top hose off the radiator goes into the engine), Undo hose clamp, remove housing (you may have enough play in the hose to just lift it and push it out of the way...) remove old thermostat, scrape any gunk of faces with a plastic or wood scraper (DONT dig into the metal of the block with a metal scraper...), put new ruber gasket ring on new thermostat, pop in place (see FAQ re notes on which way up!), reassemble, refill with coolant you earlier syphoned, run to temp - check for leaks!...then give it a run and check for leaks for a couple of days...

mine was the same, now it gets to temp inside 1-2 miles tops..