Hi fellas, I've got a quick question. When accelerating my '07 H3 under moderate throttle, say around half, the engine makes a kind of rattle type sound. It is moderately loud. It doesn't make the sound under light or full throttle, though. It also does not do it when reving the motor in neutral. I don't really remember this sound when the H3 was brand new. It's got about 1800 miles on it now. I did a quick search and found something about a balance shaft issue that makes a clattering sound at about 2300 - 2500 rpm, but does not affect reliability. Supposedly this issue was fixed during early 2006 production. I assume that's still within 2006 H3 production. My '07 H3 was built in June '06.

Basically my question is, what is it and is it just an idiosyncrasy of the H3 drivetrain? TIA

 

Rob, try this before you try anything else..

Run the tank to almost empty with the fuel left in (I assume 87 octane), then refill with 91+ octane..If it stops rattling on acceleration from a standing stop with full throttle (which could also be predetonation knock), take it in, as it sounds to me something off on the timing or PCM programming...Because it should not take that higher octane to stop the knocking, it should run perfect on 87 octane..

 

Damn Dennis - you're like an encyclopedia when it comes to Hummers - amazing!
This forum is pretty lucky to have you, lucky bastards - kidding

 

I don't know if this is the same noise, but sometimes I hear a sound that sounds like something light touching a spinning fan blade. It's more of a metallic whirrr...

Theres nothing better than trying to describe engine sounds. Makes me feel like a special person..very special.[sm=grin.gif]

 

At times I have a similar noise on acceleration that I thought might be valves or detonation but then realized it doesn't speed up or slow down with the rpms. Only happens occasionally and usually after driving for a while. I still haven't figured it out but have come to the conclusion that it's not combustion related. [sm=smiley25.gif]

 

Shucks!...Thanks man..But my knowledge is limited and humble..But I did stay at a Holiday Inn Express last week.

 

Dennis, I don't think it's detonating. It does not make the sound under full throttle or at high rpm. Plus, it really doesn't sound like a ping. For example, if I'm cruising at a steady and quiet 30mph, then give it like half throttle, it clatters/rattles. The more throttle I give it, the lesser the noise. Could it be piston slap or that balance shaft issue? It doesen't sound like it going to self destruct or anything, but it is a little crude sounding. Thanks.

 

The sound I'm thinking of, sort of sounds like diesel ping, Like a diesel engine sounds...But personally, try my idea at least, can't hurt.

 

I'll try it, thanks.

 

I got the ratteling noise also 24000kms .I think its a spark knock when using reg gas. I had the same noise in my 04 rubicon dealer changed the head and it solved the problem