H3 makes rattling/clanking sound behind glove box starting between 1,000 and 2,000 RPM and at about 20-30 mph. Noise sounds like air passing over paper or thin metal with an intermittent clanking sound. I noticed the sound shortly after I picked up the H3, brand new, on Aug. 27, 2009 and it appears to be getting noisier as time goes on. The sound is most apparent after the H3 is used for 20 to 30 mins., turned off, and then restarted and driven. H3 does not make noise when revving engine in stationary position.

Any useful comments or suggestions would be much appreciated, thanks!

 

same issue, picked up my 2009 H3 yesterday from the dealer. I was driving a "loaner" h3T and didn't notice this noise. The loaner was a automatic, mine is a manual shift. Its not very load, but noticeable. You hit it on the head, "wind passing over paper"

 

My 2009 H3 developed a very slight rattle that got worse and it turned out it was the bracket between the engine and the exhaust pipe at the bolted joint after the exhaust manifold. I tightened it up and it went away. I don't know if this will help but it's worth checking to see if it's tight.

 

Thanks for replying jasonmb and oruna1...I am bringing the car into a Hummer dealer on Wed., 9/30 and will let you guys know what happens.

 

The Hummer tech drove my H3 and, thankfully, heard the noise. He said it sounded like a detonation problem (a.k.a. engine pinging or knocking) so he tested the gas and said the oxygen content was too high which lead to detonation problems which causes the rattling I was hearing. This makes sense, since the noise got worse after the car was driven for awhile (which I mentioned before) and I subsequently noticed the sound was most frequent after driving up a big hill after the car was running for a period of time.

In conclusion, I was instructed not to go to the gas station I was consistently using and they also suggested I try a higher octane as well to resolve the noise.

After my current tank is almost empty, and I fill up with gas from a different station, I will post again here to let forum members know if the problem has been completely resolved.

PS

Check out http://www.youtube.com/watch?v=ilXlj0wYZZ4 to listen to Engine knock and pinging on 3.7L Inline 5 - Hummer H3.

 

Hey how ya doing. Thats actually my video and Im having a major problem with knocking on my 08 h3 with 21k miles. It knocks with 87 and 89 octane, I still havent tried 91 octane. I think its BS to have them tell us to run a higher octane when the i-5 was made for 87. After two visits to the dealer they still cant figure it out and tomorow Im dropping it off at another dealer. If they cant fix it Im going to have to take it to court.

 

Thanks for your reply; much appreciated. The same thought crossed my mind about the engine being designed for 87 octane as well. My engine does not making a knocking sound per se. The only symptom is a vibrating metallic sound, which I can hear your video. Does your engine have other symptoms as well?

I also was wondering, since H3s have a Chevy Colorado engine, if these owners have similar problems. As soon as my car is on empty, I will be filling up with a higher octane from a different gas station and will post back here.

PS

Whatever state you live in, you should look into their car Lemon laws if you have not already.

 

Its more like a pinging/popping sound, or even paper in the wind. It only occurs after the h3 is nice and warmed up. Its a lot more obvious going uphill with the A/C on low or towing a trailer. It seems that once it starts, it keeps pinging. When it starts to ping uphill, I can feel the h3 losing power, almost feels erratic the way the rpms climb. Its probably due to the pcm pulling timing due to the pinging. Once the pcm pulls timing due to the signals from the knock sensor, the pinging is supposed to stop but for me the pinging just continues.

 

It's 10/06/2009 and I just put gas from a different gasoline station in my H3 this morning. The H3 needle was on empty and I ended up putting in 20.254 gallons of 93 octane gas. (I wanted to put in 91, but they only had 93.) For the first 6 miles or so I still heard the vibrating metallic sound and then it started to wane. (This sound could have been accounted for by the previous 87 octane gas still in the gas line.) Later, at about 18 miles, it appears to be completely gone. I hear a single ping here and there, but no vibration, but that can be a stone hitting one of the 4 shields underneath the H3 or some other sound. I must admit, that after listening to the sound for about 1530 miles, one becomes sensitive to any sound the H3 makes and as we all know, it's not the quietest engine (the H3 currently has 1550 total miles on it). The H3 also appears to run much smoother now and accelerates easier. Tomorrow (Thurs.) I am taking the H3 for a much longer drive and will be doing some serious hills (where the rattling was at it's loudest). I will post here again after that trip.

I'll be pissed if I end up having to put higher octane gas in the H3 for the rest of it's life since the engine is designed for 87 octane. I read a long *.pdf from GM about the engine http://media.gm.com/us/powertrain/en...6/09_LLR_n.doc


Interestingly, it states:

The inline engines have a high compression ratio but still use regular-grade gasoline, due to optimized calibrations and combustion. Typically, high compression engines require high-octane gas to produce maximum power, or to avoid the potentially damaging effects of spark knock or “detonation.” The Vortec 3.7L’s 10:1 compression ratio delivers the horsepower and combustion efficiency advantages of higher compression, yet allows this inline five-cylinder to operate at peak output on regular gas. These seemingly incompatible objectives were achieved by optimizing combustion chamber design and airflow to the engine and by applying advanced engine management technologies.




Maybe, at least in my case, the regular gas stuff is not accurate...we'll see....

 

in the car's booklet i saw it suggests 91 octane, that made my day lol. 91 is the lowest they sell here so its all good. i put in 95 once, no difference