Strange engine sound

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..

quote:

ORIGINAL: Dennis

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.

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.

quote:

ORIGINAL: inked

quote:

ORIGINAL: Dennis

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

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

quote:

ORIGINAL: Dennis

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..

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.

quote:

ORIGINAL: Dennis

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

If this noise is ping, spark knock, etc., I wonder if the ethanol in the fuel has something to do with it. I usually get gas (87) at Shell, which in my area is 10% ethanol.

I had the noise also but thought it was normal, but now that you guys are all talking about it, i know what you mean. Mine though is very very faint, to the point that you can't hear it unless the radio is off and the windows are closed. I hear it through the firewall. The noise actually was louder for me with higher octane. Once I disconnected the battery overnight and ran the tank dry and refilled it with only 87 octane, i never heard it again, which is strange because according to everybody here the ECU/PCM should not have remembered or had anything erased. I don't know what happened but it dissappeared after that. It may have something to do also with the colder weather. The gas companies change mixtures from summer to winter seasons. That affects your engine to some degree. It may be that you need to switch to a different brand, but trying to figure out who has what mixture in place is impossible.

quote:

ORIGINAL: RobD

If this noise is ping, spark knock, etc., I wonder if the ethanol in the fuel has something to do with it. I usually get gas (87) at Shell, which in my area is 10% ethanol.

That may be it..try non ethanol and higher octane..

quote:

ORIGINAL: Dennis

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ORIGINAL: RobD

If this noise is ping, spark knock, etc., I wonder if the ethanol in the fuel has something to do with it. I usually get gas (87) at Shell, which in my area is 10% ethanol.

That may be it..try non ethanol and higher octane..

In my area, I think they all have some percentage of ethanol, unfortunately. Thanks Dennis.


HummerGuy, thanks, maybe I'll try that. The volume of my noise is similar... with the windows down and/or the radio on, you'd really have to listen for it.

Dennis: I was told and have seen on the news that it was a law or federal regulation to have 10% ethenol on all gasoline. Maybe that's just around here. You can't buy it in Chicago without it. All the pumps say By law, 10% ethenol is added to all fuels, or something to that effect. Perhaps it's just an Illinois law.

Hmmmm...Out here in the SW, it has to say it on the pump somewhere if it has 10% or more ethanol in the blend...But We have non-ethanol everywhere out here and I rarely see any of the 10% ethanol stations, if any.

But 10% ethanol will certainly cause predetonation..Perhaps when you powered down your PCM it relearned the fuel you are burning with ethanol in it...So then after thinking about this now for a minute, you maybe right on the mark for a fix for Rob then..Hmmm..very interesting indeed!

This may answer both of our questions. It is a rule in the Chicago/metropolitan area:

http://www.illinois.gov/PressReleases/ShowPressRelease.cfm?SubjectID=3&RecNum=1165

And here is the new Illinois law going into effect in Jan. '07 for the entire state.

http://www.ilga.gov/legislation/BillStatus.asp?DocTypeID=HB&DocNum=5532&GAID=8&SessionID=50&LegID=24815

It looks like it's local to our state. I guess this answers the question, but with my mom's boyfriend being a retired auto teacher, he warned me about this years ago, because he was mad about it, that putting ethanol in an engine that is designed specifically for gasoline causes the engine to break down quicker, as in wearing out, and puts some kind of stress on certain engine parts. There are all kinds of things like this out on the web. It's one of the drawbacks of living near a big city. Now that I'm moving out 45 miles away from the city, they are going to institute it statewide. If you do research on the negative affects of ethanol, it's very interesting what you find. Just some heads-up

Since I deliver gas for a living, fuel is a subject near and dear to me. Almost all of the major metropolitan areas require ethanol because it reduces NOx. It also raises the octane slightly as well. Some places, like the state of California, and other high congestion areas require reformulated gasoline. I don't know what they do to it to make it reformulated becasue we don't have it here. What ever your local laws are reguarding the minimal ethanol content and other additives will be consistant through out all of the gas stations in that area. There are some exceptions, Arco/BP runs 10% ethanol all year while everyone else only runs it when required by law. In my area of Washington, there is no requirement for it ever, but Arco still uses it. It is required by law to inform you if the fuel contains ethanol, and during what times of the year if it is seasonal.
From the refinery, gas is gas. It all must meet minimum federal standards and industry standards before being sent into the pipeline. Reformulated gas must meet the minimum federal standards to be considered reformulated before it goes into the pipeline, and then it can only go to reformulated areas. Since I don't know much about that, I won't say anything more about reformulated gas. All of the refineries dump bulk fuel into the pipelines and then take out the same number of barrels at their storage facilities that were put in at the refineries. This is why gas is gas reguardless who refined it. Once the gas gets to the storage facility the company additives are put in, such as V Power for Shell, and Tecron for Chevron/Texaco. These addititves are all that makes on brand better, or different, than another. These additives are injected into the fuel as it is being loaded onto the truck that takes it to your local filling station. Local chain gas stations and "Mom and Pop" service stations who don't own thier own refinery buy the generic gas from the larger companies and they get a generic additive package. This package is the minimum of all the stuff required by law in the area the fuel will be sold in. That is why there can be a noticeable difference in performance between Little Guy gas and Big Oil gas.
For the best, most consistant performance, buy gas from national brands becasue the only difference in thier gas will be the local requirement changes from one area to another. Generic gas stations can buy thier gas from who ever they want and you have no idea where it came from or what was in the additave package.
Keep in mind, however, that the boundaries for who gets what as far as additives are strange. In one metropolitan area you could have loose federal standards in some places all the way to tight city requirements in others such as an ethanol requirement in some parts of town, none in others, high RVP in some places and low RVP in others. I know this sounds contradictory to what I said above, but within a regulated area evrything will be consistant and there can be several regulated areas in one metropolitain area. I buy gas at one station, and try to be consistant with buying gas there. When I have to buy gas somewhere else, I try to stick with the same brand.

That's great to know. You kinda took all the questions and mystery out of who gets what gas.

Yes Linus is full of gas..if you know what I mean J/K

Seriously, he's always been very helpful for me.