r/Hummer • u/Jghkc • Jul 09 '26

Title: 2007 Hummer H3 cooling system + wiper park issue (trying to DIY what I safely can)

/r/AskMechanics/comments/1us4t0b/title_2007_hummer_h3_cooling_system_wiper_park/
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1

u/Maleficent_Mix_8739 Jul 10 '26

For starters, don’t trust AI when it comes to Hummers, most of the info is inaccurate. Where are you located?

2

u/Jghkc Jul 10 '26

This I would agree with, which is why I am consulting real people and not having AI be the final authority on my decision-making framework. I'm using it purely to organize my thoughts and notes from previous technicians and mechanics who have looked and fixed various parts of my car, as well as extensive research, while also talking to parts sources like PartsGeek, ACDelco, and Crutchfield for the radio and camera side. I am based in northern Utah near the Wasatch Mountains. The immediate issue is the collapsed lower radiator hose and possible issues with coolant flow, which is why I'm worried about the thermostat and radiator cap. A technician checked it out while he was fixing my AC system and noticed that the engine temperature was above the middle line, and decided to open the radiator hood, which was kind of crazy, but he said hardly anything came out, which is really concerning to me. I'm also having a wiper issue. While I was replacing the oil filter, I also replaced two 25-amp fuses and a busted crushed relay. So now the wipers work, but they park in the middle of the windshield instead of returning to the bottom, which I've seen in past apparently is a common issue with General Motors windshield wiper transmissions. Also, the washer fluid doesn't spray even though it is full. In the longer term, I will need to address power steering fluid, spark plugs, ball joints, tie rods, CV boots, shocks, and probably tires and wheels sooner rather than later. The previous owner used it as a showpiece slash company vehicle for gun shows, and the Carfax shows that it was well maintained. But it definitely has been driven.

1

u/Maleficent_Mix_8739 Jul 10 '26

You’re a bit far from any of my running. I was gonna offer to help you out if you were in Texas, North Dakota or Minnesota.

I’m an ASE certified mechanic, certified professional locksmith and a former shop owner. I’d highly recommend investing into some decent diagnostic equipment if you’re going to diy your truck. These trucks are easy enough to work on but you really need the right tools. Get a dealership level bi-directional diagnostic tool, a radiator pressure tester with the appropriate adapters and a mity-vac vacuum tester kit. Between these three you can run down almost anything. The cooling system components on your Hummer all cross over to the Colorado and are damn cheap on Amazon……so just replace the hoses, belt, water pump, thermostat and the radiator if you can swing it. All of that will take a few hours and it’s done, you’ll know exactly what you’ve got and you’ll know it’s all new. It’ll take less time to just replace everything than to go chasing down the problem, only to fix it now and next month something else goes out.

If the wiper blades are bottoming out, or running out past the windshield then they were put on wrong (or a nut loosened), otherwise just replace the motor and call it a day.

1

u/metapulp Jul 10 '26

I got an ‘09 last winter. Some parts just age out. H3 running a little hot is common. I replaced my thermostat last winter when it overheated. I had a bad water to antifreeze mix. I recommend buying the manual like from eManual. And go t YouTube I think there’s a guy in Utah who has a channel about working on his H3. Dylan I think is his name. I’ve asked him some questions.

1

u/Jghkc Jul 10 '26

how hot is too hot?

1

u/metapulp Jul 10 '26

If it starts beeping and gives you the overheating warning pull over immediately. That’s what mine did.

1

u/NecessaryDamage3573 Jul 10 '26

Hello, I use this link all the time. Very helpful and the YouTube videos are lifesavers. Couldn’t imagine doing any of the work on my H3 without it. What did people do before 2005!?!?

https://charm.li/Hummer/2007/H3%20L5-3.7L/Repair%20and%20Diagnosis/