bad blowby

[robz95xj]

my truck has a blowby issue, i put a 2 liter sprite bottle in the middle of the ccv line so shit wasnt goin everywhere and makin my air filter a mess, the truck has gotten a compression test and all cylinders were well in spec, theres just clear water and some foam in the sprite bottle, draining the oil it looks fine so wtf is it?

[01mmmz28]

Buy or make a catch can.

[robz95xj]

what do you think the sprite bottle is? any idea what could be causing it? could it be a head gasket?

[01mmmz28]

no, blow by is normally caused by the rings. Either having gapped over time or from being installed wrong. Does the vehicle in question have a PCV system? if so, just remove the PCV check valve and go to lowes and hit up the plumbing section and find the correct diameter double ended female union and hook up both ends of the tubing where the PCV valve used to be and clamp the ends after the install, that will help some, it did on mine. You should really get a real catch can or get the homemade version from home depot or lowes. It is a air compressor filter, made by husky, it has a "in" line and a return line...you need a catch can w/ both for it to be affective.

[joeo]

I would perform a leak down test. During the test listen to where the air is coming out. If bubbles are coming into the coolant, then it's likely that the head gasket is blown...if are is coming from the crankcase, then it's probably bad rings, or a broken ring land. If air is coming out the intake/exhaust then it's a stuck valve.
Leak down tests are much more telling than a compression test.

Leak Down Testing

-Joe
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