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, 08:42 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, 12:09 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, 11:29 AM
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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.
 
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Old 02-15-2019, 12:19 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, 01:35 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...
 
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Old 02-18-2019, 01:46 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.
 
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Old 02-18-2019, 02:38 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
 
  #8  
Old 02-22-2019, 02:00 AM
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The other day my 08 Alpha was idling in 80*F weather okay, but when I turned on the A/C, the temperature started to creep up. Not only on the temperature gauge in the IC, but also the ambient temperature readout on the rear view mirror. The readout went to 104* after a few minutes. Where is the probe for that located on the vehicle? Is it close to the radiator?
So I need to address this "overheating" issue. Has anyone installed a Ron Davis or CSF radiator? Did it solve the overheating issue, and are they good quality? Would installing a radiator fan in front of the OEM radiator solve the problem?
My brother had to repair his transmission in his Pathfinder when the tranny loop in the radiator corroded; I want to avoid that. Is there any GM OEM tranny cooler available from a Chevy truck that could be adapted to the H3 tranny cooler lines?
 
  #9  
Old 02-22-2019, 08:25 AM
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1) Be sure you have a good fan clutch. 2) Use a fresh/clean DEXCOOL mix. 3) Keep the "outside" of your radiator free of debris , mud etc. . 4) If you add the proper amount of PURPLE ICE, you will have zero corrosion and the coolant temp will remain measurably lower. 5) If you don't have the foam seal across the front of the top tank, add one. It ensures air flows through the radiator and not over it. Some H3's were shipped with the seal and some weren't. The GM # 15806298.
Where I live, it is not unusual for the summer ambient temperature to exceed 100. I have had zero problems on the trail or in stop and go traffic with either of my H3's. Also, both have the original radiators. I did use a dremmel to trim the tab that so often damages the front of the upper radiator tank.
 

Last edited by Ordieh; 02-22-2019 at 08:37 AM.
  #10  
Old 02-22-2019, 11:21 AM
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Originally Posted by Coolvibes View Post
The other day my 08 Alpha was idling in 80*F weather okay, but when I turned on the A/C, the temperature started to creep up. Not only on the temperature gauge in the IC, but also the ambient temperature readout on the rear view mirror. The readout went to 104* after a few minutes. Where is the probe for that located on the vehicle? Is it close to the radiator?
So I need to address this "overheating" issue. Has anyone installed a Ron Davis or CSF radiator? Did it solve the overheating issue, and are they good quality? Would installing a radiator fan in front of the OEM radiator solve the problem?
My brother had to repair his transmission in his Pathfinder when the tranny loop in the radiator corroded; I want to avoid that. Is there any GM OEM tranny cooler available from a Chevy truck that could be adapted to the H3 tranny cooler lines?
Your temperature started to creep up to what? Looking at the dash temp gauge is like looking at an idiot light with a needle. The only what to tell what the actual coolant temp is = using a scan gauge/tool to read it from the PCM. 3/4 on the dash temp gauge is not overheating, not even close. Overheating is when the needle is in the red.

When an H3 gets hot it will let you know in the DIC. Let's review the three layers of H3 overheat protection: The H3 will first shut off the A/C if it was on and display "AC OFF" in the DIC; then if temp still rises, display "ENG HOT" in the DIC and chime (ding, ding, ding); then if temp does not fall, go into Reduced Power, all before reaching an actual overheat situation at 260F +.

If you never saw any of those messages, not too hot and not an overheat.

Yes I have a CSF radiator in my 07 after the OEM factory radiator took a dump. It cools very well, but I am on #2+ now. The first CSF leaked like crazy after three months. I made a warranty claim, they sent a new one which I installed day after Xmas 2016. Took the leaker to a local shop (Superior Radiator) and had it fixed for a back up. The #2 started leaking/dripping on the ground January this year. It started to smell when idling or just after shut down about 6 months before dripping. I made another warranty claim. CSF said the original purchase radiator had a lifetime warranty, but the replacement was only good for 2 years and they refused to send a second replacement. WTF? BS!

I swapped in the repaired CSF last weekend, all is good so far. The #2 leaker will be going back to Superior Radiator to be fixed as a backup for my 09 Alpha.

What I learned per my neighbor at Superior Radiator (who BTW does use CSF radiators in some replacements with their custom variations) is that the H3 all aluminum CSF is a cheap Asian core that had aluminum tanks welded to it so it looks good, but it ain't no great shakes.

Go with a Ron Davis instead if you make a move.
 

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