heat gauge varies from a quarter to almost half

[jdc4077]

I have a 2002 s60 straight 5cy volvo. The heat gauge varies from a quarter to almost half, more on the quarter mark. I always get heat, and when the gauge shows almost half, it stays there until you shut the engine down. The fluid level in the radiator is full. Also, the on board computer
does not show anything is wrong. Is their anything I should do?

[Georgeandkira]

Hello jdc, Half-way (9 o'clock) is where the needle normally points. When my temperature sensor went out it failed to the low side, erratically. I don't know if you should change the coolant temperature sensor now or wait until the 0116 code appears, as it did in my case. A new sensor cured the code and the needle functioned normally. I sold that V70 within a year. The 0116 code appeared in our Saab too. I changed the sensor immediately. Turns out it was thermostat. Once one goes it really is easier to change both. Since you must deal with lowering the coolant level you might as well take the oportunity to change your coolant too. Do the whole job, kill 3 birds with one stone. BONUS: I've read that our '02s can have their thermostats changed without changing its housing-don't know if that's true. Kira

[mikealder]

Most probably the thermostat sticking open slightly which is over cooling the engine - Just had to do this on my V70 for the same reason! - Mike

[cleaverc]

I had a similar problem on my 2001 V70. In cold weather, the gauge would barely rise off the peg, but in summer months, it would be close to a normal reading. I replaced the thermostat and everything is working correctly. Figured the old thermostat was sticking in the open position.

HTH,

Chris

[jblackburn]

Do the whole job, kill 3 birds with one stone.

+1. Change the thermostat, ECT sensor, and you may as well flush the cooling system at the same time.