Rattle rattle rattle

[marc.l]

Got a strange rattle on m113k , I thought I would find it when I did my service , cam cover gaskets , new spark plugs and oil change .
The noise, only at part throttle , on power and over run , some times dose it other times not . Sounds like a lose plate vibrating at a certain frequency from the middle of the engine .
No problems found under the cam covers , exhausts not rattling , removed belts and still dose it . It's not a rocker arm , it's not any thing lose around the engine , not a heat shield ( but that's the sort of noise ) sound like from under the super charger .
Any body got any idea ?

Marc

 

[Alps]

supercharger bearing?

or bearing on another pulley?

 

[marc.l]

supercharger bearing?

or bearing on another pulley?

No mate , removed all the belts and spinning the charger by hand no noise or rough spots . Can't find any thing lose
Marc

 

[SavMan]

Its the TB or bypass valve butterfly, does it happen more after a short sharp blip on the throttle?

 

[marc.l]

Its the TB or bypass valve butterfly, does it happen more after a short sharp blip on the throttle?

Hi Paul
Yep , if I blip the throtle dose it on over run , under load it dose it only briefly . Is it a problem other than the noise ? A bypass valve on the way out ?
Thanks
Marc