After the exhaust manifolds get fixed next step is to see why transmission temperature sometimes reaches 225 to 230 degrees. Engine stay cool but slowly rises as trans gets hotter. Have change sender out, and added deep pan with some reduction but not enough. What is your normal and hottest operating temperature. Thanks

 

Up to 220 is usually fine. So your 225 -230 is sill within range.

 

i installed a 8 inch/12 volt, power fan on my cooler, i never see it go over 200...and it helps the rad with some of that Florida heat.....lol........just to be on the safe side anymore....it has the towing package,used to start climbing when hauling the boat,no more....

Have a great day....Rick

2004H2/2006H3

 

Mine normally stays around 90c to 98c the hottest.

 

did you install aftermarket tranny cooler yet?, bypass the radiator all together, installed tru cool on mine and I never get above 125ish.. read this
Tranny cooler installation - Hummer Forums by Elcova

 

Yes this is what I did and It has never been above 140, normally runs about 125.