TRUCK IDELS UP AND DOWN IN PARK OR DRIVE. ACCERLERATES UP ON ITS OWN EVEN WHEN WARM.MAKES A LOUD WINEING NOISE LIKE TWO MALE CATS FIGHTING.REMOVED BELTS FROM TRUCK STILL MAKES THE NOISE.IT SOUNDS LIKE THE NOISE IS COMING FROM THE UPPER MANIFOLD NEAR THE LOCATION OF DISTRIBUTER. COULD THIS NOISE BE PART OF THE FUEL INJECTION SYSTEM? OR IS THERE A VACUM PROBLEM UNDER THE UPPER MANIFOLD?
WHATS IS CAUSING THIS LOUD VACUM LIKE NOISE? on 1996 Chevrolet Suburban 2500
by REAR1STADMIRAL in El Mirage, AZ on February 13, 2011
ANSWER by ZeeTech on February 13, 2011
It's probably a vacuum leak. It can be traced down with a smoke pump. It will inject a thick smoke into the intake and makes leaks visible. Zee
ANSWER by techlund1 on February 15, 2011
Sounds like a vacuum leak a smoke test would find this