I opted to throw this on the board looking for any info.

I own a 2005 H2 - with 58,000 miles
Here's the deal: Engine running great. I feel a slip in the trans shifting from 2nd to 3rd. Then notice antifreeze pouring out the overflow. I shut down the truck and had it towed to the dealer. The diagnosis is: The trans cooler bursted in the radiator mixing the antifreeze into the trans and blowing the trans. They say the entire cooling system needs to be changed, rad, hoses, clamps, heater core, etc. and then the trans plus the trans cooling system. cost $7600 AAGH!

The H2 is out of warranty. I called corporate and they are investigating the issue. The truck has never been in the dealer for any repairs. All maintenence has been done by me. Oil changes, greasing (the basics).
Corporate has been investigating for 1 week now because they claim that if the truck was taken to the dealer for maintainence this may have been avoided. I think this is bull**** and sounds like a part failure to me.

The truck has some mods: Intake, borla cat-back exhaust, shift kit and diablo programmer.

Wondering if anyone else has had a similiar situation. Also any feedback is appreciated

WOW that sux, guess they will be replacing the old radiator, carefully remove the tank end where the trans cooler is, look at the trans cooler see why it failed...


You gotta give me a good reason to replace the cooling system! I see no reason why you cant clean it and reuse the parts.

Try going to the Hummer sites see what the Hummer YODA's say? Their has to be a site like this one for Hummers?

They claim that they can't guarentee all the trans fluid will be flushed out.

Yes I placed this on 2 Hummer sites like this one. I know most members on this site are "highly trained techs" with great common sense abilities- so lets hear what you guys got to say!

If you cant flush the heater core, radiator or hoses ask the money grubbing mutts how the hell they are going to clean up the inside of the Engine?

Sounds to me they are use to handing out over inflated bills and a stack of bullshit on a daily basis, based on their rule of thinking you need to replace the Engine too because your not going to clean it up any better than you could the radiator or heater core.


I ASSume the radiator is all aluminum and has black plastic tanks on each end? I would go get the radiator from the morons and take it apart, I would carefully remove the end tank where the trans cooler is and see why it failed then off to a radiator shop to find a replacement trans cooler and have them flush the radiator, you might just want to hand the whole thing off to a radiator shop, me, I like to play with things... If you cant find a replacement trans cooler maybe you can just add a external trans cooler?

That radiator just fit the Hummer or is it the same one they use in trucks and SUV's cars and whatnot ?

They replacing or rebuilding the trans?


Chicken or the egg came first????

The trans had something fail and that created a over pressure situation that sent more pressure to the trans cooler than it could handle?



Shift kit and programmer created the problem by increasing the line pressure to the cooler then it split or this was simply a defective cooler?


After market add on crapola is never a good good situation MOST after market goodies come with a penalty of some sort, some quick examples
http://pilotodyssey.com/PO/viewtopic.php?t=2687
http://pilotodyssey.com/PO/viewtopic.php?t=2688
http://pilotodyssey.com/shocking.mpg
You might research every option and setting you added to your Hummer to ensure it could not have caused the problem so you don't repeat this again in the future.

Just got off the phone with the GM at the dealer that did the diagnosis.
He says he got me $4000 from Hummer corp. And now he will be able to bring my side down considerable. It seems like the GM was at bat for me. He has a radiator on the floor which will give me for have price. All hoses must be replaced because the trans fluid will eat the rubber. As for the core, flushing is sufficient. He suggested a brandie new transmission. The trans would have to be torn down completely and then rebuild, he says the difference would be about $1000 for the new one. And the new trans comes with a 3 years 100,000 mile waranty - that right there is worth the $1000 bucks.
So I have chose to stick with him and have the dealer do the repair. Seems as though it will cost me out of pocket tops $2000.

$2000 - New radiator with trans cooler, all new hoses, brand new trans with warranty. Flushing the systems with all new fluids. Seems reasonable to me.

$2K you did killer!!!

take that and go with it, even at $7K it was a fair deal for a dealer or shop to give, they got to cover their ass on such a project, they leave off a hose and it blows and in turns over heats and warps a head, then they might take it hard.i
But If it was mine and i was going to get stuck with it, i would do a good flush (not backflush), change to a separate remote trans cooler, get new radiator, drain everything from trans and converter, refill and go with it, after a few hundred miles do a jiffy lube trans fuild change just to be sure and see how it goes, nothing lost except lots of trans fuild if it don't work

I have also been posting on a Hummer forum......Seems this is a common problem and the # is at about 3000 trucks. The problem seems to be in the internal cooler system. I am going to run with it. Just as Hoser says...the mods on the truck definitely impacted the situation. May not be the cause but definitely impacted it. I will not be putting the shift kit back in. But I will be running a larger external trans cooler once the truck is returned to me. As for the $2000 - I think it's a deal to have a brand new out the box tranny installed with a 3 yr 100,000mile warranty. Plus th radiator and all new hoses........no doubt.

Thanks for the links...It's funny because I have read 2 of the 3 and agreed.
As stated I will not be putting in the shift kit. This is an electronical trans and should be ran the way GM build it. As for the other mods I will continue running the truck with them.

THE FUNNY THING IS ALL THE MODS WERE PUT ON THE TRUCK WITH ONLY 25,000 MILES ON IT. AND IT HAS RUN STRONG WITH NOT A PROBLEM UNTIL 58,000

thanks for the imput - I will be back once I get the truck back and install the cooler.

Thanks again ALL

I am no trans guru by any means and 33k miles is a long way for sure however some adjustments if not correct can damage a trans a little at a time over a long period of time, for example when researching swapping and properly setting up my 700R4 trans into my 72 GMC I read in more than one place if you don't properly adjust the TV cable it will damage the trans, depending how mis adjusted it was it could burn out in 1000 miles or take as long as 25k miles or longer, regardless of the reason why yours failed if you don't find the root cause of the failure and correct the problem it will happen again I hate to see you do this all over again in another 33k mile$

The order at which this did accur is:

Trans cooler failure - the "plastic casing" is what "caused" the failure. As the Hummer forum guys stated 3000 trucks have had this problem. Most guys on the site have already changed over to an external unit. The trans failure was cuased from the "beptol bismol" (coolant /trans fluid mix) getting into the trans and causing the slippage.

Hare stated above that the trans slipping doesnt means it's actual bad.....just may need to be flush a couple times through and she may be good. But for the $2000 getting a "new" trans with the warranty( 3 yrs 100,00miles) on it is definitely better than flushing it, hoping its good, and then not being good and having to replace it out of warranty.

I am continuing my research through the hummer forum on others set ups and will hopefully tweeak the complete set up this time around.
I tend to forget it not like throwing together a 1969 350 chevy anymore. All this computer stuff is entirely new to me. It's a learning proccess and I think I just got taught a valuable lesson at hummers expense....so THANKS YOU HUMMER.

If GM hasn't had this problem with numerous other vehicles they would have never dipped in their own pocket to make good on their part. The 2 grand is a great price for the customer. Don't tell the dealer that you had the shift kit in it, just play stupid if they metion anything, which they won't because dealers typically don't tear down transmissions. They should be able to clean the ATF out with lestoil. I get the plow trucks in all the time with the same problem you had (cooler popping). The cooling system gets filled with lestoil and I run the Engine and drain it. Do this a bunch of times to get all the junk out. It works very well. Good luck.

Lestiol huh, no way I never thought of that when it came to this sublect, we too have many issues with the coolers on our snow plow trucks going bad, but we have never ( to my knowledge) used that to flush out the sytem,I'll have to mention that to our guys in the shop-thanks for the tip!!!

Many of the newer GM radiators have a trans cooler built in on one side and an Engine oil cooler built in on the other side. If yours has an oil cooler tank, I would take a good look at it also. It may be the exact same POS tank as the trans cooler that broke. If so, look around on the hummer boards and see if people are having the same problem with oil cooler rupturing. The oil runs through the cooler at high pressure, and if it is the same tank it may eventually give you trouble also.

After the repairs I would divorce the factory trans cooler. I don't care for the cheap aftermarket external coolers. Those cheap mount kits that are like zip ties put through the radiator will wear holes in the radiator core eventually so build brackets to support whatever cooler you install. I usually go to the junkyard and find factory external coolers off newer vans and mini vans and use them. Plus you can look around a bit and find sizes not available at auto parts stores for a better fit into your application. They are of a much higher quality than aftermarket crap and usually come with built in brackets and rubber isolated mounts that you can quickly adapt for an easy installation on your current vehicle. You can have them pressure flushed at a radiator shop so they are nice and clean inside before installing. Expect to pay $10 - $20 for a nice size cooler from a junkyard where as you pay usually at least $50 for a decent size aftermarket cooler that is of low quality chinese made junk from places like Auto Zone. Also, if you live in an area with cold winter weather you can install a bypass thermostat for the cooler so fluids aren't being cooled during warm up. Here is a link for a bypass thermostat:
http://www.motors.ebay.com Item number: 320061091107

Yes bypassing the stock intercooler was the idea. I spoke with many on the hummer board and the oil coolers are working just great. It's only been the trans cooler giving way. Most guys on the hummer board install a trumax intercooler - all praise it. It's about $115. So I'm likin your idea about the junkyard grab. A close friend happens o own one. So I will be heading to see him. Thanks for takin the time an replying.

I picked up the truck today.

New overflow bottle
New radiator with trans cooler
All new hoses and clamps
New Trans with 3yr/100,000 mile warranty
Flushed the system
All new fluids

Total $8300

Hummer picked up $5200
balance $3100
Dealer discounted me and my end came to $2100

I will be installing a external trans cooler in the near future.

I have not seen a trans guru yet that did not say to keep the radiator trans cooler when adding another external cooler, this keeps the trans fluid warm , too cold of fluid is as bad as over heated fluid...

Yes, the unit I am purchasing has a thermostat bypass which closes to by pass the fins and keep the fluid at temp. It's a pretty cool set up.

If you are going to be putting in a bypass cooler kit then be sure to add a trans temp gauge. 90 % of the aftermarket stuff out there is complete junk, 9% is ok and 1% is excellent. I've seen on the some of the ford automatics with a factory bypass for the trans cooler, where the cooler plugs/bypass sticks or fails and the trans oil is pumped right back into the trans uncooled, the unsuspecting driver ends up cooking his trans. A $20 gauge would have saved the trans.

Like I said I have not seen any trans guru say yet to bypass the cooler in the radiator.

The truck has a stock temp gauge. Seems to stay steady at 170-175 degrees. The water temp gauge hangs at 195-210 degrees. When this accured the trans temp was the same as the water temp.
I think I can trust the stock gauge tin the truck. Any movement from the 175 degree mark would mean a problem.

Here Hoser you can read what the Hummer boys had to say:

http://www.elcovaforums.com/forums/showthread.php?t=23002

Hopefully the link will work without a password.

The truck has a stock temp gauge. Seems to stay steady at 170-175 degrees. The water temp gauge hangs at 195-210 degrees. When this accured the trans temp was the same as the water temp.
I think I can trust the stock gauge tin the truck. Any movement from the 175 degree mark would mean a problem.[/quote]

Modern day cars use a computer to transfer the data from sensors to your instrument cluster. They are not acurate in reading quick fluctuations. Remember how your fuel gauge use to fluctuate when you would hit bumps going down the road, now they don't.

Link worked, I would still go find a trans site to ask trans questions...

"45,000 BTU rating " numbers you gotta love them , so how many BTU's does your transmission generate?

"The only disdavantage for places with cold winters is that there will be no heat exchange between Engine coolant and tranny ATF, so the tranny may take a while to warm up. Optimum operating temp is around 175F. It doesn't get that cold here, 50F on a real bad day, but my tranny still gets up to temp just fine. Running a little cold for a while should not be a big problem."

Should not be a problem? He a trans guru?

What transmission do you have?


http://www.transmissioncenter.net/highperflist.htm

http://www.bowtieoverdrives.com/index.shtml