Hey everyone, So ive searched the forums for this issue and can't find a match to my problem

I have a 87 GT auto and when I drive on a warm day or even on a cool day and push the engine ( which is brand new ) my temp will reach red hot on the gauge. The coolant light doesnt come on but I know im close to turning it on.

Heres what I have found out and tried.

So if I run the car with out a thermostat it takes longer for the engine temp to get red hot. but it still will reach max temp on the gauge if I drive it long enough. When i put a thermostat in, it will reach the max on the temp gauge within 10 mins of driving.

I have checked and I DONT have a head gasket leak. I have burped the cooling system three times. I replaced the fan relay and the fan motor. I even replaced the fan switch. Still gets hot.

When i did my engine swap last year I did take the a/c compressor off the car, I decided I didnt need a/c and I didnt want to get a new one. my question is, will this cause the fan not to kick on?? Could really use some help on this problem, its got my stumped.

Thanks

Do you know if your radiator fan is coming on?

well I read that if I flip the a/c to max a/c and the fan speed to max it should come on. Ive done that and It doesn't, but I didnt know if that was because I dont have a compressor.

[This message has been edited by FieroJosh1993 (edited 05-29-2015).]

The HVAC control head turns on the fan when any A/C position is selected. The absence of the compressor has no bearing on the cooling fan function.
The cooling fan circuit can be checked by grounding the wire for the thermostatic fan switch on the engine. If the grounded wire turns on the fan the relay and fan are good.

so how is the best way to ground it. Key on engine off and the unplug the fan switch and ground it to the negative battery cable??

engine block

oh ok, just ground it to the block. gotcha, will give this a try,

anymore ideas would be great.

Check this first, then we will move on if needed.

quote Originally posted by FieroJosh1993: When i put a thermostat in, it will reach the max on the temp gauge within 10 mins of driving.

While the car's actually moving?

If your gauge is showing the correct temperature (and that's not a given), I suspect your Fiero has cooling system issues... and I'm not referring to your fan not coming on.

While your Fiero is moving (and air is being pushed through the rad), there's no way your engine should be overheating after any length of time of driving.

But yeah, if your car is sitting still, the fan eventually needs to be kicking on.

quote Originally posted by Patrick: While the car's actually moving? If your gauge is showing the correct temperature (and that's not a given), I suspect your Fiero has cooling system issues... and I'm not referring to your fan not coming on. While your Fiero is moving (and air is being pushed through the rad), there's no way your engine should be overheating after any length of time of driving. But yeah, if your car is sitting still, the fan eventually needs to be kicking on.

Ayup, I don't think mine has come on ever no matter how hot it is when driving, ever. But I do live in Maine so that may have something to do with it. First are you sure the temp gauge is right? I grabbed one of my wife's candy thermometers and just lay the probe right on the thermostat housing. unless you know someone with a touch less laser thermometer nearby you can borrow. the candy thermometers are under 5 bucks, the laser ones start around 30 buck to be sure those are the only ways to get a real temp reading.

like some one else said these thing are famous for reading wrong, hell the one in my Burb never goes above like 150 but the thermostat works and I checked the temp of the engine sitting in the yard running and it runs right around 200 or just a little higher ever, I just hauled our horse trailer full of hay today. I hate electrical gauges they are bad, sometimes way off like my burbs. And all it maybe is a bad wire or sensor.

Oh ya and welcome aboard the nut ship, we have to be nuts to want to drive around in 25+ year old cars.

edit to add, if you do use the wife's or moms candy thermometer go get her a new one, lives have been lost for doing less.

Steve

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Detroit iron rules all the rest are just toys.

[This message has been edited by 84fiero123 (edited 05-29-2015).]

ok sorry its taken so long to post back, was in the hospitle with my mom.

So when i ground the fan switch wire to the block the fan does come on. But when Im driving and the temp reaches 235 degrees the fan doesnt kick on. So what is the issue?? Its a new fan switch, replaced it when i did the engine swap.

Thanks guys

Either your new switch is bad, or it is not getting a ground contact through the threads....did you use teflon tape?

also: If you are reading 235* on the temp gauge, it may be way off. 10% error is not unusual.

[This message has been edited by Gall757 (edited 06-16-2015).]

I didnt put tape on the switch but it did have something on the threads. i dont think it was tape, might have been an anti seize, not sure. So what would be the next best step, get a new sensor or try and clean up the current one and see if it was just not getting a good ground??

[This message has been edited by FieroJosh1993 (edited 06-16-2015).]

If the car is overheating while moving you may also have a clogged radiator

whats the best way to tell if the radiator is clogged, without just buying a new one. any tests I can do??

Don't borrow trouble. The next time the car is hot, feel the exit hose on the radiator. If it is cool...lukewarm, it is blocked. Both the inlet and output hoses should feel hot.

As for the switch, I would clean the threads and put it back in. You should be able to ground the wire on the hex part of the switch and prove that the ground contact is working. If it is working, you probably have a new bad switch....not that uncommon these days, sorry to say.

You never answered my question earlier... but if your engine overheats while the car is moving, then installing a manual fan switch is pointless. Find the actual problem!

[This message has been edited by Patrick (edited 06-16-2015).]

Did you check for pinched coolant tubes under the car? Improper jacking can crush those very easily..

oh sorry patrick, the car doesnt over heat when im moving fast, but if I sit at a light for a long time or move like 30mph or under it gets hot.

I checked all under the car and the tubes look fine.

I just got back from the store and felt both radiator hoses. they are both hot. so its not a blocked radiator. i will check the switch to make sure it has a good ground.

[This message has been edited by FieroJosh1993 (edited 06-16-2015).]

quote Originally posted by FieroJosh1993: ...or move like 30mph or under it gets hot.

I dunno, but I suspect there are cooling issues that won't be solved by switching the fan on manually. As long as the car is actually moving forward, the natural flow of air through the rad should be enough to maintain proper cooling.

Have you had the engine scanned to see its actual temperature? Other than the dash temp gauge (which is notorious for being wrong) reading high, what leads you to believe your Fiero is overheating?

quote Originally posted by Patrick: If your gauge is showing the correct temperature (and that's not a given), I suspect your Fiero has cooling system issues... and I'm not referring to your fan not coming on.

[This message has been edited by Patrick (edited 06-16-2015).]

well, the only time was when the coolant light came on. I never have gotten it that hot again, but if the gauge is wrong then how to I get it to a somewhat accurate reading. The only reason I say the car is getting hot is because the gauge maxes out and i just go home cause I dont want to damage the engine.

quote Originally posted by FieroJosh1993: well, the only time was when the coolant light came on.

To tell the truth, I don't know how that light is triggered. It could be a false alarm as well.

You need to find out the actual temperature. With my own Fiero(s), I'd connect my laptop to the ALDL connector and run WinALDL. Or if a scanning device is available, use that.

so I have a scan tool at work that says it works for obd2 and before, I should be able to see the temp of the engine. I will give this a shot tomorrow. Thanks

quote Originally posted by FieroJosh1993: so I have a scan tool at work that says it works for obd2 and before...

Although I was referring to WinALDL in the following post, This applies to using a scanner as well.

[This message has been edited by Patrick (edited 06-16-2015).]

Update,

Ok so ive done a few things since the last post. I check the temp when the gauge says its in the red and the real temp is 245 degrees. I checked the fan switch and the sensor was not making a good ground to the engine. Replaced it and burped the cooling system. So far I have noticed a difference. I still am getting past 235 degrees and the fan still isnt coming on. Not sure why. Also now I have a strong gas smell coming from the engine area but I cant locate a leak.

The GTs have an air dam in front of the radiator to help push the air up in the it. Does your car have the air dam installed? It won't help at a stop light but once moving it will.

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