Need Help with cooling system questions...

[Happy Hummer]

2007 H3 Base 55K approx...


This started approx a month ago and is getting noticably more apparent with the days.


Issue:
Upon starting the H3 it will warm up to 1/2 mark on gauge and will remain there after the warm cycle unless:


a) Standing still you apply the accelerator firmly (say 3K rpm) and then the temp guage will fall 1/8-1/4 the way down the gauge


b) Driving the temp gauge will fall when accelerating to pass another car


I've already inspected the belt, tensioner pulley, rad cap, all surrounding area for site of leaking or dampness (None)(OK)
I've made certain all fluids are correct level and there is NO fluid contmination (based on visual inspection)


If the H3 is at 1/4 of the temp guage when 1st warming up in the morning and the pedal is depressed the guage does not drop.


The plug for the CTS (thermister) has been cleaned and replugged.


Please Help with this if possible.....


Chris

 

[Happy Hummer]

Heat blows Hot...

Chris

 

[Kyle]

have you checked the water pump?

 

[cbetts]

Almost sounds like the thermostat is stuck open. If memory serves me right, most H3's normal operating temperature is right at the middle mark (I never pay attention to mine anymore with the ScanGauge connected). Once the RPMs pick up, water flows through the radiator more along with more air being pulled through. Only other guess would be an air pocket in the cooling system.

 

[poncho1965]

I am getting the PO128 code on the check engine light. Ambient temps are lower and my gauge is running at the 25% mark. I have a new thermostat to install but have not been motivated to change it yet...


Mike

 

[Kyle]

How bad is it if the thermostat is broken open? wont it just run cooler?

 

[alrock]

If it is stuck open, the engine is not operating as hot as it should which can result in decreased efficiency and lower mpg.

 

[poncho1965]

Agreed. Changed out my thermostat today. It was cold, and closed as it should be. When I was done fired it up and within 10 minutes, the temp gauge was at half way on the gauge. It hasn't been there in months. Will get my check engine light reset tomorrow. I left the fender well liner out, will get my CB antenna mounted soon!



Mike

 

[Zach]

Agreed. Changed out my thermostat today. It was cold, and closed as it should be. When I was done fired it up and within 10 minutes, the temp gauge was at half way on the gauge. It hasn't been there in months. Will get my check engine light reset tomorrow. I left the fender well liner out, will get my CB antenna mounted soon!



Mike

After a few engine cycles and miles driven, the CEL should reset itself.

 

[poncho1965]

After a few engine cycles and miles driven, the CEL should reset itself.

Good to know, thanks Zach!


Mike

 

[Happy Hummer]

Thanks all,
But as stated it blows nice and Hot and does not get cool/cold when the temp gauge drops the 1/8th-1/4 when depressing accelerator. It in fact blows much hotter as it should. The H3 take the same amount of time to warm up as last winter and the engine is smooth-ish running...Lol!

I was talking to a buddy the other day and he commented the it seemed hard to believe that the CTS would be sensitive enough to vary the temperature in 3 seconds and then reset the temp gauge back to center line in a moments notice if it were a fluctuation of fluid temp.... The fluid cool down would happen if the t-stat was hung open ...(if it were the antifreeze cooling down that quick there would be less heat not more!!!)...He had some good thoughts there. I'm beginning to wonder if the tolerance values for the CTS are possibly out of acceptable parameters because of corrosion or age?

Chris

 

[ArtHummer]

Hi Chris,
Didn't you replaced the the thermostat not that long ago? I think I remember from the previous posts.

In my opinion you have an air pocket somewhere near the temp sensor. The temperature of coolant can not drop that fast. It can happen only in two cases. First is that is some kind of electrical problem. Or, the coolant is not getting on the sensor. And it kind of make sense... When you accelerate, the water pump starts to pull more and maybe at that point the air pocket reaches the sensor. When the sensor is not covered by water it will not register the temperature. After few second the level stabilizes and pushes the air pocket away, so the sensor starts to read again.
Try bleeding the coolant system, it might fix the issue. If not I would think it is something electrical.

 

[Happy Hummer]

My gf's H3 was having difficulties but with help from forum members was resolved with
burp'n.
Mine still has tstat that came in it.

Chris

 

[Reloader]

I'd start with a new t-stat and a temp sensor with a new pigtail connector. Usually a bad stat in a GM will set a code for inefficient warm up time but not always. The sensors can be bought with or without a replacement pigtail connector. You want to solder the new connector in place. A little green death in a connector can cause lots of issues and can be impossible to completely remove. Another thing to check is the fan clutch. If its siezed up and wont release it can pull too much cold air over the radiator. You will hear it roar loudly if its locked up. Not sure if the I-5 has a viscous type or an electric type like some Trailblazers have.
Most cooling systems should purge the air from them after a few drive cycles provided the recovery tank is kept full.

 

[Happy Hummer]

Hello have had the chance to use Happy numerous hours and many miles with No problems whatsoever save for the temp gauuge. You roast when you're inside and after the proper period of time for warm up can turn engine off and fan spins freely. So no problem with the clutch any other thoughts because I'm leaning more more to just a simple idiot sensors.
Chris