skystrick

'86 Coupe GT

Radiator cooling fan doesn't come on. Car overheats when idling.

Both temp gauges read low (the main coolant temp gauge on the dash, and the little round oil temp gauge above the shifter.) The needles move MAYBE 1/4" above the lowest mark when everything is heated up.

Seems weird to be a coincidence?

AudiCoupeGT1986

I'm thinking you have a few issues with your cooling system.

I think first step would be to replace the thermostat. It could be sticking hence the overheating and other problems. Best to do a full coolant flush and replace with fresh coolant.

I would also consider replacing the Coolant Temp Sensor and Coolant Temp Sender which are both located on a flange going into the head. Also, while you are replacing those, check the wiring for each to make sure they are still in good order.

skystrick

Thanks for the reply, @AudiCoupeGT1986.

(1) Where is the oil temp sensor located?

(2) As a worse-case scenario, is there any reason I can't wire the radiator fan directly to the battery, with an on/off switch inside the car?

AudiCoupeGT1986

Np!

If my memory serves me correct, it should be the sensor on the bottom side of the coolant flange. The coolant temp sender is the one on the top end of the flange. I'd replace both with if I was you. Check the wiring for them as well as shoddy wiring can also cause issues.

I suppose you could just directly route the fan to the battery with a switch but I would personally try to find the root cause. Do it right the first time.