I am afraid I broke my wifes H3. We drove up I-79 from Charleston WV into PA on our way to Philly for a wedding. After I got through all the mountains and was into PA I noticed the tranny seem to "flutter", by this I mean not really slip, but feel like it was going to. No check engine lights, no rise in temp. Nothing, just a flutter every once in a while. I was almost to my parents so decided to keep driving until I see any other warning signs. Eventually I ran into some red lights and noticed on take off the tranny would hang between 3rd and Drive. I would ease off and let it settle into drive. Still never heated up and no warning messages or lights. I made it to my parents and opened the hood. I noticed the coolant reservoir (dex-cool) was overflowing slightly and seemed a little "muddy" looking. I got out the maglite and sure enough there was a layer of what appeared to be tranny fluid on top of the red coolant in the reservoir. There is a GM garage 2 miles from my parents so I decided to drop it off tonight and leave the keys. On the way there the Engine Hot signal appeared and the tranny was really slipping. I was close enough to slide it into neutral, shut the engine down and drift the last 1/4 mile into the lot.
My stomach is upside down, and it's hard not to be depressed as I sit here in my hummer T-shirt and hat to type this, all while knowing I have to rent a vehicle to finish the trip to Philly in the morning. A trip I was looking forward to showing off our new toy during. Ecspecially after a great week in OBX with many pictures.

Has anyone else ever had this problem? I am hoping it's a tranny cooler problem which would lead to the tranny fluid in the reservoir instead of the tranny, which of course would lead to the slipping.

 

There's been reports of a few H3's with this problem. The tranny cooler in the radiator goes bad and the trans fluid and coolant mixes both ways. Not a good thing for the trans or cooling system. Hope its covered under warranty cause you're lookin at radiator and transmission replacement..minimum. Let us know what they find and how it goes

 

Called my friend at Hummer of Louisville. R Graham is correct. They have serviced two trucks, both 06 models, this year for the same issue. The trans cooler ruptures causing a mix in fluids. It apparently is worse in hotter climates. The first H3 they serviced was fully covered under warranty, fixed and out the door in four days, loaner truck included. The second fella had an extended GMPP warranty on a 65,000 mile truck. The lowest selectable coverage, drive train only. The Radiator wasn't covered. Since it was the cooler and radiator that failed, GM covered nothing. He had to replace the engine. Transmission, radiator and lines. 11,000 buck. Hearing that $#%T makes me sweat bullets!


Keep us posted man, and good luck.

 

Welp. That sure sounds like ours. We have an 07 with less than 30k miles on it so I it should be covered under warranty. I should be able to find out within the next two hours but won't be able to post until sunday evening. I will let everyone know.


Thanks for all the info guys!

 

WOO-HOO!!! Just got back from the dealership (certified GM garage). The owner is a family friend and came in early to look at our H3. Definitely has coolant in transmission and will probably need replaced along with radiator/ transmission cooler. Dealership owner told me "Don't worry, go have fun with your friends in Philly, you're completely covered even if we have to put a new engine in it, well have you fixed up"

Headed to Philly in a HEMI and feeling much better about my HUMMER now.

 

I can see were the tranny would need to be replaced/rebuilt because of slipage and damage. Hopefully not the engine? Tranny fluid in the coolant could be flushed out. I think it would take major overheating to cause an engine replacement. It sounds like Rideacanyon shut it down pretty quickly.

Mike
06 Hummer H3

 

the same thing happened to us in our 2007 on a long journey and it was fully covered by the warranty. does anyone know if you can make the transmission cooler separate. so that this doesn't happen outside the warranty period as there is obviously a known problem which causes this.

 

Unless there was an overheat situation, I sure do not understand replacing the engine.

 

I talked to the garage on Friday and they told me it was definitely the transmission cooler that started it all, and it would be completely covered by the warranty. They were told they have to completely disassemble and rebuild the transmission with a new torque converter and so on. I will have a new rad/tranny cooler also. Engine was coolant system was flushed and no damage. They said it will be atleast 1.5 weeks. Add to that it is 5 hours away from my home. Garage Service Manager did tell me he would honor my warranty if I added a seperate tranny cooler, once again, this is a family friend though. I will wait until 100k and then add one. For now I have to let my wife drive my HEMI to work, going to be a long couple of weeks but in the end it won't cost me a penny.

 

The exact reason I installed an external tranny cooler just about as soon as it was out of warranty. I never liked the idea of pairing them that way, Just an ignorant design.