So today I was at the boat ramp, launching my boat. Like I always I do I leave the H3 running while I dock the boat and run back to pull the trailer out. Today the dash read "A/C off" and it was hot inside. I was gone maybe maybe 10 minutes. The Temp gage was all the way to "H". We went ahead and played at the lake, on the way home the temp would be about 3/4 the way to the "H". As I sped up the temp would drop some, but would climb again when we would stop or have to drive slow because of traffic. Im assuming this is a thermostat problem. Any advice?

 

id let it cool down.
check coolant, fill?
run till its up to just under mid.
if it goes higher it could be a stuck ts,or??.
i keep a piece of screendoor screen in front of my rad to catch junk,so the rad never gets clogged, toss it or shake it out.
my exp with 2 h3 3.7 is from -20f to 100f, when warmed up they sit just under the mid point
unless u are pulling a load,up hills??. i dont do that.
mine never moves from that point, thats the thermostat setpoint

 

does the "tow package" include a larger Tranny cooler??? Just a shot in the dark here but maybe the trans is heating up so much its transferring heat to the motor and or radiator? Trans service should be more frequent when your towing stuff, and a larger aftermarket cooler is a must if your tow a lot!

 

I only tow a popup about 2200 lbs, and a small bass boat. Come to find out I was almost a gallon low on coolant. I guess my GM service I had two weeks ago isnt as thorough as I thought. Filled the radiator back up, and filled the resevoir to the fill level. Ran the H3 for about 30 minutes in the driveway with the A/C on and it stayed a needles width below the half way mark. Funny how that works!

 

a GALLON low? That's about what it took to fill back up after removing my old radiator and installing a new one! That's almost empty unless you are counting the overflow coolant tank in there too. I can't believe the dealer didn't catch that!

I think someone hit on a good point, here when the temps are over a hundred I think the transmission is putting too much heat into the radiator. Especially with the A/C on as well. Unfortunately, the Adventure and "tow" (I have both) packages do not include a larger or separate cooler. I read on another board of someone running a separate transmission cooler but it needed to be pretty big because they were running high temps with the stand alone cooler setup and went back to stock.

 

If you have it happen alot I'd consider an aftermarket electric fan.... there are a lot of companies that make them. I got a great one off of eBay...

 

might be a bad heater core? (i think thats what its called) i started smelling antifreeze in my truck when i turned on the ac about a month ago so i checked coolant and it looked fine. a few days later, i came out from a business, started the truck, and ac off light came on and steam came thru the vents. temp went to high so i checked coolant again and it was EMPTY. added some water and tried to get to my dealership. i ended up having to get it towed cause i stopped for about a half hour to let it cool and it wouldnt start back up. turned out to be a bad heater core

 

interesting on how the dealer didn't catch that, maybe it was caused by a defective employee

 

Sucks to hear about your friend who failed with the aftermarket tranny cooler????? I just scored a tranny cooler off a 2500 Sierra HD we pulled the engine out of this weekend and plan to tie it into the stock system on the H3. Hope my results are better! That is just sad!!!!! Lucky you didnt burn anything before realizing it was a mistake on the part of someone you paid good money to do a thorough job!