Please please help me.I have an 1987 240 glt with 198000 on the clock.I noticed last week that the engine temp sat at the beginning of the red and moved back down when i went down the motorway.I checked the engine and steam was no where to be seen and the engine seemed ok.I assumed a stuck shut thermostat so replaced with an aftermarket one,no joy!I removed the stat and the temp sat at the nearly cold mark. Assumption was a dodgy aftermarket stat so tested both the old original volvo one and also the new one.Both stats seemed to operate fine in the boiling water test.As a matter of course i have replaced the noisy pump and a new radiator was fitted.The old one rotten where it sits in the bottom brackets.I flushed the block back and too and the water was clear as daylight.I have also fitted a new sender and checked that it had 10 volts at the sender connection.I checked for a'temperature compensation board'there isn't one!I have changed the gauges(both temp and fuel)in case of a back feeding problem. The pcb also swapped to no avail.I have also today changed the thermostat(again)for a proper volvo one at 87 degrees opening.This problem is still there!I managed to get another voltage regulator even though i had a nice 10v at the sender.There is no bubbling in the expansion tank and the car seems to run good on 95 octane.This problem is driving me mad and i now rather dislike this car at the moment!please anyone any ideas?john

The car has two temp sensors, one for the guage and one for the LH fuel control unit (if your car is LH instead of k-jet). I would measure the resistance of the LH sensor and compare it to the attached chart to see if its really over-heating or not. It should be ECU connection #2.

The system also needs to be pressurized by the coolant tank cap.

Thanks for the reply robert.My system is the old fuel injection type.I did block the cap temporarily with a piece of thick plastic bag to see if it was letting pressure out.When i undid the cap with this temporary measure in place ,no hiss was apparent.I am told that the 240's run with little pressure.I tried pressurising the header(expansion tank) with a compressor and the cap did hiss with some psi in it.This confirming the tank would pressurise.It doesn't seem to be pressurising much with running though!I am thinking possible head gasket, not showing symptoms through the expansion tank though.regards john

problem now solved!After testing the new sender,i had found that the characteristics of resistance against temperature where incorrect.This meant that at normal running temperature,there was too little resistance.This allows the gauge to registar more,ie ghost high temperature.I tested the coolant with a k type thermocouple connected to my multimeter and also an infrared gun.This showed that the engine was happy.Also i was able to use volvo's test resistor which shows up half way on the gauge if the gauge is well.This was thanks to graham wrightson of oxton who has a volvo garage,many thanks graham.So after all this it was back to rybrook volvo of chester to buy a volvo sender,at 3 times the cost of the aftermarket one.When this was fitted the gauge sits at 9 o'clock.JOY!!!moral of the story is always buy overpriced volvo gear,it may just save you ball ache.Strangeley enough, both the new volvo item and aftermarket item registered the same 1000 ohms at ambient.It is the characteristic that counts.cheers all hope this saves someone some grief and agro!john

nice post JJOVLOV! Nice detail.

Thanks for that,she's behaving like she should again!Just this week got another years mot on the glt (IMG:style_emoticons/default/amen.gif)