I am looking at getting a silverado SS with a magna charger and longtube headers.

The truck has 70,000 somehting miles on it and the charge has been on it for about 30,000 miles.

At idle the truck has a slight knock to it...not extremely loud but you can hear it.

I keep reading and researching that it could be the charger causing low boost and causing the knock...or it could be piston slap.

Now it's moderatly loud..you dont have to listen close to hear it...drove the truck around for about 30 and still didnt go away after the truck warmed up.

Only does it at idle..as soon as throttle is applied it goes away.

Could the charger or something else be causing this.

 

Could be tappets clicking. Is it low on oil? If it is boosting at idle it's a simple fix to replace the boost check valve that's on the side of the blower.

 

Have you checked your idler pulleys or the tensioner?

 

Does the truck have an aftermarket Camshaft? Have you checked Vac at idle? The blower will knock if there is low vac at idle from a "lumpy" camshaft. Take the truck to a mechanic and have it checked over, normally the blower will not make any noise at idle.


Spoolin, that is a vacuum referenced bypass actuator....not a check valve.

 

Not low on oil, not building boost at idle, stock cam.

from i seen it looks like the idler tensioner was loose and even sounded weak.

It sounded like it was coming form the bottom back but couldnt tell for sure.

 

Very well BlownChevy! Thank you for the correction Sir!

 

Just bustin your web *****

 

I stopped loving you the day I got back from sea!

 

maybe check for play in the snout of the charger?