98 K1500 5.7 metal squealing

[Johnbirch]

Is there a fresh-air vent on the OTHER valve cover? What is it connected to?

The service manual will have a PCV system hose routing, and maybe there's an under-hood decal with that info too...but you shouldn't need it.

The passenger side valve cover has a connection to the air intake. It is in between the air filter and the throttle body.

 

[Schurkey]

Have you verified that there's mild vacuum at the air-intake side? In other words...that fresh-air inlet isn't plugged?

The PCV valve is in good condition?

 

[Johnbirch]

Have you verified that there's mild vacuum at the air-intake side? In other words...that fresh-air inlet isn't plugged?

The PCV valve is in good condition?

Yes, there is decent vacuum on the air intake side. I just replaced the PCV valve as well, with no difference.

 

[Schurkey]

If I pull the vacuum hose with the PCV off, the squealing goes away.

Engine whistles at idle when PCV valve is plugged-into the valve cover.

Removing the PCV valve from valve cover eliminates the whistle?

 

[Johnbirch]

Engine whistles at idle when PCV valve is plugged-into the valve cover.

Removing the PCV valve from valve cover eliminates the whistle?

Yes

 

[Schurkey]

Well, if the other valve cover is venting like you say...I'm out of ideas.

 

[Johnbirch]

So just an update. Out of desperation I changed the intake manifold gasket, and my noise went away.