Thinking about buying H3
 

I am thinking about buying a Hummer H3 that's ten years old and has 120,000 miles. How frequently can I expect problems? What major and minor problems are H3s known for? Thank you!!

Read through this forum and you will find all your answers. Good Luck.

What year? It makes a difference. Hard to help without that.

10 years old could be an 2008?
So it also could be an Alpha (V8) or an I5?
More info is needed or maybe a link to the listing.

I'd say by this point Hummer H3's are a dieing breed. The last one came off the assembly line 7+ yrs. ago and at a rate of 12k annual miles that would be minimum 84k miles.
There are items with all makes and models that need maintenance and with mileage heading north of 100k-200k there will be an equally good chance that extra service will be needed.
I always try to recommend that a person either have deep pockets or be well versed in repairing vehicles if you by used with high mileage.

I'm not going to sugar coat anything. My lady has a 06 H3 with about 140k on the ticker and just tonight was commenting that she would be renting a car for her coming trip out west because she feels the H3 has gotten to old and questionable to take. That's of course silly to a guy like me (I do all the work on our vehicle's when I can) but not to a woman driving cross country.

My H3 has 77k miles and I would not hesitate to take it to Moab tommorow but lol again that's me.
My Jeep has 218k and I'd drive it to the city over and back but that's about it. Way to many miles to take to Colorado or Washington State.

Jmho

Compared to every other car I drove, my 06 H3 never left me stranded and I have 115K miles on it.
it is showing age, but im keeping it (or swapping it to an H3T if I find one)

2006 h3
 

My 06 H3 Adventure has 95K and so far the only real issue was a cracked radiator. She's never left me stranded but she's showing her age. I consider myself lucky because the 06 is the most unreliable year..

Same here - I have an 07 H3X (~84k miles) and the only "major" work that I've had done is replacing the radiator in 2014. I suspect that I may soon be replacing my thermostat as well. Other than that, I can't stress enough how important routine maintenance is for ALL vehicles.

Another thing to consider - how many owners has the vehicle had?

I have 2006 H3 and I am mechanically inclined to do a lot of work myself. Mine has 213K on it and I have changed radiator/thermostat which is common on these vehicles, water pump, battery, maintenance is key with fluids, done brakes front and rear twice, full tune up with new coil paks, just did the front diff mount bushing, replacing the Dampeners on front and rear now. The vehicle is pretty reliable in my experience, I use Amsoil products and it seems to help. Oh yeah I had to put bulbs in interior AC and heater lights. I think honestly the only one issue is the tire sensors that alwys come up on dash but Im not going to deal with it right now, SERV TPS light has come on and off for a while but it doesnt effect the vehicle. Other than that the plastic on the outside gets briddle and comes apart. I guess it all depends on what you are looking to do with the vehicle, overall I have had an awesome experience with the H3 and would buy another if I had the money they are little tanks but even tanks need maintenance.

My H3 has also been very reliable. One fairly expensive upgrade you may encounter at that high of mileage could be broken exhaust manifold bolts and a cracked exhaust manifold. Parts for an I5 are around 800-900 with core replacement through GM Parts, probably around 1,500 for a local shop and labor.