After reading all the issues about radiator cracking, I took a look at mine. First off, you need to pop the hood, remove the foam padding between the radiator and and the support member (just in front of the radiator cap) and do a visual inspection. I found mine to have some chaffing going on but it was light in nature. Looking closely at the cause, I determined that the radiator is too close to the fwd support member. There are two ways you can fix this, one, take a grinder and grind the aft lip on the member to gain more clearance or, two, remove the upper bracket and elongate the the mount bolt hole to gain more clearance. I chose method 2. The fix takes all of 10 minutes. After removing the bracket (it's held on with one 13mm bolt), I took it to my bench vise. Using an augering bit in my drill motor, I carefully ground the hole farther fwd. Effectively, I have added about 3/16" clearance. Before putting the bracket back on the radiator, I used door/window insulation foam with a sticky back and applied that to the entire length of the fwd side of the radiator. I also used some 1" pipe insulation to the member for added protection. When I reinstalled the bracket before fully tightening the bolt, I used some muscle and pushed the radiator aft while tightening with the other hand. I now have extra clearance to keep the radiator from chaffing the member and this should last forever. If you haven't checked your radiator for this issue, you should. Could be expensive if you let it go. That's my 2 cents for this problem.

 

Here's one last pic all put back together......

 

Good job and nice pics.
What about the bottom of the radiator ?
Does that also have a clearance issue ?
And does that also need your similar repair ?

 

Not everyone agrees that elongating the hole is a good idea.
See the previous discussion, posts 75 thru 80
https://www.hummerforums.com/forum/h...d-21184/page8/


That foam pad on yours was added by GM on later models as an attempt to correct this issue. My 07 doesn't have it.

 

I don't think that fixing the rubbing issue is the fixing the whole problem. I'm not convinced that the cracking is caused by rubbing on the crossmember. I think that the plastic is just weak and after many heat cycles it gets brittle and the 15psi radiator pressure is finally enough to bulge the tank and crack it (usually outboard of the center portion that is rubbing).

 

When my radiator went, it was all deformed on the top of the plastic and where it meets the aluminum itself. It was not a result of wear against anything, it was purely defect in the plastic.

 

I just meant I leaned slightly aft on so the newly elongated bracket would go where I wanted it. It still moves freely.

 

I have been under it several times and everything that I can see down there looks to have enought clearance.

 

Mine is an 06. It had the foam strip already installed and from the looks of it, it was original. This strip of foam was not intended as a chaffe strip as it is very course and crumbles just rubbing it. It appears to have been just an air gap filler so air gets sucked through the front of the radiator and not recirculated through the top. I used two layers of pretty dense foam. It should last but I have more if I need to replace it from time to time.

 

Did the slot whole method a few weeks ago and hope that it at least solves one issue.
If the plastic cracks because of aging...then nothing else then a new radiator helps!