temp light, 1994 440SE

[liteman]

Hi can anyone help please. My temp light is staying on and the temp guage is at the top always now. I have removed the thermostat, the rad fan comes on ok so assume heat switch is ok, I can see water flowing through top up bottle so assume water is circulating. Any help out there will be appreciated

[billofdurham]

Welcome to Matthew's Volvo Site.

Is the rad fan running all the time and is there any sign of the water overheating apart from the light and the gauge?

I would suspect the engine coolant temperature (ECT) sensor is malfunctioning.

It is easy to check if you have a multimeter or an ohmmeter.

Switch off the ignition.
Disconnect the ECT multiplug.
Relieve the pressure in the cooling system.
Remove the ECT sensor from the engine.
Immerse the ECT sensor in water of which you know the temperature.
Check the resistance over the ECT sensor terminals with the multimeter.
At 0C the resistance should be 5800ohms.
At 20C the resistance should be 2500ohms.
At 80C the resistance should be 330ohms.

Let us know what happens.

Bill.

[liteman]

Hi there

I replaced the temp transmitter on the engine block with a new one (CI-XTT90-INTR52250). This has not sorted the problems out. The fan appears to be behaving as expected/normal, it switches on for while to cool everything down then switches off.

[billofdurham]

Have you flushed the cooling system?

Bill.

[liteman]

Hi Bill

I have not flushed the system. Is there a proper process to follow or is it simply empty from the lowest point and refill?

Mike

[liteman]

Hi Bill

Just flushed out system. Removed drain plug under rad. Let coolant drain.
Fitted hose to top Rad pipe (pipe which connect to topup bottle) and flushed. Refitted drain plug, then removed thermostat housing and flushed. Fitted thermostat housing back on then flushed through so that water poured out from topup bottle.

Fitted pipe back to bottle. Topped up system with water, bled system, started car and light still on when started.

I'm on a 50 mile round trip to do some work tomorrow afternoon, what do recon my chances of making it back home are?

Hope your enjoying your well earned rest

Mike



Theres a red message saying milage required therefore the cars done 80000 miles.

[billofdurham]

Sorry I stopped a little early last night so have just found this. I hope you made it back home, but you did not say if the system was overheating or is it the gauge and light only.

To flush the system properly you should set the heater control to max heat, open the drain cocks or, as I prefer, take off the top and bottom radiator hoses and flush out the engine with a hosepipe until the water runs clear. To flush out the radiator I always take it off, turn it upside down and back flush it, ie put the hose into the stub pipe for the bottom hose and allow the water to run in the wrong direction. You do not need high pressure water to shift a lot of muck.

Replace the radiator, make sure the heat control is still at max and fill the system through the topup bottle, slowly, to avoid air locks. Also whilst filling the system massage the two large radiator hoses to help get rid of any air.

Bill.

[liteman]

Hi Bill

I made the journey ok, got to do it today again, good test I suppose. I flushed the system out well in many directions so any debris must have moved. It is the gauge and light only which is causing the problem.

Thanks

Mike

[billofdurham]

So the little electric gremlins are at play.

As there is no sign of overheating and you have replaced the temp sensor I would think that you have a short circuit to earth (ground) between the sensor and the gauge/light.

Check the wires very carefully for chafing or broken insulation, especially in the engine compartment where heat can play havoc with wiring.

Bill.

[liteman]

Hi Bill

Checked what wiring I could visually see. Harenesses dissapear which makes following them not possible.

All wireing in engine bay appear good and insultated.

I have checked fuses, removed fuse panel to check wireing behing this and again all appears ok.

I removed the instrument panel (relative easy process) solved one issue of the light (removed bulb), but unable to work out where to and from the analoge guage wiring is, so I could put in a temp wire to bypass original wire loom as a test.

I would have thought the wiring was from the temp sensor to the guage, but not sure.

If its not this then the guage itself would be suspect? but this does not explain the light comming on on the instrument panel.

What do you think?