Heat shield vibration noise around 1250rpm need help

[dryrunner]

I have a noise that sounds like a heat shield vibrating against the muffler. I can hear it when starting out around 1000 rpm up to 1500. Then when coasting back down it hits around 1250 rpm and stops around 800 or so. Sounds like the rear of the truck. Makes the noise in drive or neutral. I have had all tires off, been under checking every heat shield, tubing, etc. All zircs greased and all gear oil levels checked. Is it possible that a baffle in the muffler broke? It is driving me crazy.

 

[doru]

Does it do it when lifted on jack stands?
If yes, then get a helper to depress the gas pedal and you go and listen/look around the truck. Not recommended you get under though.

 

[NYC570]

Did you throughly check the muffler heat shield? I had to install big washers on the heat shield nuts because they "corroded" thru.

 

[dryrunner]

I will try on the jack stands. I have the 22 ton type.
I did check the muffler heat sheild by tugging on it. But worth another look. Thanks
The noise starts right off, cold operation.

 

[empty80]

Do you have an LRA tank?

 

[AZLX570]

I'd enlist the help of a friend or significant other to be on the gas while you're underneath to diagnose.

 

[Karbon]

It is likely either a catalytic converter shield (hose clamp to fix), or one of the aluminum heat shields that has corroded around the washers (add larger washers as a temporary fix). I really wish they used aluminum washers on those heat shields.

 

[dryrunner]

I placed the truck on 4 jack stands and ran up to 3k rpm. No vibration noise. Stopped at a light, in neutral, rev to 3k rpm, no noise. Start moving up to 1800 rpm vibration type noise, same on the way down from 1800 to idle. Been almost a year, maybe has gotten a little worse. I haven't seen any threads with a similar issue. Weird

 

[pvchaitanya]

there are multiple heat shields, some on the side of engine you can see through wheel wells, check if those are vibrating.

 

[AnyMal]

I placed the truck on 4 jack stands and ran up to 3k rpm. No vibration noise. Stopped at a light, in neutral, rev to 3k rpm, no noise. Start moving up to 1800 rpm vibration type noise, same on the way down from 1800 to idle. Been almost a year, maybe has gotten a little worse. I haven't seen any threads with a similar issue. Weird

Persists on throttle lift off at 1800?