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Hummer H3For the Hummer driver who wants the rugged look and off road capabilities of the Hummer, but in a smaller size and with a more fuel economy friendly engine.
I topped off my reservoir, but after some time coolant level tends to drop a bit. Doesn't bother me, but makes me wonder, where's it going?
Pressurised the system to 15psi via radiator, went around and found absolutely no leaks. Went back up and gauge was still at 15psi. Waited about 20min and still held 15psi. Oil analysis also came back clean so I don't suspect head gasket.
I understand the reservoir is not a sealed system, is it evaporating?
quote- I topped off my reservoir, but after some time coolant level tends to drop a bit. Doesn't bother me, but makes me wonder, where's it going? -quote
I presume urgent testing when cold?
Problem is if system has Crack that only shows with truck at operating levels you'll never know. Put some u.v. dye in and then test with black light.
quote- I topped off my reservoir, but after some time coolant level tends to drop a bit. Doesn't bother me, but makes me wonder, where's it going? -quote
Has your H3 ever overheated?
overheated, not that I am aware of. It ran hot when I first got it almost a year ago, but that issue has been resolved.
Originally Posted by Happy Hummer
I presume urgent testing when cold?
Problem is if system has Crack that only shows with truck at operating levels you'll never know. Put some u.v. dye in and then test with black light.
yes tested when cold, I've also tested for combustion gases. I'll try the dye method and see if I find anything.
If the system had a crack somewhere, wouldn't I see pressure drop? What baffles me is that it holds steady 15psi - why I am at a loss.
Originally Posted by Doc Olds
Check your Transmission Fluid for coolant contamination. How does the coolant look?
I have an external transmission cooler.
Does DEXCOOL not evaporate?
Last edited by MadDogBimmer89; Jun 21, 2024 at 10:42 AM.
Not when sealed! Properly sealed radiator cap & reservoir cap prevents evaporation. Btw, my 3 had a coolant loss 2x in the last 12yrs, only at operating temperature.
#1-12yrs ago I found hairline crack in the upper radiator tank, replaced radiator with aftermarket and still sealed.
#2-2yrs ago I found coolant loss at the water pump weep hole, replaced pump with aftermarket and still sealed.
Bottom line, you have a coolant leak.
Edit: I just checked my reservoir still at the FULL COLD level @96°F Ambient, and there's condensation inside under the cap.
Seriously where's the coolant going?
