rob1271

help my S4 is overheating when in traffic or asending hills, I can hear the fan going on, but for only for a seconds at a time. On the open highway it stays cooler but runs hotter than normal, almost to second white line. helps when air conditioning is on. any thoughts

Giovanni

Did the 87 have the cooling flaps? Make sure they are not stuck on the close position.

Mongo

Mine did exactly what you're talking about. The next time your car is shut off, run outside to check if the cooling flaps are open. If they are, pull the fuse to the cooling flaps under the passenger floor board of your car. This will keep your car cool in stop and go traffic.

killav

For what its worth, my 87 S4 runs at the first white line (1/4) when moving down the highway. If I enable the cooling flaps (I live in Texas and pulled the fuse), it will run slightly hotter (in between 1/4 and 1/2) with the flap fuse in and moving down the highway. In spirited driving with flaps disabled, it will run at 1/2 or just above. In stop and go traffic, with a/c on, after spirited driving, it will hover at 3/4 but no higher. The third white line might seem like your car is over-heating, but as far as I know, this is still in the "normal" operating range of the water temp. All the above temps are in the dead of summer-100 degree days plus.

It does sound like you have something going on. Especially since you are having this problem when the temps (depending on where you are) are not 100 degrees. Give the flaps a try first. My fan operates much longer than a few seconds once they come on. They usually don't even turn on until the engine is at the middle white line.

fabric

Your car has 2 fans. Are they both going on? If only one is running, it will definitely get hot when in stop and go. Easy first place to check is the fuse for the fans, they each have their own. If only one is running and the fuses are ok, a quick search will let you know where to start, this issue has been known to occur before.

jon928se

With the ignition off and the engine cold (to make sure the fans don't start automatically and remover your fingers) try to spin each fan around with your finger, if they don't spin and the resistance to turning them is "lumpy" it is likely the bearings in the fan motors are U/S. This can cause sufficient resistance for the thermal protection circuit in the fan controller to cut in stopping the fan without blowing the fuse.

If one fan works and the other doesn't but both are smooth spinning by hand swap the electrical connectors to the motors and see if the other fan now works.

You can test the fans with a cold engine by switching on the AC, temp set at minimum, heater fan on at least position 1 and set to the vents position - both cooling fans should spin at full speed and flaps should open fully. If your AC has no gas pressure (which will stop the AC controller from switching the cooling fans on) bridge the contacts on the top pressure switch - on the top of the cylindrical pressure switch housing mounted on the side of the larger cylindrical AC reciever dryer. This won't switch the AC compressor on - that is controlled by the pressure switch on the bottom of the pressure switch housing.

heinrich

How is the thermostat and how are its seals front and rear?
Check the temp sensors. In the radiator and on top of the engine.
How is the coolant mix vs distilled water? Too thick?
Your car should run at the middle when normal, at the top white line when hot.

jetrainor

I've got heating issues with my 87 (88 motor)...i've pulled the flap fuse, so its wide open, new thermostat and both gasgets, fans work fine......but what happens is it runs at normal temp then the needle climbs to the red line then will instantly drop and just kind of do this off and on. I put new temp sensor on the engine and repaired a leaky radiator tank, but wasn't aware Heinrich that there is a temp sensor in the radiator. Its probably HVAC related because my heater fan suddenly comes on and blows hard then shuts off, no matter what the controls are set at. If it makes a difference, i pulled the AC compressor out when i swapped motors as well as the air pump.....don't mean to hijack the thread but there may be similarities.