Symptoms
A coolant puddle at the front, a crack in a plastic tank, rising temperatures when towing.
The fix, step by step
- Drain the coolant, then disconnect the hoses and the transmission cooler lines.
- Their retention clips are the worst part of the job, and one owner drove for a month with a clip not fully seated.
- Lift the radiator out without bending the fins; the front-hinged hood makes this awkward alone.
- Replace the lower hose while you're there, then refill with DEX-COOL and bleed the system.
Tools & part numbers
- Drain pan
- trans-line clip tool
- something solid to stand on in the engine bay.
Where to buy the parts
Radiator (catalog, 2005 H2)RockAuto ↗
Radiator hoses (catalog, 2005 H2)RockAuto ↗
Coolant (catalog, 2005 H2)RockAuto ↗
Hunting a used or discontinued part? Search eBay Motors for AM General Hummer H2 parts →
Rated for a competent home mechanic with a decent tool kit. Confirm torque figures, fluids and procedures against the factory service manual for your VIN, support the truck on stands rather than a jack, and work at your own risk (disclaimer). Some parts links are affiliate links, which pay us a small commission at no cost to you.