Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - possible blowby?
View Single Post
  #2 (permalink)  
Old 01-08-2013, 09:03 AM
cobalt327's Avatar
cobalt327 cobalt327 is offline
WFO
 
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Location: Atlanta
Age: 60
Posts: 5,037
Wiki Edits: 1616

Thanks: 128
Thanked 598 Times in 547 Posts
Quote:
Originally Posted by CapriceLTZ View Post
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.

Reply With Quote