I just purchased a 2009 H3 with an auto transmssion today. I sold my 2006 5 speed which always seemed to run hot.

I am in Phoenix and tow a flatbed trailer with ATV's on it so I was thinking it might be a good idea to install a transmission cooler on the new H3.

I got the tow package on my new H3. Does it come with a Tranmission cooler?

Are there any aftermarket transmission cooler recommendations out there?

Thanks~

 

I have a 07 with the tow package. The dealer told me there is no trans cooler needed and no difference in the radiator or transmission cooler with or without the tow package. Only the hitch and wiring harness are different.
I am assuming the tow ratings are low enough that the H3 is not modified for additional cooling with or without the tow package. I have looked all over mine for any trans cooler and there is none, other than the standard cooling lines from the transmission to the radiator like all other vehicles have.

 

The transmission cooler is inside the radiator. There have been a few reports lately of these coolers failing and causing transmission failure as the coolant gets into the transmission. The fix is to add an aftermarket trans cooler and seal off the transmission cooler connector on the outside of the radiator.

 

I would almost guarantee this would void the factory warranty, for at least the transmission. The dealer would have no way of knowing if the aftermarket cooler was better than the factory installed one inside the radiator. On the other hand adding an additional transmission cooler inline might be ok, but I would check with the dealer on this. Even though there have been a few problems with water getting into the transmission we can't all modify our Hummers as if everything that happens will happen to all H3's. I did purchase the factory GM extended 100,000 mile 7 year bumper to bumper warranty, and would highly recommend this for anyone who's existing standard warranty has not expired. You can purchase this through any GM dealer.

 

It might void the warranty, but I am out of warranty and decided not to go with an extended one. I will likely add an after market trans cooler at some point. But for now, I'll make sure that I change the coolant regularly to prevent gunk from building up in their potentially causing a failure.