HELP! Overheating on Streets

[jrnstang]

Hi Guys,

I just bought an 1985 GT and I have noticed it the temperature tends to climb and climb while driving through City traffic (Signals, stop signs). I tried to run the car without a Thermostat and that did not solve or tell me the Thermo. was bad. The hoses and radiator are in good shape. When I run the car on the freeway or free flow traffic, the car runs fine. I am thinking it might be the fan clutch?

Any ideas or recommendations would sure be helpful.

Thank you in advance for your time and advice.

 

[solow5.0]

What I have done with mine is put in a higher flow water pump, 160 degree thermostat, and a heavier duty 3 core radiator. Runs very cool even in 100+ degree heat, and never climbs up even at stop lights.

 

[2000xp8]

A 160 thermostat is too cold, for a few reasons. Such as the heat don't work well in the winter, and the coolant never stays in the radiator long enough to cool off.

Hi flow water pumps do little to nothing to help cooling on regular cars.

A 3 row radiator however should help aid in cooling, and if the fan clutch is really old, it wouldn't hurt to buy a new one (from ford).
Check to see how easy the fan clutch spins when the car is 100% cold.
Then heat up the car until it's nice and hot, shut the car off, and spin it again.
Should be alot more resistance when the car is hot.

You can also observe the shutdown rate of the fan, cold vs hot, by having someone turn the car off while you watch the fan, it should spin less when the car is shut off, hot.

 

[solow5.0]

My heater works just fine in the winter. Has no problems keeping me nice and toasty even when the temps dip below freezing. The water pump may be overkill, but I got tired of the gauge climbing way up, especially at the drag strip.

 

[DocG]

May sound dumb.....but have you flushed it? Maybe some crap built up inside the radiator that you can't see.

If not, the fan would be my next guess based on what you've already checked.

Also, may be possible you have some air in your system. I had nearly a gallon's worth of air trapped in mine causing it to overheat after I did some engine work and put it back together.

 

[Sicarius428]

Fan isn't pulling enough air through the radiator it sounds like. You can get a larger radiator but it will just prolong the overheating. Rule of thumb is if you are overheating at a stop, the fan can't pull enough air through the radiator. If you are overheating at freeway speeds, your radiator can't cool the water down... or you don't have the plastic deflector thing under the radiator support.
Kevin

 

[HISSIN50]

Fan or fan clutch.

 

[5spd GT]

Fan or fan clutch.

Your car is cool at speed, because air is flowing over the radiator. When your car is not at speed (slow or sitting in traffic), no air is flowing over the radiator.

So what is the probable cause? The answer is in bold.

 

[jrnstang]

Overheating

Thanks guys for the great advice, I really appreciate it. It turns out the Fan Clutch is going out. Hardly any tension after running it and getting it hot. Replaced it and will see how it runs.