Car Running Hot

[plantmeister]

Hello all,

I have recently installed a 3-well performance radiator, replaced all heater hoses/radiator hoses, heater core, and put in a new 190 F thermostat in. I know stock for the 1988 is 195, but I figured a 190 would be better.
However, the car continues to run hot, hovering around 210 or 220. When it sits in stop and go traffic, the temperature steadily rises and will not drop down until I start driving again and it has air flow.
I assumed a radiator that huge would have helped, but it doesn't seem to want to stay the right temperature. Since the repairs, there are no more coolant leaks, so I'm at a loss of where to look next.
I heard it could possibly be a fan clutch? Or could my thermostat be bad?

 

[Dan02gt]

The clutch fan would be my guess. They go bad after a while and don't put air through the radiator like they should.

 

[FourEyed]

Yep..fan clutch.

 

[wgreenlee4]

Yeah that does sound like fan clutch but I wouldn't just throw parts at it. I believe you can use a brush or something while the car is running and if you can stop the fan then the clutch is too weak. Also the shroud should still be there.

 

[Fordfreak93]

When you replaced everything did you happen to replace your radiator cap? The cap is an essential piece of the puzzle that keeps the system pressurized, which actually raises the boiling point of your coolant. If you haven't replaced your cap in the last few years, it might not hurt to try a new one. If your cap has a release valve on the top, you can carefully check it while hot to see if it is under pressure. I would also make sure you burped all of the air out of your system. That can cause cooling nightmares too.

 

[plantmeister]

When you replaced everything did you happen to replace your radiator cap? The cap is an essential piece of the puzzle that keeps the system pressurized, which actually raises the boiling point of your coolant. If you haven't replaced your cap in the last few years, it might not hurt to try a new one. If your cap has a release valve on the top, you can carefully check it while hot to see if it is under pressure. I would also make sure you burped all of the air out of your system. That can cause cooling nightmares too.

I did have a problem at one point with a bubble making the system read in the red the entire time I drove it, but I got the bubble out and it dropped, but still loves to stay above normal.
I bought an SVE radiator, so it came with a brand new high pressure cap, so hopefully that isn't my issue

 

[Mustang5L5]

With the engine off, grab the fan and spin it. Does it freewheel loosely, or does it have resistance and move stuffky

 

[plantmeister]

With the engine off, grab the fan and spin it. Does it freewheel loosely, or does it have resistance and move stuffky

I spun it and it seems to have a bit of resistance to it; it makes about 1/4 travel.
I did start the car and turn the AC on and the fan speed didn't change; I was told it was supposed to speed up.

 

[General karthief]

Fan clutch sounds good at 1/4 turn, no it does not 'speed up' if you turn the air on, stock belt driven clutch fan.
Get another thermostat, same temp and test it by putting it in a pan of water on the stove with a meat thermometer and make sure it opens at the right temp, make sure you have good flow through the radiator.

 

[Dan02gt]

As odd as it may sound clutch fans can and should speed up. This is based on the slip percentage vs the temp.

I ran this Flex-a-lite : Amazon product ASIN B000FK9OWKView: https://www.amazon.com/gp/product/B000FK9OWK/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1


notice in the specs it runs at 30% of water pump speed at temps under 160 and 70% of water pump speed at temps over 180.

My stock clutch fan seemed fine to going by the spin test and the car didn't get hot in cool weather, but turn the AC on a the heat would start to creep up at idle. I replaced it with the unit I linked above and now it stays rock steady. Seems my old factory clutch was just slipping to much.

 

[General karthief]

Yea, I should have retracted that, I realized I was wrong when I was driving my truck last night and could hear the clutch fan while driving.
It's the boob thing again.

 

[plantmeister]

Alright, I replaced the fan clutch, and the temperature appears to hold steady at idle, but when I start driving, the temp rises and stays at a certain point. I come to a stop light, and it drops a bit.
I talked to the previous owner and he did replace the water pump.
Could my new, bigger radiator be a problem? Could there be a problem with the thermostat? It seemed to be okay before I replaced these things.
I don't understand why it's still running hotter than it should. Here's where the temp normally dances around.

 

[5.0specialist]

Check the radiator cap. When I was running really hot for no reason, the ford racing radiator cap was not allowing the system to properly use the overflow tank properly since it would not seat properly. I put back the stock radiator cap and all of my over heating problems went away. Also, are you using 100 percent coolant?

 

[plantmeister]

Check the radiator cap. When I was running really hot for no reason, the ford racing radiator cap was not allowing the system to properly use the overflow tank properly since it would not seat properly. I put back the stock radiator cap and all of my over heating problems went away. Also, are you using 100 percent coolant?

When I got the radiator, it came with a high pressure cap that was extremely difficult to get on. I've taken it on and off a few times, but it seemed to be seated fine.

Here's the deal with the coolant. When the guy installed the radiator, I gave him two bottles of straight coolant and two bottles of distilled water, and warned him ahead of time that the coolant needed to be diluted from full strength.
When I came back out, he had dumped the 2 full jugs of straight coolant in, and only half a gallon of distilled water. So I'd say it's running pretty much straight coolant

 

[5.0specialist]

When I got the radiator, it came with a high pressure cap that was extremely difficult to get on. I've taken it on and off a few times, but it seemed to be seated fine.

Here's the deal with the coolant. When the guy installed the radiator, I gave him two bottles of straight coolant and two bottles of distilled water, and warned him ahead of time that the coolant needed to be diluted from full strength.
When I came back out, he had dumped the 2 full jugs of straight coolant in, and only half a gallon of distilled water. So I'd say it's running pretty much straight coolant

I ran 100 percent coolant in my old 93 and it would always run on the hot side like yours, even with a new radiator and fan clutch. I drained out 60 percent of the coolant and filled the rest the way with water and it ran cooler afterwards. My ford racing radiator cap in my 91' was also snug and it seemed like it fit properly, but the valve was not allowing the radiator to utilize the overflow tank. It would go all the way up to the O in NORMAL and when I got home, the over flow tank was very full. Overall, for warm places like Florida, I suggest a 70% water 30% coolant mix. Pure water is bad, cause it causes the metals in your system to oxidize. If you live up north, then use a 50/50 mix.

 

[General karthief]

I will add:
Do not use well water to mix with your antifreeze, you should use distilled water but I've used tap (city) water for years with no issues.
Carry on.

 

[5.0specialist]

I will add:
Do not use well water to mix with your antifreeze, you should use distilled water but I've used tap (city) water for years with no issues.
Carry on.

I agree. I used city water with no issues as well.

 

[plantmeister]

Alright, drained the coolant out and re added. Now it's diluted a little more than 50/50.
Started it and revved it for a little bit until the fluid in the radiator started going up and down, closed it up and watched. Temperature went up to halfway between the half and 3/4 mark (220-230 F) and stayed there.

Now, when I had the stock radiator and stock thermostat in, it ran and stayed cool just fine. Now with aftermarket and performance parts, it seemed to start this, by coincidence I don't know. It was also around the time the heater core went out, which has since then been replaced. I'm baffled.

 

[mikestang63]

if the car is overheating at idle it is a fan or water pump or thermostat issue
if overheating at speed then it is an airflow issue- radiator clogged, not adequate, cracked, etc. Air damn missing or it is an issue with a collapsed hose,

have you burped all of the air out

 

[5.0specialist]

Alright, drained the coolant out and re added. Now it's diluted a little more than 50/50.
Started it and revved it for a little bit until the fluid in the radiator started going up and down, closed it up and watched. Temperature went up to halfway between the half and 3/4 mark (220-230 F) and stayed there.

Now, when I had the stock radiator and stock thermostat in, it ran and stayed cool just fine. Now with aftermarket and performance parts, it seemed to start this, by coincidence I don't know. It was also around the time the heater core went out, which has since then been replaced. I'm baffled.

Try reinstalling the stock thermostat, to see if there is an issue with the replacement. If it still runs hot, then it is probably the aftermarket radiator. I'm running a stock 2 row copper radiator with a 180 degree thermostat and heavy duty fan clutch (the ones recommend for mustangs with a/c) and it stays around the A most of the time.