95 bonneville oil cap vacuum

[SSlethal]

have a problem with a 95 bonneville , when i take the oil cap off the engine almost dies and there is a suction at the cap and also at the dipstick. like if i put a hose on the dipstick it sucks better then a hoover lol. is this normal

[LMP]

When the oil cap is on, it prevents the intake manifold from taking a large intake bypass through the positive crankcase ventilation (PCV) valve but when you remove the oil cap, the engine takes a large amount of intake air through PCV valve and that bypasses the normal air and fuel mixture feed. I'm not sure if that is 100% normal..I would suspect your PCV valve is stuck opened.

[Flatrater]

The PCV is located inside the upper plenum. Sometimes when the PCV is replaced a small black o ring that goes around the PCV is not replaced onto the new PCV which would cause your problem.

I would remove the PCV and check to see if you have this o ring on the PCV.

[SSlethal]

there is a cap on the front of the engine on the plenum that says pcv. it just twists off, but when i open it there is nothing there that looks like a pcv valve normally would.there is a o-ring on the cap and it is in place.but like i said the hole is empty.and i forgot to add that it is the 3.8 incase that matters.