O.k. Another over heating issue/question. I had my radiator cleaned, and the problem persists. In stop and go traffic, my temp needle begins to climb, and eventually rests right above the 3/4 mark. The truck becomes EXTREMELY sluggish off the line and at part throttle. I'm assuming it's pulling timing because it is getting hot. The only problem is it almost got me killed today when I was trying to turn into a parking lot from the middle lane(across oncoming traffic). Pressed gas, started to turn, and the truck fell flat on its face. press gas a little harder, hardly moving. Stomped gas while yelling expletives as oncoming traffic starts to get REAL close, and the truck finally starts building speed. This is getting stupid. What is it? Any ideas? Truck cant be running that hot as to pull timing to the point of almost stalling. Transmission shifts fine. No warning lights. Almost like the tranny is starting in 2nd or 3rd gear. I'm going to call the dealer, and take it in tomorrow, but I wanted to get yall's opinion first. Seems I cant shake my damn flooding incident, stuff seems to keep popping up down the line. I just paid $400 at dealership to have the radiator pulled and cleaned, because they said hats what was causing the running hot before. Do you think its the Tranny? The Engine?

 

Have you tried to run a different coolant? watch out 'cause some aren't anti-freeze too but try to find a high performance coolant that still has anti-freeze

 

Josh, don't know what all they have done but I assume fuel, air filters changed, thermostat, etc. You say they charged $400.00 to flush the radiator I would tell them that since they misdiagnosed it the next one is on them. They are the professionals and you don't pay them to guess. Who is your dealer?

 

DeMontrond Hummer in Houston, Tx. The air cleaner is perfect. They already replaced the evaporaitve canister in the fuel tank. I changed the diff. fluids and oil. They cleaned the radiator, and I have since pulled off the grill myself and rinsed it again thoroughly. I really don't know. I understand that maybe the H3's run a little hot, but this doesn't seem right. The temp will fall to slightly above mid point when on the freeway, but the sluggishness returns at next red light. Once underway, eveything is fine. At low speeds, like going from stop sign to stop sign in a neighborhood, the truck is an absolute DOG when temp needle climbs. I just don't want to go to the dealer tomorrow, and have them say "Oh, well you broke this, and now we need $500 to fix." I would appreciate any insight!

 

i have the exact same issue! tried everything to resolve. im going to drain cooland and oil and replace with a better oil.. see if that works. i super cleaned my radiator. and still have issues!

 

same here. city traffic, never reaches max, but totters on 3/4 mark. but once up to speed. it cools down... not all the way, but it does cool. And the lack of power is extreme and you hear loud fan nouse and a long woosh sound from take off!

its really getting onl. lol. im getting an intake and pcm this week. mabye that will help? but either way. im going to figure this out!

 

When a GM clutch fan vehicle gets hot, like you are describing, the timing is retarded by the PCM (power makes heat) and the clutch on the fan engages to pull aif through
the radiator. When hot, the retardation of timing does significantly change performance, not to the point of stalling, but a very noticable drop off in acceleration.

I can only guess that you should have them test your thermostat??....and make sure you do not have more than 50% coolant to water mix (since the dealer worked on it I we assume they put the GM red antifreeze in the system).
You can alsoadd some Redline Water Wetter to the coolant to help with any cylinder head hot spots, but it really will not lower coolant temp overall.

 

will a pcm tune fix?

 

I've already added Royal Purple Ice, (same type additive as Water wetter). Didn't help. I also noticed that A/C performance drops off when this happens. The air go's from cold w/ no humidity to cool w/more humidity. Hummer replaced my A/C compressor a few months ago. It had started to whine during acceleration. I don't know what to do![:@]

 

I do not think so brud. For some reason your coolant temp is running a bit high, that needs to be addressed, maybe a visit to a local rediator shop for an inspection??