Hold on guys I want to answer everyone. My problem with this installation is the rubber hose that PARTSOURCE sold me. They gave me 5/16'' fuel line with a 7.5mm opening... What it should have been as 3/8'' FUEL INJECTION TUBING WITH A 257 Farenheit rating, 9.5mm opening.
I also bought compression fittings today.
I took it on the HWY today and the trans temp went up very quickly but stayed at 165 to 175F. I'm thinking the reduced size tubing is restricting the flow that's why it's so high. I would like to see 150F ?

I would like to see my Trans Temp at 150F every day. That was not the case today when I took it on the HWY. The Trans Temp max'd out at 175F. I'm scared to drive it too much due to the fact the auto store sold me the wrong size hose. I'll change the hoses to a slightly bigger diameter tomorrow and see if my Temp goes down.

You should of used the largest barb, that came with the cooler, and didn't the cooler come with hose, you need trans/oil line, not fuel line....

How did you connect the hose to lines, did you flare the lines, or at least use compression fittings, that what i did..

Also, the cooler should keep the temp around 125, in the city or highway...

liveinxs,could you link me to your post. I looked for it but could not find it.
The cooler did come with a 4' length of the rubber hose but I used 2' of it to cap off the rad lines.
I did not flear or used compression fittings just slid the fuel line onto the trans lines. I bought 2 compression fittings that I would install today, as for the 3/8'' FUEL INJECTION TUBING WITH A 257 Farenheit rating, 9.5mm opening the parts store told me that is what they normaly use. I cant find 3/8'' transmission tube.
If after I install the bigger 3/8'' tube with the 9.5mm opening and still get a Trans Temp of 175F I would bypass / remove the REMOTE THERMAL BYPASS and see if that is restricting the flow .

Heres the link

https://www.hummerforums.com/forum/h...-34873/page18/

I made my own compression fittings, just go to home depot, and find the parts to build them, but you MUST AT LEAST FLARE the lines, will prevent hose from popping off lines.

As far as the hose you used, i don't recommend it, go on amazon and order the right hose, just search for it...

I did not use the thermal bypass, i have read several negative things about it, toss it in the garbage..

Also, are you sure you topped off the fluid, after the mod, as you will be low on fluid, since the cooler is much larger then the oem one..

You would of had to put at least one quart of fluid in the trans, plus who knows how much you lost doing the install..

You do know how to CORRECTLY, check the trans fluid, the hummer has to be running...

I did not top up the fluid as yet. I know about the engine running to check it.

I may need to leave the REMOTE THERMAL BYPASS due to the very cold winters here in Canada.
Someone was saying that it would take forever for the transmission flued to warm up without it during winter seeing that its not rigged into the rad anymore.

I read that the external bypass doesn't open fully until about 180 degrees, not sure exactly but ill bet if you eliminated that youd run 125 to 150 all the time

if you could find out what true cool says their bypass opens at you will know if that's it, not sure if you can call or email them