First time posting but I have been trolling for awhile during and after my search. Today I flushed my trans and when I removed the bung for the tc located in the upper right radiator coolant leaked out. I inserted plastic tube into bung and reinstalled it and began to flush it and I was getting trans fluid and coolant. It doesn’t seem right to me but maybe others have a better understanding than I do. I searched threads but didn’t find anything but failed tc in radiator and I really hope that’s not the case. I’m at almost 28k miles now and I wanted to replace the pan with a mag Hytec and thought it was a great time to see what’s going on in there. Any help will be appreciated!

 

You need to bypass the radiators internal transcooler and then install your new pan and proceed to do another flush and hope you caught it in time.

 

Calif Phil is 100000000% correct!!
Not that I ever doubt him

These trucks sadly are known for having the transcooler and the radiator sharing the same front coil assembly. The end caps are prone to crack and in turn leaks coolant into the trans and then that causes the transmission to lock up.
For about 100-150 bucks, you do the do the cooler bypass and insure yourself from a 3000-4000 dollar fix.

 

Yes. Sadly, this happened to my H3 and destroyed my transmission. On my H2 I preemptively went ahead and installed an external trans cooler to prevent it from happening to me twice.

 

so my radiator/ tc has failed? I was hoping that when the bung is installed that it seals it off. I noticed that it has an O-ring that seals against the radiator and then it has a flare and I thought the flare was to seal the tc and the o-ring was for the coolant? I will look into the tc bypass and do my research. Thank you for all your replies and I would like to have a better understanding of what happens to the oil cooler when you do the tc bypass?

 

Update, I was doing some searching on our forum and online and I ordered the tru cool 40k with the thermal bypass. I will replace the radiator also. I just don’t want tranny problems and I believe I caught it as soon as it happened. I checked the fluid and it’s still looks great on the dipstick but I will probably flush it again just Incase.. I looked at a Ron Davis Direct fit radiator and even had a conversation with him about it. It was like 1,250 but I liked the fact that you can just plug n play...

 

So my cooler has shipped and I will be removing my radiator and sending it to Be Cool so they can copy it and it will have oil and transmission cooler in it. I have all the bumpers and trim at paint shop and while I was removing everything I discovered it had a leaking input shaft on the steering box so I removed it and had it rebuilt and reinstalled it. It’s been a really bad week for my H2! I was going to have gears changed but it will have to wait a few weeks because it will be down as long as it takes be cool to make it and ship it... they make a radiator for a 2004 but I guess the 07 has a 34” core and maybe mounting locations might be different.

 

I pulled the radiator out this morning and it wasn’t too bad. I was able to tilt it back and remove it without removing the top of the core support, I was reading that OP had to to get it out and I might when I put the new larger one back in. I will box it up and ship it to Be Cool so they can copy it. I was amazed at how small the core was. I should have bumpers and all my plastics done on Thursday. I will have plenty to do while waiting for my radiator to be fabed.