Thermostat '04 H2

[ptownhummer]

Noticed heat does not work except when engine speed reaches 40 mph or above. H2 now is overheating at idle but quickly cools at high rpms. I'm thinking thermostat needs replacing? Where is the thermostat located and is it easy to replace? I can't find a service manual to reference for help.

[OrangeCrush]

Noticed heat does not work except when engine speed reaches 40 mph or above. H2 now is overheating at idle but quickly cools at high rpms. I'm thinking thermostat needs replacing? Where is the thermostat located and is it easy to replace? I can't find a service manual to reference for help.

Follow the lower radiator hose to the housing on the waterpump. The housing sits sideways into the front, not on top like other vehicles. It sits directly below the idler pulley for the serpentine belt.

Anyway, it's extremely easy to change but before you do that, make sure you are full of antifreeze.

I'd hate for you to change it out and find out you are just low on antifreeze.

HTH's,

Mark

PS. Check your clutch fan too.

PSS. Welcome to the forum.

[ptownhummer]

I already bought the Thermostat, i just can't figure out if it's as simple as removing the end of the large hose or if I need to remove the front of the housing? Also, I noticed yesterday that I had a small amount of fluid under the front end. It didn't appear to be coming from any of the hoses, looking under the vehicle it appeared to be running down the passenger side of the engine block down the side of the transfer case and oil pan. Is it possible the water pump may be bad? Thanks for any help. Hope to post some photos of the H2 soon.

'04 Hummer H2
6" fabtech
Mickey Thompson ATZ 36x15.50x20
20x12 Dick Cepek DC-1

[Dustyzz]

Sounds like the seals in your water pump are gone and your getting anti freeze leaking from the weep hole on the water pump housing.

YMMV,
/dusty

[vandy0090]

hey buddy i had the same issue with mine right after i bought it. get going down the freeway with some rpms to her and the heat would kick on and the temp gauge would go down.. stop at a light and the temp gauge would come up and it would start blowing cold. thermostat is your issue. its the front center twords the top of your block. i belive it was 2 bolts to take the housing off. not hard at all. the new one sits in the housing really well (not like some fords i have) so its easy to align when reinstalling. as far as the occasional fuild under the truck.. let me know if u see anything. i also am gettin that and it started about the same time as the first issue. i was thinking maybe blew out a seal on my water pump. maybe (hopefully) a bad hose. but i hanvt had time to pull the scrape plate and take a look. i cant seem to find anyhting from the top and its beel tricky since it only shows up once a week or so.. but good luck:beerchug:

[03h2gm]

had the same leak problem with my 03h2, and it was just the water pump seal cost me $19 to re-place. Hope this would help.