Van

Are you sure your radiator fans are working? Above 20-30 MPH, the air flow going over the radiator is enough to cool it. But, if you're stationary, you need those fans working at high speed.

Last Lemming

well I see and hear them on at low speed and when they kick on high speed they both sound like they are blowing HARD.
Plus if I rev the engine at idle the temp drops, so its like there is not enough fluid going over the radiator.

Just more info here but here was no trace of any substance behind the water pump area. I would have thought if stop leak was used this area would show build up of some sort, but it was clean.

mel_t_vin

What model/year is your car?

Describe where the needle sits in the temp gauge [near which line] under operation, driving and sitting.

bordin34

This is what my head gasket looked like when it failed.

Last Lemming

My car is an 86 turbo mostly stock with a Lindsey racing 3 inch exhaust with cat and a Vitesse chip.

If I let the car idle and wait the temperature slowly rise it will go up and the fan will turn on when the temperature is 73°C (using an infrared temperature gun) on the top rubber hose going into the radiator. My Thermo switch is a 85°C/ 93°C switch.

So my benchmark is 12° difference using the top of the rubber hose at the radiator and the top of the rubber hose at the water pump. I say 12° because if my Thermo switch turns on at 85°C and the top of that rubber hose is 73°C that is the 12° difference. So the fluid will be 12°C higher than the top of the rubber hose.

I let the car idle tonight for an hour. The Thermo switch kicked the fan on on at 73°C (based on the top of the rubber hose so really it's 85°C for the fluid) and's once the fan kicked on it never shut off nor did the needle drop the temperature, it stayed on the whole time on the low the setting but the temperature never dropped. The highest the temperature went was 77°C on the top rubber hose. The highest that was reached on the lower hose was 61°C going into the water pump. So if we add 12° to each reading we get 89°C and 73°C.

From from the needle perspective the fan kicked on about 2 mm above the first white tick and rose continuously until it was about half a millimeter from the second white tick. Even though it almost hit the second white tick temperature at the top hose never went beyond 77°C and the lower hose never got beyond 61°C. So if we add 12° to each reading we get 89°C for the top hose and 73°C for the bottom hose for what the actual liquid temperature would be. Take into account that this was all from a cool car that was started cold and idled to these temperatures. I did not drive it to reach these temperatures. Ambient temperature in my garage was probably in the mid 50s.

If I just let the car idle from cold the high fans never kick on the temperature never goes beyond the second tick regardless of how long I let it idle and I let it idle for an hour tonight.

However if I drive the car for 30 minutes I get the same readings more or less but the high fans do kick on so it does get a little hotter probably because the car is under boost and the temperatures are much more dramatic.

Using my thermal gun I did notice one thing interesting, the top of the oil filter was 76°C but the side of the oil filter next to the exhaust read 102°C that is 211°F. I'm not sure what the actual liquid temperature of the oil would be but I am sure it would be higher. I do not have an oil filter heatshield could it be possible that the exhaust is heating up the oil causing me to have creeping temperatures at I idle?

Also note that any time I blip the throttle while sitting at idle the temperature drops a millimeter or two on the gauge but if I let it just sit the temperature creeps up to the second white mark. It never goes above but it never goes down either even with the high fans kicked on. Of course that is my main concern. If I drive the car the temperature goes back down to normal and does not creep up.

Things that I know work: the fans work, the radiator is new, the water pump is new, the thermostat is new, the thermal switch his new, my belts are new, and I flushed the system.

Van

Bad ground for the instrument cluster? Blipping the throttle causes a voltage increase from the alternator and causes the temp needle to move? Does the temp needle also move if you step on the brake lights or turn on the headlights?

mel_t_vin

Thanks for taking the time to write that detailed description. How long have you had your car? Has it always operated in this manner?

Based on what you said, I don't think you have an over-heating issue, at all.

Sounds like, relatively, normal operation. First tick on the gauge is 80*C [176*F], second tick is 100*C [212*F], representing the normal operating range of the cooling system. While rubber is not a very good conductor of heat, it's probably in the ballpark. When you get the chance, for nothing but my curiosity, compare the IR temps at your hose locations to the neck at the water pump and the radiator housing near the upper hose nipple.

Why are you running without an oil filter heat shield? The indicated 102*C at the side of your oil filter is due to radiant heat from your headers...not the temp of oil flowing through the system. Regardless, your shield-less set up is definitely heating your oil to "some" extent. I would put that shield back on...

Last Lemming

The thing is when the lights go on the needle jumps up 1 mm however when I blip the throttle it slowly goes back down not instantly. All my tests were done with no lights on.

Last Lemming

I've had the car for about six months and it's always had the needle near the second white tick however whenever the fans have kicked on the needle did slowly drop. Now The needle doesn't seem to drop when the fans kick on. I'm concerned about this because if the needle isn't dropping then then the car isn't cooling off and if it can't cool off the excess heat this will eventually cause damage I would think that once the fans kick on the temperature is supposed to start to drop back down to normal not stay near 100°C. At least that's what the temperature gauge reads however, the top of the hose tells me it's 93°C or close to it at least.

Oh, the car did not come with a heatshield I need to get one for sure.

odonnell

I can almost guarantee you that it's nothing to do with the belt, as long as you're within a reasonable tension setting.

unless you put it on inside out or something

mel_t_vin

A better spot to light up with your IR gun would be the aluminum water neck coming off the front of the head. Check that when you can and let us know what you come across.

But, as Van already rightfully questioned, the wiring in your car is 27 years old. Any resistance, at any connector, along any length of the wire run, at the gauge cluster, or at the gauge itself, will cause [additive] erroneous high/low readings. Happens with oil pressure, electrical charging, and fuel level indications, as well.

I still don't think you have an over-heating issue...

Last Lemming

While I don't disagree with the wiring being old and possibly having issues the fans do kick on at the correct needle location. And while I agree it might be a little off the fact that it still does not go down after the fans come on still concerns me. The fact that the needle slowly goes up as the temp rises and holds at the second white tick and is backed up with consistent IR readings not dropping concerns me. I keep reding on peoples,cars,that have a known working cooling system how when the fan kicks on the needle drops, but mine doesn't.

odonnell

I was re-reading this thread when I noticed this. My car did the same thing!

You can see it around 0:26


At 1:17 I briefly show a ground... cleaning that thoroughly eliminated a lot of needle jumpiness. Later in the video I show how turning on my headlights moved the needle a little bit

I really hate to keep saying this... but I will because it fixed my problem that you see in the video... replace the cap. It's so cheap!

Last Lemming

I will replace my cap. However my needle only jumps like a mm at most. The overall reading is generally correct I believe.

Now off to buy the cap!

Last Lemming

Cap ordered. Mine may be fine but it's a variable that can be crossed off the list for cheap.