strange hard noise in my H3
 

Hey guys, first of all i'm new here and i'd like to present myself. My name is Daniel and i'm from Monterrey, México. I bought some time ago a 06' H3 Adventure for my weekend bike trips. I love this iconic SUV, I've wanted a Hummer so bad since I was like 13 years old. The H3 was the most suitable for my lifestyle. My daily drive is a Mercedes, but on the weekend if I go to the mountains I take my H3. It has 133,000 km, which is close to 85,000 mi.

The problem is:
there's a strange sound coming from beneath, I think may be the transfer or the tranny. If i'm driving at 7-25 mph without touching the gas, then press it theres a hard sound and you can feel it, like two metals bumping into each other. I know how a car works but i'm not so much into it. The truck is mint, I love it, but this issue is driving me crazy.

I tested another 06' H3 with 60k miles and did the same sound, but it was less frequent

has someone had this same issue? how can I fix it and what are the costs?

also, when you're on the gas and then let it go at low speeds I feel the engine revs down like if it was going to go off, and then it recovers to idle, i've seen lots of Hummer do this, how can I fix this?

Greetings from México... ¡Saludos!

Your strange sound issue is GM 4WD or AWD driveline slop, normal. There is a lag in the driveline that you notice at low speed when not under load and then apply throttle. The engine begins to apply torque to the crank shaft, then to the T Case, then to the front and rear drive shafts, then to the diffs and out to the axles, when the torque is fully loaded you may hear or feel a clunk as that lag is taken up. Every GM 4wd truck I have had does this under some certain circumstances.

#2 is false stall, cause by a dirty Throttle Body. Look up how to clean it using ONLY Throttle Body cleaner. One of the most common missed simple maintenance items for fuel injected vehicles.

Welcome to HF!

Well now I'm curious Doc, is there any way to fix this?

the only time i feel, a soft thump, is if i shift to neutral at a long light,then pull back to drive and even gently touch the gas.
if i keep it in gear while sitting i never feel any play,and never while moving slow/fast on and off gas.
im at 60000 miles of decent polite driving,no rough stuff,just fun driving!
the h3 is my all time daily drive, nothing else on the road.

Thank you very much for your reply!

I will clean the throttle body asap.

¡Saludos!

Just to be safe check ALL of your U joints for slop.

Fix what? Most every brand vehicle with a Trans, T Case, 2 drive shafts, and 2 diffs is going to do the same thing to varying degrees, less when brand new, more when components and U Joints are worn.

People who have never driven a 4X4 truck before get all excited when they first experience it, ain't no big deal.

I believe your clunk may be the same as mine which I still have not been able to get fixed yet because shop wants like 1k to fix. Front Cross member bushings I think what it was called. If you put it on a lift and hold the brake and shift from park to drive and back again you can see the front diff move up and down because the cross member bushing wear out. I believe there are other posts here on this so do a search. I also think unless you do some home remedy you have to get the whole cross member part that has the bushing installed already. It's also a pain to do. When I got tires last year they put it on the lift and showed me the movement. They quoted me a little over 1k to fix but since I was already spending 1k on tires I could not have them do it. If your easy on the stops and accelerating then you won't notice it too much but if you hard brake and stomp on it you'll hear the big clunk. I'm kind of miffed at GM/hummer for making this bushing a not so easy to replace part as that is the one and only complaint I have on my 06 hummer with going on I think 72k miles now. Good luck!

Hola Gomer, thanks for your help

I did what you told me and fortunately the diff is still and steady. Later on i'll check the joints.

There's also some squeaking on the suspension, can I fix this by giving it an underbody oil bath or is it something on the suspension?

¡Saludos!