Hi, my 03 has 91k miles and I can smell coolant after driving but everything looked OK until today when I saw some fluid on the hard lines coming out of the radiator, I think those are the Trans cooling lines. It is wet where the crimp is from the hard line to soft line. Also, noticed that it is wet right below the crimps on top of the brush guard (I think it is called that). I am going to do a radiator pressure test today or tomorrow to see what that tells me.
I am not too familiar with how the trans cooler on this works, my Ram Cummins has an external trans cooler so I will read up on that further.
My Wife normally drives this and doesn't know anything about cars and yesterday she told me that the info panel said 'coolant hot' so I noticed the tank was empty, I added a gallon of Dex-cool 50/50 and this morning I drove it on a test run and it now says coolant low and the temp was around 210.
Again, I do not see any coolant leaks anywhere and no drips underneath it either. I will post more info after the pressure test but wondering if anyone recognizes any symptoms here and can give me some idea of what to look for.
Thanks

 

If the coolant was empty then there's definitely a leak, maybe a slow one. When this happened to me I had to replace my radiator. The big issue you want to avoid is the trans fluid mixing with coolant, which will destroy your transmission. It happened to me on my H3. The first thing you should do is have an external trans cooler installed on your H2 before disaster strikes.

 

OK thanks. So I am guessing:
1-New Radiator (since it's almost at 100k)
2- Plug the trans Cooler lines on the new radiator
3- install trans cooler

Do you have a link(or Brand to search for) for a good Radiator and Trans cooler?

Thanks!!

 

I was Googling around and came upon this post. It shows that some Hummers had an External Tranny cooler from the factory and I have that on mine (I am the 2nd owner so not familiar with all of the options it has). Here is the post, if you scroll to the bottom it has a pic showing the factory cooler: https://www.elcovaforums.com/forums/...ad.php?t=42698

So what are the two hard lines coming out of the drivers side of the radiator, one on top and one on bottom? They lead from the radiator down to underneath the block where they are crimped to a soft line?
Thanks to any help!

 

Seafood, correct there is already an external tranny cooler, but the problem is that your tranny cooler lines still run through your radiator and then out to the external cooler. DexCool eats away at the internals of the radiator and allow for fluid mixtures. The only way to cure this is to remove the radiator from the equation all together, get yourself an external cooler and replace your radiator. I also recommend completely flushing out the DexCool and replace with regular green anti-freeze, it will take a few extra steps (pulling water pump, flushing heater core, etc), but it is worth it!

This is what I used, and it is perfect:
As for the lines coming out of the driver side of the radiator, those are your oil cooler lines, also built into the radiator. That is another reason to replace your radiator and flush all the DexCool, to prevent that side from rupturing internally. Or you could just get an external oil cooler as well, but that is less common.

 

OK, I think I have a better understanding of everything now except if you can help me a little more with the installation of that tranny cooler you linked to. Where does it mount and where do the hoses connect to, does that kit have everything I need? Thanks again!!

 

No worries, so the kit comes with everything you need to mount and install. I also replaced my radiator so I basically took everything out, radiator, ext trans cooler, disconnected all the lines. To mount the new cooler, I just drilled out the old cooler from the two brackets that were used to mount it, put the new cooler in place, lined up things making sure the hood closed cleared the cooler, then mounted it into place. I used the original brackets just as extra support and to ensure the bottom didn't move forward, as there isn't anything to mount into the bottom. You could probably rig up a bracket to connect the tabs to the original bracket, but i didn't do that. Then running the lines is straight forward, you will need to cut the lines, i did right before the hard lines ended, ran the rubber tubing into the heat-bypass, then into the cooler, back to the bypass, then to the other hard line. There is a specific flow you need to follow if you are going to use the bypass, I can take some pictures later today to give you the correct flow. Hooking into the cooler doesn't matter, so just one in and one out. This may help you see things a little better as well. https://www.hummerforums.com/forum/h...-cooler-35751/

Darren

 

Hey Darren, super appreciative of your reply.
I would like to see some pictures whenever you get a chance as plumbing in the new tranny cooler is where I am stuck, everything else seems straight forward after reading your replies.
Take care and again, whenever you have time.
Sean

 

 

I sent you an email last week, in case you didn't see it.
Thanks