Ok. So I did the radiator bypass for the transmission cooler. It has been some time and suddenly I see an intermittant low coolant message on my display. I get around to filling up the resevoir. So stupid me (or stupid Hummer depending on which way you look at it) couldnt read the writing on the side of the resevoir that is blocked by hoses and facing towards the drivers side.... and I fill the whole resevoir up.
Ok.... After that I ran a few emergency med calls this weekend (which if you dont realize I do emergency fire medic for my fire dept - among other things... and I use my own vehicle) which means quick start up quick take off (well as quick as a H2 can take off) and then running down the road at speed and driving it a bit hard til I get to the destination, which usually then is a quick shut down and a run into the house.....

So here is the weird help thing.
I get done.... I dont remember seeing any coolant leaking after the runs, but then again I didnt look. The next day.... casual day to take my daughter to school. pull back into my house.... leaking quite a bit from the passengers side. Almost a drip a second. The resevoir which I filled 2 days earlier is half or better gone.
Ok, so me and my friend look through it this weekend short of pulling everything apart (we did remove the skid plate). Couldnt really see anything other than everything was covered in dex-cool. Ok we ran it for a while. i brought it up to 3k and kept it up there for a few minutes and no dripping. the temp gauge is showing 190ish (no over heating). No lights no warnings. He cant see a drip. So we kill it and of course now we see the resevoir has gone up quite a bit. So we figure the system pressurized and it over flowed. Ok so I figure it had to just be an overflow so today I drive it over to the local post office. About a 15 minute drive in stop and go traffic. I get out and I dont see anything. I got to walmart and still nothing, but I come back and I see a leak.... this time it isnt on the passengers side but instead on the drivers side. HUH?? Same size same one drip per second. So I cant figure out what is going on. Of course I know I need to get in and see more clearly, but any idea? I mean a leak that switches sides? Anyone have any ideas since of course the platform the radiator sits on blocks the view and such

Thanks

 

Water pump or water pump gasket is what I would guess. You need to get it pressure tested.

 

Ok, the newest piece to the puzzle so far is it seems I can drive around all day long without any sign of leaking .... as long as I dont shut the truck off ... as long as the system is running basically the truck doesnt leak.

As soon as I shut her down, then I get that drip drip drip going on
Again still no lights on the dash, still no temp on the gauges over 190-200ish, given I still havent had a chance to spray down the underneath from the overflow from the other day (but come on, its been almost 5 days now and theres been 1 good rain storm and alot of 95+ days too - it shouldnt be dripping this bad from that over flow)

Any ideas?

 

That is a classic symptom of a water pump leaking.

 

Yeah, sounds like waterpump.

 

Ok, here is the latest.
I was working on it in the dark with a light, and because of the light I was able to see what appears to be about a 4 inch micro crack on the left side (same side leaking)

So I order up an aluminum radiator repacement. Went in real nice....
Fill everything back up, go to drive it around... cooling is fine.
Park it, turn it off... out the coolant drips again.
UGH! I look and sure enough the main hose (the top hose) is dripping now. I squeeze the hose and it pours out....
Guess I also developed a leak there too
Replaced the hose, and now I am waiting to see how it is.
(ordered an airaid pipe, and waiting on that to come in before I put her all together and run it)

 

Some parts stores will loan out radiator pressure testers. That might help you a lot in your diagnosis.

 

HOw many miles on the truck .. Is common for the Water pump to fail around 100k .... I will check it or replace it as well as the hoses ..

Replacement is not 10 min but not a PIA either ... The harder part was to remove the cooling fan .

Amazon had the parts cheaper than any1 .. also make sure to get the thermostat