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Author Topic: Again... Another one overheating (Think I have it narrowed down)  (Read 2210 times)
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Posts: 12

« on: March 27, 2012, 03:59:26 PM »

Hello guys,

I have been lurking around on here reading up on overheating issues, because guess who else has one!


Randomly would get close to redlining, then cool back down, as if a thermostat finally opened (hmm..)
This would be highway or city
AC would be cold, do not know about heat as it was 80 out.

Throttle position sensor
Idle Air Sensor
(It had some high RPM issues too)

Now the symptoms:
Will heat up when stopped
Radiator Fan does not appear to be turning on

Cooling fan relays

No avail, although the 5 pin was hard to find and I only got one 4 pin, I have not swapped around the 4 pins since getting the 5 pin, I will try that in a minute.

Any directions guys? I am not sure the temp, because well It doesn't have any numbers!! It gets up within 1/8th of redline though in town. Heat worked fine this morning into work (30min).

Glad to say my high RPM issues seem to be resolved.

Thought though, how does the computer know the engine temp? Is it the same sensor the gauge uses or a different one? Maybe the sensor feeding the computer is bad?

Sorry if this is all over the place, try living in my mind!!! I work on computers for a living so my thought process jumps around.

OH. It is a 2001 Base with 170k miles. Other then this heating issue it is a great car, even being 11 years old and creeping up on 200k miles. Just did a couple thousand dollars worth of work on it to keep it running to 250-300k Sad

Edit: Swapped relays, resat fan connection, no avail.

Edit2: Fans do work, they just don't come on until it is 1/8th from redline. If the AC is on they will come on as normal.
« Last Edit: March 27, 2012, 05:05:30 PM by Bunnywinkles » Logged
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Posts: 30

« Reply #1 on: March 28, 2012, 11:12:13 AM »

I was going to suggest the engine coolant temperature sensor.  This device supplies a signal to the ECM to turn on or off the cooling fans.  However, it appears that you've already addressed that in your last edit.  Have you by any chance notice the slightest whiff of antifreeze?  Any kind of overheating problems will be enhanced by even the very slightest coolant leak.  Other than that my Aztek operates similarly to yours and I've just accepted it is normal.  For your information the fan should come on low when the temperature exceeds 223F and it should come on high when the engine temperature exceeds 230F.  If the A/C is turned on and is developing pressure over hundred 190 PSI both fans will come on. Good luck let us know. Ron
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Posts: 12

« Reply #2 on: March 31, 2012, 05:34:49 PM »

Well, I thought I had her fixed, then today AAA saved me.


Overheat light came on, bell chimed
Heater blew cold
Res seemed like it had too much coolant (Possible air in system)
Top radiator hose was hot/warm
Oil did not seem to have coolant, but only looked at dip stick.
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Posts: 197

« Reply #3 on: April 01, 2012, 10:24:36 PM »

Does kinda sound like air - specially with the heater blowing cold....notice any change in the temp gauge with speed?  If she heats up when stopped or doing 30 mph driving around town but then cools back down when you open her up on the hwy, that's a sure sign you've got air trapped somewhere...open the bleeder screws up and see if you can get her to burp.
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« Reply #4 on: April 05, 2012, 02:17:00 PM »

Found a very small leak in her. I don't know what part it is though its on the front passenger side of the engine, there is like a "t" there. It appears the o-ring joining that to the engine is leaking. Its a small leak, but it was leaking. Hopefully that is the only place.
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