new bigport rebuild enginehas squeak once it develops vacuum, goes away when oil filler cap opened, I have significant vacuum through dipstick hole ann throughout crankcase, exhaust header EGR is capped once header installed, charcoal canist off and tube plugged, , is the engine suppsed to draw fresh air from aomewhere?

Do you have the line from the exhaust valve cover to the intake manifold? Some pics might help point stuff out

dont believe there ever was one on exhaust side, intake side has moroso oil/air seperator between intake plenum and valve cover as a PVC replacement, I'll get some pics up

That's what I meant, intake side.

what we did was move the vacuum line from the intake plenum to the intake in front of the throttle body (reducing the amount of vaccum) and it stopped squeaking