Yep. Once you play with it, chances are, it will always give you issues. I am of that category. Replaced mine after my S/C install years ago, and now I encounter random issues with it. Imagine that....
Gary Noonan
'01 S/C VX / '18 Forester XT
In my opinion, the best thing a person can do to possibly alleviate excess oil usage in a VX is replace the PCV valve with a simple breather filter.
so by eliminating the pcv you keep the oil vapor inside the crankcase instead of venting it into the intake manifold - which should lead to less oil burn but more sludge in the engine since that's the entire purpose of the system is to prevent oil contamination and sludge formation...but is the vapor able to actually vent through the filter? if it is venting properly and not allowing it to build up inside you would think the filter would need to be changed often because of all the oil vapor coming through it - it does makes sense that it would burn less but are you sure that is what is best for the engine? i guess it could be kind of a wash - on one hand you would burn less oil but need to change it more often because of sludge building up faster - where leaving it alone would burn more oil but should keep the system cleaner - not to mention that adding fresh oil when needed can extend the time in between changes a bit - im also assuming you would need to plug the vacuum hose for your vent to work? do you get cel from this?
Last edited by evillecutter : 05/08/2012 at 06:56 PM
I've done it at least five times. I believe twice for a slow flow code, and other times just to keep the small tube clean. It's super easy. My gasket was always sealed to the valve, and I never replaced it yet. Others got a new gasket at NAPA for like $3, so have one on hand. A uni-joint will help with the bolts.
The process is the first question here-
http://www.isuzufaq.com/
If you have no trouble code to start with, you should have after running the engine with the valve off. Just clear it with a code reader.
I tried the breather thing for a short while years ago. I plugged the tube to the intake with a bolt and had a breather filter thing on the hole. It didn't reduce oil use for me at all, so I went back to the stock PCV valve.
It should not pass inspection with a breather like that, but it would be easy to change back just to pass.
Mark
not throwing a code now and do not want to anytime soon if at all possible so i think i will probably just stick to using the stock pcv -i cleaned it out with carb cleaner it seems to be working just fine and looks in good shape - plus i dont use that much oil so its not that big of a deal yet - hey i dont have a code reader so do you have a suggestion of what type/brand/model might be decent/affordable and somewhat user friendly? - and fyi - in indiana we dont have inspections we just blow all out dirty air down to kentucky![]()
so the pcv is an environmental thing then like catalytic converters and the egr etc? sometimes i just wanna take all that s### off and see how it runs - have a check engine light but probably get 30+ mpg or something -heck i bet the oil companies where the ones who lobbied to get the epa to make that crap mandatory in the first place
I've always viewed it as related more to internal vacuum, and a combination of factors not limited only to the PCV valve.
Yes, the main idea behind the PCV valve is based on reducing emissions (burning off oil vapors rather than venting them to the atmosphere), and if that were all that were coming into play where a VX was concerned, then keeping it in place would be best for the VX and the environment. Plus, if oil vapor leads to sludge, venting it would seem to address that problem.
Unfortunately, poorly considered piston and ring design are also factors in this case. Over time, a lack of drain-back holes in the piston bodies leads to accumulation of oil-based sludge on some piston rings, which in turn leads to the piston rings creating even MORE vacuum than originally intended for on the intake strokes, which in turn leads to even more oil vapors being drawn into the cylinders via the intake and PCV systems. In short, a vicious cycle.
Maybe it's simply a question of catching it before the cycle ever get's started that accounts for whether a person has oil usage even if using a breather filter instead of the stock PCV system, maybe not, but I'd personally rather not risk it. Can current piston/piston-ring build-up be eliminated (Seafoam, etc)? Probably no way to really tell short of engine disassembly, but some here seem to have had some success trying that too.