I joined Hummer Forum when I bought a 2010 Hummer H3t in 2016 and noticed many posts about the radiator problem going back to 2007 + models.
Here I am at 90,000 miles, the radiator has a crack exactly like the many mentioned here, a 2 inch horizontal crack at the top right of the radiator
GM has the ‘authorized’ supplier of this junk radiator ACDelco which has apparently cornered the spare parts market for GM.
As a virtual captive market, I am buying a replacement of this known sure-fail product. I think it should be supplied free-of -charge until the manufacturer has solved the problem

 

Welcome to HF.

ACDelco is GMs parts supplier and has been so for ever. They are owned by GM. Other manufacturers make replacement parts for GM vehicles so not sure how ACDelco cornered the market???

You have a basically 10 year old truck, chit breaks and happens. When your warranty is over, it is over. I get the frustration. My 07s radiator went at like 75K miles. I replaced that with a $500 CSF aluminum radiator. That CSF started leaking 3 months after I replaced it. They sent me a replacement under their "lifetime" warranty. I kept the first CSF and took it to my local performance radiator shop (also my Mother's neighbor) and he repaired it for me.

Two years later, the CSF replacement started leaking, I could smell it for 6-8 weeks before that but it did not drip on the ground at first. Contacted CSF, provided pics of leak and serial #. They said their "lifetime" warranty only applies to the first one I paid for, not the replacement. Had to swap in the first CSF that was repaired for the replacement leaker. Shortly thereafter I sold the 07. I now have an 09 w/ OEM radiator. Taking the replacement CSF to my local radiator guy again to be fixed for a backup when the 09 leaks, because some day it will.

Do some searching here, there are threads on the topic, different replacements used and results. That may help.

 

Come on Peter, Sounds like you just wanted to complain about something.
You couldn't have looked very hard for a replacement radiator.
There are many different suppliers of aftermarket radiators and even a few high performance all aluminum units out here too.

 

Hi Doc, Tainter,
It’s a nuisance dealing with ‘planned’, obsolescence for the servicing industry.
i did look at a number of alternate brands , I nearly bought the aluminum one made in China but the welding looked suspect .
Without looking over the real thing in my hand, I decided to go for the ACDelco. The actual work would have been the same, messy.
..Having done the work now and topping up the transmission fluid ( and it was messy because one of the inserts to the cooler popped out losing some 2+quarts).
I now have gear shifting problem - hopefully due to needing more fluid but not overfilling it.
More transmission fluid ( code: 88865601 full synthetic),is on order and I hope to report problem fixed later this week.

 

UPDATE:

i added more transmission fluid in the cold condition 2oz and checked the dipstick a few times
The dipstick has a level for cold and about 3/4 inch up - a hatched area for hot, (that is, while the engine idles and the vehicle on level ground).

Now comes the mystery. When the engines is running hot, the fluid drops to barely touching the tip of the dipstick. When it’s cold, I find the fluid reaching the lower edge of the hot hatched marker. Are the markers on the dipstick reversed ?

The good news is , by adding another 2 oz of fluid, the gear shift problem has disappeared, presumably oil pressure is within reach.
As for the apparent reverse reading on the dipstick, my guess is when hot , the transmission oil tank expands which explains the drop of oil level on the dipstick.
I stand corrected; can’t imagine GM not spotting it after so many years

 

There's really no mystery if you check your transmission fluid:

ENGINE RUNNING AT OPERATING TEMPERATURE!

check not running, will show high on the indicator
check running & cold, will show low on the indicator
check running at operating temperature, will show the proper level.

 

There’s the rub, Hummerez,
When hot the oil just touches the tip end of the dipstick
When cold the level reaches the bottom edge of the ‘hot hatched’ area.
for those curious about the physics, i’ll Appreciate your deliberation.

 

None of that matters because you only check AT fluid with the vehicle on a level surface, engine running at full operating temp. Checking before/after with the engine off is not how it's done.

 

Hi Doc Olds,
I take your point since the transmission operates in operating temperature, at which, oil level should be checked
In which case, the T-fluid level is way down , just touching the tip of the dipstick.
And, I have just done 40 miles at this ‘low’ oil level though gear shifting was normal. Oops.

Would you do me a favor Doc; any other interested member: What’s on your dipstick and what oil levels do you.


PS: I found on a different hummer website, a similar situation: The trans. tube popped out of the radiator cooler, lost fluid. And the comments matched yours: Check level when engine is hot ; wheels on level ground. So its pointless having a cold level marker on the dipstick; only to confuse the Hummer novice.
perhaps the procedure should be that when filling the trans fill up so as to see oil at least to the cold level mark before starting/warming up the engine to operating temperature.Then on idling top up to the hot hatched, marker.

in conclusion, after owning a Merc E420 with everything failing but the engine, I have found the Hummer much more serviceable for DIY, despite the radiator, widely known to crack at the same spot but having done the replacement, it’s quite serviceable.
The mere fact that one could slide under the truck without jacking it up makes for checking derusting and spot spraying rusted/treated spots ‘down under’.
i have also replaced the oil drain plug with one that has a release valve and have the parts now to relocate the oil filter for better reach and to add another fine particle filter for cleaner oil.
i have also changed the front brakes and drum. After-market parts are easy to get, cheaper by far from the merc. And my Luxury model gives me the same leather seat comfort .

hang on to your H3 as it is going to be a collectors’ vintage.

 

The cold check marks are really just for an initial fill so that the trans can safely be brought up to proper operating temps and then a final fill can be done. That is pretty much standard on all full size GM trucks and SUV's and certain mid size ones. Not sure on others as I've not had much personal experience with other models though.

Per the GM eSI system..... "Use the cold check procedure only as a reference to determine if the transmission has enough fluid to be operated safely until a hot check procedure can be made."

Attached doc....