I can leave mine running in 96-98 deg at idol and after 20 min. it may get just abouve the 1/2 way mark but drops to norm after about 50 ft of parking lot driving. sounds like the dealer doesn't have a clue. sounds like it a thermostat sticking.

 

I run at halfway most of the time. Last weekend it was 112 on the highway between San Diego and Phx. Cruising at 80 mph, the gauge was at 3/4 for an hour+. It bumped above 3/4 for a couple of good sized highway climbs. I also had a loss of power as I tried to push it to catch up someone - the vehicle just didn't want to go. No stalling or hesitation, just reduced power. Of course I don't think the H3 is really happy above 90 mph

 

here is some food for thought. have the dealer install a data recorder on your hummer and when you go into reduced power, you just hit the button which will record all of the ecm inputs and outputs. they can then down load it and look at engine temp, engine load, throttle sensor
and anything else that could affect the runability of the vehicle. also on the dealer world web site there is the diagnostic chart for testing the fan clutch which the dealer has access to.
with everything described i still say fan clutch.

 

Well, still havn't heard back from the dealer. Called yesterday, and left message, but no reply. I'll try to call back today. I'm assuming if it has taken this long, they have diagnosed and or changed something. We'll see..........

 

any word on the problem? what was it?

 

Well i went to pick it up, and they told me everything was perfect, and they didn't see why it was doing it. Said all Alphas run hot. I said B.S. ,and i'm gonna take it to another dealer. Frustrating as hell. [:@]

 

sounds like my dealer. like we have time to bring our trucks in when there's nothing wrong. let us know when you get it resolved and be sure to tell us which dealer set it straight

 

Has Hummer been able to diagnose your overheating problem yet? I live in Phoenix, AZ and have an 08 Alpha that is experiencing these problems too. Doesn't overheat while driving around town or on the freeway. But last weekend we were doing some offroad exploring in the 100+ degree weather and the temperature gauge went right up to the redline.

At the time we were going up a slight incline and the engine power went down so much that with the pedal to the floor and the transmission in 1st the engine would not build up any power and the vehicle just wouldn't move forward.

I would like to take it into the dealer and tell them to just fix it, but it would be nice to know if anyone else has had a positive experience with taking it in to the dealer for this problem.

 

They replaced my fan clutch which helped a little, but i still have the issue. I've pretty much given up hope. I heard there might be a TSB about it, but we'll see........[8D]

 

Here's something I have found to be a very effective way of cooling the engine when you are out and about:

Stop, put the truck in P or N and then rev the engine to about 1300 - 1500 RPM. You will hear the fan sucking in a LOT of air. On my truck, I can actually SEE the temp gauge needle move down towards 50%. When I am running trails, I find that doing this for 3 - 5 minutes will cool the engine substantially. -Of course if the weather is 100+ degrees this will take longer and may cool the engine a little less, but it has always worked for me.

This is of course only a treatment of the symptom, not the underlying problem.

Good luck :-)