Hi everyone, I'm a relatively new Hummer owner, I picked up my 2007 H3 last October and so far it has been rock solid and I travel extensively professionally. Because I travel so much, I religiously check the fluids/belts/hoses on a regular basis.
It has been running a tad hot as of the last 2 weeks or so just a hair above the halfway point on the standard coolant temp gauge. I topped off the reservoir tank and it seemed to return to normal. Last night it started running hot on the turnpike, I turned the A/C off, cranked the heater up all the way and it brought the temp down enough for me to make it off the turnpike safely, when I get it parked and open the hood, there is antifreeze everywhere and actively leaking from the bottom of the engine compartment. The hoses appear to be solid, but I would probably replace them anyways (she has 186K miles) the radiator also appears solid, which would leave the water pump. I do notice some play in the fan shaft so I'm betting the water pump is shot.

FWIW I have always done my own vehicle repairs, short of transmission work. And I've rebuilt a few camaros, having to spend a lot of time on cooling issues I know all of the components in play:

Radiator, fan, fan clutch, water pump, serpentine belt, thermostat and hoses.

My question is...am I overlooking a Hummer specific component?

If I do replace the water pump should I replace the thermostat as well?

Any input would be greatly appreciated. I've been scouring the forums and the great google & youtube.

Thanks in advance!

Christian

 

My .02. My H3 was never coming fully up to temperature. It also had an annoying vibration/noise just off idle. I too had some play in the water pump shaft.

Water pump and fan clutch seem to go out just about simultaneously. Seems that if the water pump shaft bearings get loose, it tends to aggravate the fan clutch and it will go bad soon after. To get the water pump off, you already have the fan clutch in your hands, remove 4 bolts on the fan clutch to swap a new one onto the fan. That fixed the noise/vibration.

The thermostat has one end of the lower hose on it. So after you remove that end of the hose from the thermostat, you're only one step away from removing the thermostat itself if you're going in through the wheel well. Might as well replace it while you're in there. That fixed the low temp readings on mine. My water temp gauge now seldom moves from just above halfway. I used the 195 degree OEM stat.

Finished the job with a new tensioner, idler pulley, pressure cap, and fresh coolant.

 

Hello and welcome to HF.

More than likely, you have the oh so common radiator leak. This is what happens when GM sourced Asian crap radiators, the plastic tanks can separate top or bottom, or perhaps just as commonly, the top radiator mount bracket rubs the plastic top tank and eventually cracks or wears through it.

You can search around for threads on this, there are a ton. Here is a link to the over the top blah blah blah thread damn near everybody and there brother has posted in. https://www.hummerforums.com/forum/h...-leaked-21184/

There are better and more useful threads on the topic, but you get the idea.

Rinse it off under the hood, let it dry, then start the engine and let it reach full operating temp, and see where it is spitting..

BTW a tad over 1/2 on the dash gauge is NOT running hot. Look at this old thread for the short and simple. https://www.hummerforums.com/forum/h...erature-28381/

 

I looked at it this way, as soon as mine goes, it gets replaced with a quality all aluminum radiator, and it did.

Thank you CFS.

 

BTW a tad over 1/2 on the dash gauge is NOT running hot.

I realize that it wasn't necessarily running "hot", but if for the last 6 months of daily use it has stayed *exactly* on the middle of the gauge...any deviation is running a "tad" hot(hotter than usual) in my perception.

I've spent a day doing the research and you sir...have given me the best start in the right direction with this advice:

Rinse it off under the hood, let it dry, then start the engine and let it reach full operating temp, and see where it is spitting..

That's exactly kind of input I was looking for.

Thank you!

Christian

 

exactly the feedback I was looking for...

Thank you!

 

I just filled the radiator with water and I didn't even have to start it, it started dripping on the engine side immediately...sooo, I'm off to the parts store for a new water pump. While I'm in there I'm going to replace anything expendable(thermostat, both hoses, the belt and the fan clutch) just because the truck is relatively new to me and I'd just as soon not have to tear into the cooling system again for a while.

Thanks for all of the input!

 

Might want to rent their Fan Clutch Nut Wrench, makes things much easier.

Good luck.

 

It's on the list!

Thanks again Doc, good karma brotha

 

Hi everyone, Just an update for those facing this endeavor in the future. What a bear! I had to go through 3 sets of the super-special-fan clutch wrench sets (from each of the popular parts stores), to find one that actually fit. Even though the tools have 36mm stamped on the tool in actuality it was more like 40mm(wear and tear). Anywho, once I got a relatively new set, it fit as it was supposed to and from there it was a downhill race.

Quick recap on the timeline:
1.5 days research.
30 mins to diagnose the real issue(water pump).
2 days to find the right tool.
90 mins to swap out the water pump.

The Black Pearl is now back on the road and running cool as a cucumber

Thanks again to Doc Olds and Cucumber1949 for your input!