My 2006 H2 with 100,000 miles just died because the transmission cooler inside the radiator leaked transmission fluid into my antifreeze.. The items
now replaced are transmission, trans cooler, water pump, all hoses, radiator,
thermostat,overflow bottle, etc..... I found a very nice all aluminum radiator from shepard autoparts for $150 that is a direct fitting unit and I dont want anyone else to go through this a_ _ pain. If it could happen to me then yours is no different. I serviced my cooling system regularly with 50/50 mix....

 

Just curious, were you using Dex-cool for your antifreeze?

 

Man, I have heard of a couple radiators letting go at a bit over 100K. Mine is a 100K exactly right now. Bought it used a year ago. I never got maintenance records so I don't know if the radiator was ever changed.

Is there a manufacture date on the radiator somewhere??????

Are other members proactively replacing radiators to avoid this. If I am correct, other GM trucks have this same radiator type and when I called the local GM dealer/repair shop...they said they have not performed many types of repairs due to the inner transmission cooler leaking into the radiator fluid or vise-versa.

So I am really unsure what to do. Suggestions? I am concerned over something that has a low chance of occurring? I feel for inputamech...but don't want to replace a radiator just for the hell of it either.

 

Yes I was always using Dexcool..... I figure $150 is cheap insurance to save
either your engine (because the oil cooler is in the left side) or your transmission (cooler in the right side).... I only mentioned it because it is
expensive and painful if this happens... I figure if a radiator went 100,000
miles it is worth changing anyway.... The rubber gaskets that seperate your
antifreeze and the transmission fluid get hard over time and wont last for ever.

 

I wouldn't say this is a common problem that happens to the 2's but it is well known. Most people will cap off the in radiator tranny cooler and just add a larger external cooler and be done with it. That is obviously before anything bad happens.

 

I guess that depends on what you mean by common. If it's an issue everyone is aware of in my book that makes it pretty common. I had to deal with it and the dealership did all my repairs and service. I was just driving down the highway and suddenly started to loose power. I limped to a chevy dealership and had to have my ride shipped 180 miles home to have exactly what the OP had to have done. It wasn't cheap and if it had been any other car I would have just sold it for scrap on the spot.

 

Well, I am back up and running.... I had a bearing in my transfer case that was making
metal so I rebuilt that as well... The worst part of the whole problem, besides the expense, is how do you get the transmission fluid/glycol sludge out of your engine??
I used Simple green cleaner. I diluted it as it says and flushed the engine 2 times then
rinsed 3 times with water (driving 20 miles in between) for you "Do it yourself types"
and it seemed to do the trick... Time will tell. Good Luck to All

 

I believe the radiator heat exchanger for the trans cooler lines is there to bring the trans fluid up to operating temps in colder areas and not to cool it. Living in the south, I don't need it. I can't remember off the top of my head whether I bypassed it on mine or my wife's, but will make sure to bypass it on the other one now. It's definitely worth the ounce of prevention. Especially since my radiator needs to be replaced due to coolant leaks. I also installed dual trans coolers on both H2's. Mine running 40" tires is harder on the tranny than normal even with gearing changed. After doing this, I was able to pull my trailer up the mountain passes and not even get to 150 degrees trans temps.

 

I spoke to a very good and trusted private mechanic. And they have certainly heard of this condition and said with 100K miles, it would be well worth the price to bypass the internal and install an external transmission cooler. I experience pretty cold winters...so they said they would mount the cooler up against the radiator so that some heat is still transferred on cold days. I am not sure why, but on cold days my tranny temp guage usually never even registers. On hot days it does.

I asked if I was just being paranoid about my radiator failing and ruining my tranny...they said they see it and a small investment now would save $3500 or more on a ruined tranny. Because you would not know the internal cooler failed until it was too late and the transmission would be ruined or contaminated.

So, I am getting an estimate as I don't really want do it myself and they know exactly what to do. When I was younger, I would not hesitate to do this myself...but as I get older....my time and energy is worth more to me. I have had this little worry in the back of my head about the radiator...so it will be good to put this worry to bed once and for all.

 

Here is a thought about just adding a transmission cooler and not replacing
the radiator... The engine oil runs through the left side of the radiator and
if that cooler fails you are rebuilding your engine.. Most people dont replace
the radiator until it fails but when the price is $150 for a radiator plus antifreeze you should be changing anyway at some point it seems to me to
be a no brainer... Thats why I started this thread... On the H2 changing the
radiator can easily be done in 2 hrs...