Car's Temp seems to go too High

[billy mild]

On my car I have noticed that while driving it is always at the first white line. Thats fine, but when sitting sometimes at the light the car will get all the way up to almost the red part of the gauge. Then it will go back down. I think the fans kick on then. Is that normal? Do I maybe need a new fan switch or something?

[Techno Duck]

Make sure both the high and low speed fans turn on.

[billy mild]

How do I do that?

[Born2bwild1191]

I believe that's normal - mine stays at the first line while driving, then up to the last white line (maybe a little past it) and the fans kick on and it comes back down. I think as long as it comes back down and doesnt actually overheat you're OK.

[AaronM]

Year and model please.

The later cars will vary between the lower and upper white lines while at a stop (the fans kick in and the temp goes down). Early cars run the same temps but the way the gauge is calibrated it looks like it's getting hotter and the needle will get closer to the red zone.

The temp will not go down with the car stationary unless the fans come on; if the car is sitting still, the only way for the temp to go down is if the fans come on, so if it's coming back down, your fans are definitely coming on.

[Born2bwild1191]

^^ I agree we need the year and model, but since it's in the turbo forum couldn't we assume its a 951, and that all 951's are late model cars? or is there a difference between the early turbo models(86's) and later ones when it comes to the cooling systems?

[dunl]

Originally Posted by AaronM

The temp will not go down with the car stationary unless the fans come on; if the car is sitting still, the only way for the temp to go down is if the fans come on, so if it's coming back down, your fans are definitely coming on.

I hate to hijack a thread, but I wanted to ask about this. Mine seems to run hot all the time, especially stationary, but if I sit at a light and rev the engine a little, the gauge goes down.

Sign that a fan is not working?

[Techno Duck]

While the fans may come on to cool the car down, if the low speed fans are not turning on the temperature spikes higher than normal.

The best way to check this is let the car idle after it has warmed up completely. Depending on some factors (The type of driving and ambient temperature) you should observe the low speed fans on after a few minutes. On my car this happens about 1 needle width above the first white line. Lay the hood back down and wait a little longer and you will more than likely hear the high speed fans turn on also.

Even on the hot and humid days (95+) sitting in traffic i have never seen higher than the 3rd white line. The highest actual temperature ive ever seen coming out of the cylinder head (at the upper radiator hose) was around 208 degrees on my digital gauge.

Do yourself a big favor and clean all the grounding points and a must, check the condition of the wiring going to the temp sender on the top of the block. Clean the spade connectors on both the sender and wiring harness. Also check for cracks in the insulation of the wiring around where it bends.

Stuff like this makes a big difference in what your gauge reads. Hard to see in this picture, but the insulation on mine was cracked in a number of spots and had corrosion that wicked into the strands of copper. I have worked on many of these cars and all of them suffer the same problems. I ended up cutting the old wiring off and soldered on a new section of wiring and connectors.

[billy mild]

Okay I have a 1986 951.

I have cleaned all my grounds. They may need to be cleaned again by the headlights, but other than that they were bright copper last time I cleaned them. Also I don't ever really hear my low speed fans come on. I will check this out after I get my car back together.

[333pg333]

By revving the car a little when hot at the lights etc you are also making the water pump more, hence you see the temps come down. This is an easy way to help.

[AaronM]

Originally Posted by Born2bwild1191

^^ I agree we need the year and model, but since it's in the turbo forum couldn't we assume its a 951, and that all 951's are late model cars? or is there a difference between the early turbo models(86's) and later ones when it comes to the cooling systems?

You're right. It was a brain fart on my part. I was thinking of the NA cars with the pre-'85.5 interiors.

Originally Posted by dunl

I hate to hijack a thread, but I wanted to ask about this. Mine seems to run hot all the time, especially stationary, but if I sit at a light and rev the engine a little, the gauge goes down.

Sign that a fan is not working?

No, that would be a sign of an air bubble or an ineffective water pump. Or something screwy in the temp sensor/gauge wiring.

[AaronM]

Originally Posted by Techno Duck

While the fans may come on to cool the car down, if the low speed fans are not turning on the temperature spikes higher than normal.

It would get hotter faster if the low-speed fan didn't come on, but I can't see why that would make the high-speed fan come on any later (i.e. hotter) than normal.

An easy way to see if the high-speed fan is working is to simply turn on the A/C at idle. The car is wired such that this should trigger the high-speed radiator fan. Obviously that's not a guarantee that the fan's thermoswitch is working, but it will verify the fan itself.

[CPR]

If it doesn't drop after a light 'rev', this is usually indicative of a faulty temp sensor, or more likely the wiring to it.

Check the ground for it that it has not become compromised.

[rjai0972]

What if the temperature goes up when I turn the A/C and the temperature goes up any leads? Most of these signs apply to myself, I rev the engine and the temperature goes back down!

[UncleRay]

For your reference my 87' turbo runs between the two upper white lines. The fans start around the upper white line and well before getting any where near the red. The car has thermostat part number 94410612905 which I believe should be about 180 F and the turbo thermostat is 95110631100 (don't know the temp rating). For my own piece of mind I had the shop check the water temperature with what I'll call a "master" gauge with known accuracy. Connectors, grounds etc were cleaned as has been suggested by the others in this thread. I also replaced the thermo switch that turns on the fans (they were coming on too early). In slow traffic hot weather, the fan comes on and brings down the temperature, shuts off and after a bit comes back on until the car is moving fast enough to push air through the radiator. It took some work but I now have confidence in the gauge and the cooling systems ability to handle the heat.

[rjai0972]

I have a video do you mind looking at it and giving an input?

[UncleRay]

Anything resolved? Post the video here for all to check out.