Car Overheating: Not Thermostat

topless98gt

Adhesive Feces
Mar 31, 2005
182
0
17
Arlington, TX
My car started overheating just as soon as the temperatures started hitting near the triple digits.

I've had a problem in the past with: leaking heater core (~1.5 years ago), busted PCM (~7 months ago), bad thermostat (~2 years ago), coolant temperature sensor (~2 years ago).

I boiled my thermostat and it opens just fine. I have yet to test if it overheats with the vents turned to max heat. I tried to idle it to the point of overheating the other day, and the fan kicked on; the A/C even blew cold. However, if I idle after driving for a bit, the fan does not seem to kick on, even with the A/C.

1) How can I diagnose as the water pump?
2) How can I diagnose as the fan and/or fan relays?
3) Is there an easy way to make sure the head gasket is not bad (and letting exhaust fumes leak into the coolant, thus making it much hotter)?
4) My car has two temperature sensors, one for the fan, and one for the gauge. How do I test these?

Any advice is much appreciated. If you need any further information, please ask.

Thanks in advance!
 
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If you have a handheld tuner - set your fan temp to 160 degrees. I live in Jacksonville, FL, temp is triple digits and humidity is almost always near 100% this time of year. I drive my car HARD in the heat and have never even seen the temp gauge budge past the normal halfway mark. Might be a stupid question, but when is the last time you changed your oil? And what oil are you using?
 
I would first get the fan working. Pull it out and put 12 volts to it and see if it works like that. If it does, then you know your problem is else where. Check all your grounds and fuses.

Have you looked into replacing the radiator? The cooling fins could be plugged. I would also replace the water pump while you are there. They are about 45 bucks and easy to replace.
 
If The CCRM is over heating or going bad it will prevent your fan from kicking on. If it doesn't turn on when the A/C is on try a 12volt source to it to see if the fan works. If it does come on with a 12v source then it could be the CCRM.
 
I would first get the fan working. Pull it out and put 12 volts to it and see if it works like that. If it does, then you know your problem is else where. Check all your grounds and fuses.

Have you looked into replacing the radiator? The cooling fins could be plugged. I would also replace the water pump while you are there. They are about 45 bucks and easy to replace.

I listen to this dude about getting water pump at autozone, and it work great.
 
Might be a stupid question, but when is the last time you changed your oil? And what oil are you using?
March 15, 2008. I don't drive it that much, so I go based on time period. I'm changing it this week as soon as I can make it to the store to pickup the supplies.

Do you have the plastic intake manifold?
No idea. How do I check? When I bought the car, the owner said he had replaced it, but it still looks plastic to me. Somewhere I heard that it's just the NECK of the intake manifold that's aluminum. Is this true?

When you had all those problems I hope you didnt ever add any "stop leak".
That stuff will block coolant passages and wont come out just by flushing
the system.
I did...that was when my heater core was acting up... :bang:

If The CCRM is over heating or going bad it will prevent your fan from kicking on. If it doesn't turn on when the A/C is on try a 12volt source to it to see if the fan works. If it does come on with a 12v source then it could be the CCRM.
The CCRM is the Constant Control Relay Module, correct? If so, then that is what I had replaced back about 7 months ago. There are so many different names for that module it's not even funny. I'll test the fan.

I listen to this dude about getting water pump at autozone, and it work great.
I don't mind replacing parts, it's fun. The car is 11 years old, it could use ALL new parts. I just don't wanna waste my time replacing them if it's not going to help for the future. I'll check into getting a new Fluidyne radiator and a water pump from the auto parts store.

Dale,

I was having the same problem, replaced my water pump and the car never gets past the "R" (the dummy gauge) in Normal
Thanks Justin. How difficult is the water pump to replace? What is involved?
 
Drain all the fluid from the bottom petcock on the radiator tank. Pull the overflow bottle out of your way. Then pull the belt off, and the water pump pulley off. There are just a few bolts holding it to the block. After the bolts are out, gently tap it with a rubber mallet. It will come right out. Clean the area. Install new pump and all other parts in reverse order. The new pump won't come with a gasket because there isn't one. It is an O-ring that comes with the pump.

I had some minor minor discoloration and corrosion on the water pump impeller. It also wasn't as tight as the new one. Nothing to worry about, but I feel good having new parts in place of 79,000 mile old parts.
 
The only part that was redesigned by Ford was the "crossover" (where the thermostat housing sits). If that part isn't plastic, then it has been replaced. The intakes are prone to cracking/leaking at that crossover...
 
My car started overheating just as soon as the temperatures started hitting near the triple digits.

I've had a problem in the past with: leaking heater core (~1.5 years ago), busted PCM (~7 months ago), bad thermostat (~2 years ago), coolant temperature sensor (~2 years ago).

I boiled my thermostat and it opens just fine. I have yet to test if it overheats with the vents turned to max heat. I tried to idle it to the point of overheating the other day, and the fan kicked on; the A/C even blew cold. However, if I idle after driving for a bit, the fan does not seem to kick on, even with the A/C.

1) How can I diagnose as the water pump?
2) How can I diagnose as the fan and/or fan relays?
3) Is there an easy way to make sure the head gasket is not bad (and letting exhaust fumes leak into the coolant, thus making it much hotter)?
4) My car has two temperature sensors, one for the fan, and one for the gauge. How do I test these?

Any advice is much appreciated. If you need any further information, please ask.

Thanks in advance!

Lot's of great advice in the replies.
My take on it....

If you are not losing coolant (not when it overheats, but normally)
If the fan comes on normally and especially with A/C on.

You have a clog somewhere.

Radiator is first culprit on a car that old.
Using the stop leak didn't help, we all learn that one.
Water pumps on American cars usually either work or don't work and when they start to fail they weep fluid or make noise.
Foreign cars, especially VW/Audi/Porsche are different in that they use cheap ass plastic impellers pressed on to knurled shafts and the impeller tends to loosen up and slip causing poor fluid movement.

The one exception is an impeller that has rusted away and the blades are no longer there.
I *have* seen that one, but it is pretty rare.


If you don't want to shotgun parts replacement, try some Prestone Flush and double the time they tell you to leave it in the motor.

I'll be honest, it probably won't help but it's worth a try as a last ditch effort.

I would start looking at either a radiator or heater core if I were you.

I haven't been in that area yet on my stang, but some cars allow you bypass the heater core by connecting the inlet and outlet together with a piece of copper pipe in between. Also some cars (not sure about Ford) have the heater core in the loop all the time and only the flapper in the A/C box determines whether the car gets heat inside or not.

If this is all true, try bypassing the heater core and see if it helps.

One last thing, replace the thermostat anyway even if the boil test works. I've seen many a t-stat that only failed when it was torqued down in the housing but worked perfectly during the boil test. The slightest bend or manufacturing defect will cause it to not open under stress.
 
One last thing, replace the thermostat anyway even if the boil test works. I've seen many a t-stat that only failed when it was torqued down in the housing but worked perfectly during the boil test. The slightest bend or manufacturing defect will cause it to not open under stress.

+ billion

try this before you spend too much money - remember when we boiled my tstat and put it back in the car but the car kept overheating? we pulled over at vato-zone and replaced it in the parking lot and never had another problem? :hail2:
 
Has the fan ever been replaced?

You can test the fans low speed and high speed function from the CCRM by running the car and letting it get to operating temperature. The fan should kick on once the car gets to the high side of normal. Turn on the AC, disconnect the fan electrical connector (use gloves, that upper coolant hose doesn't live up to it's name :D ) and using a voltmeter probe the black (ground) and the red/orange (low speed) wire to check voltage. If you have voltage, and you should if the fan is running, then move the red probe to the orange/light blue wire and see if it has voltage. May take a minute for you to get a reading...just wiggle the probe around a little. If you do then the CCRM is functioning properly.

My problem was similar to yours but 3 issues in succession caused my problems. 1st I was overheating only in hot weather and only with the AC running (see reason I feel it was running hot in 3rd item below) Then it started over heating badly one day and I discovered the fan wasn't running. The fan had seized. Could be an issue with yours if it is beginning to go bad.

I replaced it and didn't have an issue until the female connector wiring on the new fan came loose. Thought it was the CCRM and replaced it then I discovered the faulty connector after wiggling it around. Replaced the fan under the lifetime warrenty and haven't had an issue since. So check the harness and make sure it hasn't worked it's way lose.

The third item here was discovered after replacing the original fan. Since I had owned the car it always ran up in temp range (between the A and L of normal). When I replaced the fan it now runs cooler, MUCH cooler. Around the O and R of normal. A little research and I think the stock fan was of an inferior design. The new one does much better in keeping the engine cool.
 
I have never replaced the fan. I've owned the car since Dec 7, 2004.

What's a good brand of fan to go with? The fan connector has melted in the past, and when I had the CCRM replaced, they put silicone sealant on the connector to keep it in place. This means that I am unable to easily disconnect the fan.

I really don't see how it could be the CCRM since it was replaced just about 7 months ago. But who knows.

Note: I have been driving the car with the heater blasting, and it has not overheated once, not even close.
 
I'd replace the thermostat 1st, then flush and fill and BE SURE you don't have air trapped in the system. I'm surprised nobody else offered this advice...
The way I do it is to, obviously drain it, get it up on ramps (or I suppose a jack would do the same), then fill it - with the nose up in the air, you'll get the coolant fill higher than any other part of the system and therefore avoiding any chance of getting air trapped.
 
I'd replace the thermostat 1st, then flush and fill and BE SURE you don't have air trapped in the system. I'm surprised nobody else offered this advice...
The way I do it is to, obviously drain it, get it up on ramps (or I suppose a jack would do the same), then fill it - with the nose up in the air, you'll get the coolant fill higher than any other part of the system and therefore avoiding any chance of getting air trapped.

...or fill it from the thermostat housing. Burping the system may solve the problem but I've never had an issue with a little air causing drastic overheating. Usually just causes a low coolant light.