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Radiator and tranny cooler questions.

Hummer H3 For the Hummer driver who wants the rugged look and off road capabilities of the Hummer, but in a smaller size and with a more fuel economy friendly engine.

Radiator and tranny cooler questions.

  #1  
Old 02-09-2019, 09:42 PM
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Default Radiator and tranny cooler questions.

Did hummer ever do anything about the transmission and coolant mixing and taking out the tranny? I have a 2010 alpha, is it prone to this failure or did they fix it after a certain year? I've been thinking about this lately and have been wondering about bypassing the stock integrated cooler and just running an external cooler.

Are there any issues with just running an external cooler, any transmission overheating problems with low speed wheeling? I read somewhere that on allison transmissions the external cooler only works at speeds over 35mph and that the integrated cooler provides cooling at speeds lower than that. Is the 4l60e in the h3 the same?
 
  #2  
Old 02-10-2019, 01:09 AM
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Nothing was done by GM to address this problem. If you have mileage on your radiator, its only a matter of time. Some people get lucky and the radiator ends up leaking so they replace it before the mixing happens.
You can always run a trans cooler with a dedicated fan such as the derale unit. It will be good for low speed if that worries you.
 
  #3  
Old 02-15-2019, 12:29 PM
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I would be more worried about an asteroid strike than a radiator failure swapping coolant into the transmission. Sure... it can happen in any vehicle brand that runs AT fluid through a radiator loop, but with millions of vehicles out there with that feature for decades the failure rate is minuscule.

No the 4L60E in an H3 is not like an Allison.
 
  #4  
Old 02-15-2019, 01:19 PM
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The radiator issue did happen to my H3 and ruined my transmission. It is true that many cars and trucks run this same setup but I feel like from the H3's design they are far more prone to it. The radiator rubs and gets cracked. It doesn't really cost that much to do the bypass with a trans cooler if you were going to constantly worry about it.
 
  #5  
Old 02-17-2019, 02:35 PM
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Originally Posted by Doc Olds View Post
I would be more worried about an asteroid strike than a radiator failure swapping coolant into the transmission. Sure... it can happen in any vehicle brand that runs AT fluid through a radiator loop, but with millions of vehicles out there with that feature for decades the failure rate is minuscule.

No the 4L60E in an H3 is not like an Allison.
Well there is at least one guy who had to do a 6l80e swap into his H3 and document it just because his radiator failed internally causing the trans fluid to mix with coolant and destroy his trans. Does it happen alot? Maybe not. To be honest I had 3 oem radiators fail less than 40K miles each so I guess I wasnt lucky to have a radiator long enough to find out...
 
  #6  
Old Yesterday, 02:46 PM
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A radiator leak causing coolant to leak onto the ground is different than the transmission cooler line loop failing inside the radiator allowing fluids to interchange.

Sure, a bunch of H3 radiators have leaked because the poor quality Asian core attached to cheap plastic tanks (plastic can crack, wear through, the core can become unattached from the plastic tank or the core itself can fail). All of which could happen and have nothing to do with the radiator cooling loop. I am on my fourth, but there has been no cross contamination on any of them.
 
  #7  
Old Yesterday, 03:38 PM
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Originally Posted by Doc Olds View Post
A radiator leak causing coolant to leak onto the ground is different than the transmission cooler line loop failing inside the radiator allowing fluids to interchange.

Sure, a bunch of H3 radiators have leaked because the poor quality Asian core attached to cheap plastic tanks (plastic can crack, wear through, the core can become unattached from the plastic tank or the core itself can fail). All of which could happen and have nothing to do with the radiator cooling loop. I am on my fourth, but there has been no cross contamination on any of them.
I don't know entirely how it happened in my situation, but my radiator was both cracked on top and internally (causing the coolant + trans mix)
All I know is that the problem did happen to me, and it sucked. I got stranded and it cost a few grand to fix
 
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