Well I thought my 2007 H3 had a cracked exhaust manifold after I started hearing a ping, knock. I bought it used with 75000 miles a couple months ago. Just last week I started noticing the ping, happened during sub zero temps. So...I pulled the heat shield to look for crack. No crack but the manifold has 3 broken flanged head bolts with about a good 1/4 inch still showing. The worst part is there is a stud in the slotted hole nearest firewall that was obviously replaced by previous owner and it was wallowed out oval. I will be taking it to an real good exhaust guy in town. I don't anticipate the broken bolts to be too much of a problem for him, Just wondering if the "wallowed out" bolt hole can be fixed??? Any thoughts or ideas? Oh yeah and I think I'm starting to get shift fork symptoms now, starting to bind sometimes in tight turns in and out of parking spaces. Damn, I loved this H3 for the first few months and now I'm starting to hate this damn thing....

 

if it actually is and you actually drive it that way without a fix you will wreck other stuff.
it stresses the drive train complete, all of it.

matter of time.

 

Yeah, have to drive it to exhaust shop to get manifold bolts fixed, otherwise it is parked. Not driving much and avoiding binding when I do. Next stop is getting transfer case looked at. I've never had good luck with GM vehicles in the past, sorry I tried again. I think GM owners love their vehicles so much because they are always working on them LOL!

 

Your real good exhaust guy will be very lucky if he does not break off 1 or more of the bolts trying to remove them. There have been times when every bolt breaks off flush with the head because of the galvanic like reaction of corroded steel bolts in aluminum.

Fingers crossed, best of luck.

 

Thanks Doc, I already pulled all the other bolts myself and replaced with new, one at a time, until I get gaskets and o2 sensors in and get the vehicle to him. And instead of locktite I used some old Marvel Mystery oil on them before replacing so he could remove them with ease. I am really concerned with the bolt hole at Firewall that is wallowed out oval. Someone had put a larger different sized stud in that spot instead of M8 1.25 30MM flanged bolts that are in the other spots. I am hoping he can drill and Heli-coil. The bolt hole on Maifold at that spot is slotted. I am sure it was a vibration issue. Aluminum kinda sucks sometimes. I don't know what else to do short of replacing head. It's parked and not moving until Monday. Wish I new exactly what type of bolt came in it from factory??? stud or the flanged bolt???

 

I have a rattle at 1900 to 2000 rpms.. My H3 has 71000 on it sounds metalic... Not a heat shield.... All very tight.. Could it be a bad cat.. Noise sounds likenits coming from behind the passenger glove box.. Help

Scott

 

Thats how mine started, check manifold for cracks and manifold bolts are tight.

 

Update on broken manifold bolts. I ordered flanged manifold bolts and firewall side stud, Gasket, Both new o2 sensors, and New heat shield @ $153. Local shop dug out the broken bolts and used a thread repair kit on the firewall stud hole, plus they installed everything else for $180...nice! Need advice on the shuddering turns, binding wheels, shift mode fork issue. I brought in the technical Service Bulletin 08-04-21-005A to local dealer to find out what it would cost too do the work for this issue. One was $480 and another was $300 but that is without any diagnosis. Should I just pay to have mode fork replaced or pay to have them diagnose and change the mode fork? Not sure what they will charge me for diagnosis...

 

After all of the reading I've done on here I thought for sure I had the dreaded shift fork issue. After calling the dealership and talking with service manager and a tech, both assured me that they have only seen a couple of the bad shift forks since they started selling and servicing Hummer H3's. I made an appointment to have it diagnosed. In the meantime I thought I would change out the initial suspect ujoints before hand. Didn't look bad at all but after jacking up I noticed rear Ujoint was shot. Funny because I dind't have the typical vibration under the seat like other vehicles with the bad Ujoints usually do. Just the binding in turns, crowhop and shuddering. $120 in parts and the problem is cured. Runs like a champ! Guess I just spent too much time reading the forum and talked myself into the worst case scenario.....

 

My 07 has the plastic T Case shift fork, never a problem so far. My Grandad used to say: "If it ain't broke, don't fix it." I am still listening to those words from a very capable self taught mechanic.

If you have to go into the T Case for something else that needs fixin, then swap to the metal shift fork, otherwise just keep truckin.