Originally Posted by CapriceLTZ
I have a 91' caprice ltz with 183,000 miles on it. why is the oil coming up thru diptube? i replaced the pcv valve and there is suction when tested.
Suction at the PCV valve or at the dipstick tube?
Blowby would cause there to be pressure
at the dipstick tube and breather. The PCV system will negate some of this, but if the blowby is too bad, it'll overwhelm the PCV system.
One reason for oil to be coming out of the tube is too high of an oil level. Another is if the bottom tube inside the crankcase was missing/broken off. But if you have a bad ring or piston, you may see a puffing of blowby from the open breather at idle (see video below).
It's time you did a few tests. A leakdown test would be preferred over a compression test, but either will show you if you have leakage past the rings. A vacuum gauge
can tell you quite a bit if you interpret the readings correctly.