Rattling noise at low RPMS 2006 1500

[R6Ivy]

Hi, I'm pretty new to this website. Came across it when I was looking for an answer to my problem . . . I don't know too much about trucks.. cars....4 wheel vehicles. I just bought this 06 crew cab 1500 silverado 4.3L had about 80k miles on it. I actually noticed the sound when I was test driving it from the dealer. Now it has about 101k miles and noise is still the same. it makes a rattling noise, almost like a metal noise at LOW rpms only. Doesn't matter if its 35 or 75mph. Have to be cruising like slight amount of acceleration. Sounds like its coming from the engine.. I checked a bunch of forums all saying different things. my truck is stock, as far as i know.. one of the forums mentioned it could bea bad alternator, but I have no clue. any help? Sorry I'm a complete noob.

Ivy

[brucelimerick]

Probably knocking. Pre-ignition. The cylinder is firing a little too early and the knock is caused by the explosion hitting piston before it gets to the top. My 01 will do it sometimes at low speed and low RPM's when it is cold. Unfortunately this stuff is all sensors and computer controlled now. Low octane fuel can cause it too. One way to check this is run your gas tank down near empty and put a part tank of hi-test in, 93 octane. I believe there are sensors on the engine that are supposed to sense knock and tell the computer to adjust the timing a little to get rid of it. The higher octane fuel should make it better. I haven't had this problem so I haven't done much research on it but I'm sure there will be at least a few on this forum who have.

Vehicles are very complicated now a days. Some things even get expert mechanics scratching their heads. You are smart enough to have asked the question. I hope you know a good trustworthy mechanic.

[LowandUseless]

I had the exact same problem on my truck(1999 1500 4.3) when I first got it. My problem was a few loose bolts and a some random wiring vibrating. Idk check that out first before jumping to thinking the engine is knocking.

[Wolfmanjohn]

"Low RPM rattling" brings to mind all sorts of possibilities...including a loose heat shield on a catalytic converter (spot weld broken). My son had that on his '99 'Hoe. A hose clamp was his friend.

[govener71]

My low rpm rattle came from where the y pipe meets the rest of the exhaust under the passenger side. There are two bolts holding the flange together and mine was loose. To check just tap on the exhaust around it and see if it rattles.

[CapitalTruck]

I was thinking a heat shield myself.

[R6Ivy]

Im prettysure its not pre-ignition knocking. Plus ive ran 93 since day one. But thank you

Probably knocking. Pre-ignition. The cylinder is firing a little too early and the knock is caused by the explosion hitting piston before it gets to the top. My 01 will do it sometimes at low speed and low RPM's when it is cold. Unfortunately this stuff is all sensors and computer controlled now. Low octane fuel can cause it too. One way to check this is run your gas tank down near empty and put a part tank of hi-test in, 93 octane. I believe there are sensors on the engine that are supposed to sense knock and tell the computer to adjust the timing a little to get rid of it. The higher octane fuel should make it better. I haven't had this problem so I haven't done much research on it but I'm sure there will be at least a few on this forum who have.

Vehicles are very complicated now a days. Some things even get expert mechanics scratching their heads. You are smart enough to have asked the question. I hope you know a good trustworthy mechanic.

 

I will have to check this thank you very much.

My low rpm rattle came from where the y pipe meets the rest of the exhaust under the passenger side. There are two bolts holding the flange together and mine was loose. To check just tap on the exhaust around it and see if it rattles.

[brucelimerick]

All this makes sense too, loose parts. All good hints. Also a cheap fix if you find something loose. A mechanic seems to always head for the most expensive fix first. Knock is a distinctive sound as are rattles. Without hearing your problem everything is a guess. A bad oxygen sensor can also cause knock as well. Not trying to beat a dead horse, just a hint if the other stuff doesn't work out. Everything seems to come down to economic interest and yours is not the same as the dealers.

[Christopher Bryant]

On 3/29/2014 at 8:14 PM, brucelimerick said:

Probably knocking. Pre-ignition. The cylinder is firing a little too early and the knock is caused by the explosion hitting piston before it gets to the top. My 01 will do it sometimes at low speed and low RPM's when it is cold. Unfortunately this stuff is all sensors and computer controlled now. Low octane fuel can cause it too. One way to check this is run your gas tank down near empty and put a part tank of hi-test in, 93 octane. I believe there are sensors on the engine that are supposed to sense knock and tell the computer to adjust the timing a little to get rid of it. The higher octane fuel should make it better. I haven't had this problem so I haven't done much research on it but I'm sure there will be at least a few on this forum who have.

Vehicles are very complicated now a days. Some things even get expert mechanics scratching their heads. You are smart enough to have asked the question. I hope you know a good trustworthy mechanic.

Catalytic converter or resonator