Topic: Engine coolant temp fluctuating

[DickW]

In the last few days my Coolant temp has been spiking to as high as 223. It will spike up to that then go up and down between 200  and the high teens/low 220s. I took it the dealer and he test drove it and said the highest it got was 208.
 I suspect a flaky thermostat, but they won't do anything till it becomes consistent.
Any ideas?

[wspohn]

I have watched mine do the same thing.  Probably the recently reported problem with the cooling system and air pockets, not the thermostats.

[Ben L]

There is a foil insulated coolant line near the firewall that Joe once yanked on, to cure a momentary high temp reading on my car.  Perhaps he or someone else can chime in and advise as to its location and what goes through it.

[DickW]

I have never added coolant or even had the cap off.

[ThunderSky]

Mine did the exact same thing a few weeks ago. Took it to the dealer, could not replicate so.....same thing. Dealer would not do anything.

It was better the following week or so but I now have the car in storage till spring. 
We'll see what happens then...

[DeepBlueGXP]

Lil Goat sent me an email about GM will be adding two check valves to the coolant system for GXPs late December to prevent the system from sucking in air when you remove the cap.   

[spicy3480]

This happened to me also...dealer replaced my thermostat and the it came back.  It happens every now and then still.  Although, my coolant seems to drop an inch or two after I fill it and drive about 100 miles.  Nothing leaks under the car.  I am guessing it is a slow leak as I drive and pressure is in the system, but not sure.  Any ideas?

[TomatoSoup]

This happened to me also...dealer replaced my thermostat and the it came back.  It happens every now and then still.  Although, my coolant seems to drop an inch or two after I fill it and drive about 100 miles.  Nothing leaks under the car.  I am guessing it is a slow leak as I drive and pressure is in the system, but not sure.  Any ideas?

One of the classic symptoms of a failing cylinder head gasket is loss of coolant.  

Haven't seen anything about failed gaskets on the forums, so don't know if it's likely, but techs can test for this using a sniffer in the oil filler tube.

Just a theory.

[Uranium-238]

*raises hand*

I've been loosing slight amount of coolant ever since buying the car. It's those lousy clips on all the small coolant lines. The three on the T-fitting by the reservoir, and there's another on the radiator I just noticed has some red goo around it. I've been changing them out with band clamps, they're not the best, sure, but they work.

[DeepBlueGXP]

I"ve topped off mine 4 times since I bought it and today I had another coolant light.

[Critterman]

The only time I have added coolant was when we took the radiator out to do the stage III upgrade

[Rogue]

An air bubble can cause that problem. The void fills with high temp steam and spikes the gauge as it passes by the senser. The most typical cause is a slow leak somewhere in the system. However, some cars (kappas?) suffer from this when the fill point is not the highest point in the system. If that's the case, the coolant needs to be filled under pressure in order to fully evacuate the air. Maybe that applies here, maybe not...I'm not familiar enough with the design to say specifically. Does the factory manual detail the fill procedure?

[DickW]

Rogue, that sounds reasonable. How do you check for an air bubble? How do you get it out?

[snaponbob]

Hopefully I am not about to curse my car, but since late October 2006 and 24K miles the coolant level has not budged. So, an observation on the above comments --- there are two common comments; 1) 'yup, just started doing that', and 2) 'been doing that since I bought it'. #1 = this observation - the weather has changed to cold. #2 = look for some seepage at clamps.