I have a 2006 H3 with just over 100K miles. Several days ago it started to make a rattling noise that I can only describe as, "The sound a baseball card makes in a bike spoke, only mechanical and louder." It is not the tick of a valve or a knock, but a sound of its own I've never heard before in any car or truck.

The sound is strongest with the accelerator applied at low speeds (above 2500 RPM, under 40 MPH) The sound increases and decreases with engine RMP.

The rattling is totally absent in neutral and park. (This leads me to believe it's related to the drive-train in some way)

As a reference, the sound seems to come from somewhere underneath/behind the radio/gear selector area. Here's some info on the truck you may or may not need to know. Let me know if you guys have any questions.

-New Oil of correct weight
-Transmission has less than 40K Miles, fluid level good.
-There's is, and has been for a while, a lot of play/slack/slop in the drivetrain. (Jolts hard if you let off the accelerator at speed and then jump back on the accelerator) This problem has been slowly getting worse since I got the truck.
-Have had problems in the past with this truck getting stuck in 4WD, differential had been worked on about 20K ago to get "unstuck" from 4WD.


To make things more confusing the problem/rattle is intermittent, coming for several hours, then leaving for similar periods in time. Engine and ambient temperature does not seem to effect the rattle. I'm broke and I really need to figure this out before it gets worse, any help would be appreciated!

 

so you're driving 65 mph,you shift to neutral and its quiet,back to 4th and the racket is back huh?

oh,above 45 does the torq converter lock up?

and the tranny was changed huh

 

I'm not one to offer mechanical advice, but, I have a similiar vehicle with similiar mileage and I just took it in and they said it was the cv joint on the front driveshaft.

 

Well to start you probably need a new cross member bushing to fix the clunk your getting from letting off the gas and stepping on it again. It is a well documented problem.


As to the noise if it increases/decreases with rpm then you need to look thru the engine and drivetrain. Exhaust shields, Axle shafts, front driveshaft will all make a ticking noise when worn.

 

I had the same exact problem, Binding front driveshaft..( not serviceable) Driveshaft was replaced

 

I don't know exactly what you mean by rattling, but start with the easy stuff.

Loose heat shields cause crazy noises which seam to come and go under load. Get under there and see if the exhaust heat shield is touching anything. Have someone put it in gear with the brakes on and look/listen around under there. Cost = $0 if you use a long screw driver to bend it away from whatever it is contacting.

 

I just bought a 2007 h3 3.7, also had moderate rattling comming from the front. Took it to local GM service center/dealership, they said that both motor mounts were broken, and will be replaced under warranty. But they neglected to tell me that they were going to leave early on Saturday(today), and that the work will be done by Tuesday. I guess they want to get a holiday weekend's worth of storage fees from GM. Yet I'm out of a ride for New Years.

 

P.S. I took it in Yesterday at 8am.