Grumble...Rattle.. Idle..??

[Spiggie]

When I am in idle at like a stop light or stopped on a driveway picking someone up if you listen there is a noise comming from the engine/under it? I have no idea what it is and honestly dont think it is any harm.. but just wondering if anyone knows what this is? It goes like ratttttlllleee....pause....rattttttllleeee...pause....and repeat until i let off the brake and accelerate. i dont think its a rattle..more of a ...gerrummbtle :nerd:

 

[DC runner]

Then it is a rattle. What kind of engine do you have? Both the V6 and V8 produce vibrations, vibrations the engine mounts attempt to control. It is perfectly possible some wire or metal or plastic flap happens to resonate on just the same frequency your engine vibration is causing.

When your engine is in drive, straining to move, and you have the brake on.... the kinetic energy may not quite be kept in check by your Auto Transmission and as a result you get a slight vibration.

 

[ARunner]

Resurrection here. I have a V8 and also have this annoying resonance. It doesn't sound to serious, but is very annoying. Putting the truck in neutral or even idling up the engine with the brake still down just 100 rpm makes it go away. Wondering if anyone has found a fix for this.

 

[CXS]

It's probably a heat shield, check to see if yours is loose/bent.

 

[ARunner]

Thanks. I assume we are talking catalytic converter heat shield? Are you giving me what you believe to be the most logical culprit or what youve experienced first hand? I only ask for context. I also would first suspect heat shield on the catalytic converter or elsewhere, but since it seems this is fairly common, wanted to find out from others if there was a verified cause and fix. Im lazy.

 

[CXS]

Yes, the cat heat shield based on my experience. All I had to do was bend mine a bit, specifically the drivers side on the V8.

 

[ARunner]

Awesome! Thank you. Sounds more like driver side to me, but then again, thats usually where I sit while driving...