At least GM designed it's crack feature into almost the very top of the radiator. It won't dump all the fluid at once and leave you stranded on the road. You can always nurse your truck back home and drive around for a few days while waiting for UPS to drop off the replacement.

It took me about $200 total and 2 hours to replace mine on a nice sunny day so I'm not too upset about it!

 

With this thread "finally" thankfully stalled, here again is the link for instructions to replace your H3 radiator yourself.

Most men can do this job themselves ... if they're are so inclined.

https://www.hummerforums.com/forum/h...uctions-29122/

 

After monitoring this thread for a few years and waiting for the day mine cracked, it has finally happened. I have a 2006 H3 and at 57k miles the radiator has fractured across the top near the seam.
The leak is luckily slow, with only a few splatter marks across the hood, which allowed me to finish a hour and a half drive back home.
I decided to purchase an aftermarket radiator and new hoses, and will be installing later in the week. I'll take pictures and post if anyone wants to see.
Also, i've only offroaded a few times and it was mild haha. I only recently started towing as well.

On a side note, Hummerforums has saved me time and money on many repairs/preventive maintenance. Love the site, just don't comment much. Cheers

 

Another radiator bites the bullet. My '08 H3 started leaking 2 days ago, when to dealership this morning and yep leaking at top of radiator.....sound like I am in the same boat many of you are. Dealership is ordering a new GM radiator and will install next week. Contacted also GM Customer Service and got a Claim ticket entered and may know more next week on if any help with the cost. My '08 has 53,200 miles and has been abused so we'll see. This thread helped me a lot when talking with CS for I was able to quote more info than the average driver so thanks to all that posted info.

 

If anyone else can PM me your claim number to reference that may help my status

 

I want to know if the dealer keeps theses cracked rads for rework?
If someone has a cracked rad that is being replaced,AND it is not needed or does not need to be turned in, I would like to get it for a test repair with fiberglass/epoxy as i have heard about here. i have done some workmlike that and want to prove out the concept.
Can you make a cracked rad available to me. I'LL pay shipping and do acomplete report on the job.
THANKS/

 

A sad day for another Hummer H3. My 2007 is at the GM dealer until Tuesday when he expects the new radiator in. I have 51,000+ miles on it and it has been babied all the way. Thankfully when I bought it 3 years ago I started reading Hummer stuff online and came across this forum and saw all the posts about broken radiators. Looked at mine at the time and ground the offending frame member back a bit so it didn't keep increasing the groove in the support post. When I got it, a fatigue mark was noticeable about 6-8" long on the right front of the angled part of the radiator. I watched it a lot. 3 days ago I was out and when I returned I smelled the smell of radiator death. Looking under the hood I had a crack clearly visible in that fatigued area and it was blowing Dexcool all over the engine. I had it towed to the dealer (40 miles away). Thankfully I have a bumper to bumper extended warranty that some said I was crazy to buy that covers everything except the replacement Dexcool (per the conversation with the Dealer). I'm glad I went for it. I placed a printer label just above it with arrows to the crack and told the Dealer don't even mention a diagnostic fee. He didn't.
This really should be a recall item, acknowledged by GM as it's clearly their fault no matter what the mileage when they keep on breaking in the same place.
Dave

 

I'll try and see if I can get my leaking radiator back when they swap it out Wednesday. I'm gonna try and get the dealership to hold open the work order since I have a GM claim submitted and if not settled by then so they may want to keep the radiator. If claim is settled or denied by then I will demand the radiator back to have to hopefully show the difference between the original one and the new one for I hear the new ones have been re-designed to correct this design flaw.

 

Here are the pictures I took, with some very newbie-styled literature to go with it. I'm not a mechanic and this was my first time ever doing anything other than brakes, tires, oil changes on my H3. The tools I used was a thin flathead, vise grips, 10mm and 13mm wrench, and a small phillips screwdriver. I went entirely off of previous user's instructions and I thank you all for that guidance. I'm posting these pictures in hopes that it will help aid other newbie mechanics such as myself, since i'm assuming the older H3's will be having this issue more often.

 

Here are more pictures with info regarding the radiator replacement.