my 65,327-365, deposited alot of oil in the air cleaner and base a few days ago.referring to the archives, i checked to see if the cannister was in the lifter valley, it was there,and in a very clean condition. have any miracle cures been developed for this condition? thanks in adavnce for your help. greg #32001
-
-
Re: C2: oil in air cleaner and base
I've never heard many stories about that PCV design being problematic. Check that the restrictor fitting in the carb that connects to the hose to the oil fill tube is not clogged.
Duke -
Re: C2: oil in air cleaner and base
What kind of air filter are you using?Comment
-
Re: C2: oil in air cleaner and base
I know this may sound very basic but could the crankcase have been overfilled causing excess splash to "push" more oil vapor out the pvc?
The other reason could be from sitting for an extended period and upon startup there was more "blowby" than normal again causing excess oil to push out the pvc and collect in the air cleaner base.Comment
-
Re: C2: oil in air cleaner and base
Duke,I checked that fitting and it was clean, shiney clean inside, not what i expected to see. Thanks for the tip.Comment
-
Re: C2: oil in air cleaner and base
JOE, my best guess is fram.Comment
-
Re: C2: oil in air cleaner and base
Steve, an overfull crankcase does make sense, but i'm sure it wasn't. I've been driving the car quite a bit lately so it really hasn't sat for a long period of time.Comment
-
Re: C2: oil in air cleaner and base
Greg:
The easiest fix would have been, just maybe, you were using the original oiled foam type air filter. Since you are using a modern paper element, then re check the 90* orifice fitting on the left side of your Holley 2818 carburetor. The hole should be .090" diameter. If that checks out AOK, then I would then believe that you are getting excessive blowby due to worn valve guides/seals, and/or rings.
JoeComment
-
Re: C2: oil in air cleaner and base
Put a piece of rubber tubing against the opening in the carb (fitting removed) and blow through it to be sure the carb passaged are clear. The fitting is the most likely thing to clog since it has the restrictor, which I think is .090".
During normal throttled operation when there is signficant manifold vacuum the flow is from the air cleaner to the back of the block and then through the oil fill tube to the inlet manifold via the carb./fitting. The restrictor limits flow at high vacuum. This is the opposite direction of the flow on the '63 systems that use a valve.
During WOT operation, when there is little manifold vacuum, flow can reverse, especially if the engine has high blowby.
I've always wondered why Chevrolet changed the PCV system design to the valveless architecture in '64. The system in my SWC worked fine, but over time, the valve and carb base could see some oil/carbon buildup, though it was not bad, and the all metal valve could be easily cleaned.
Could be that they just wanted a freer flowing system at WOT in case the engine developed high blowby. PCV systems were fairly new back then and I suspect GM was experimenting around with different architectures.
Not sure if they learned much. The PCV system on my Cosworth Vega was HORRIBLE. It constantly flowed backwards (even though it had a valve and was supposed to flow one way) by pumping oil into the air cleaner under high dynamic loadings (cornering) from the fresh air inlet in the base of the block.
Years later I realized that EFI cars do not need valves with an antibackflow feature because a backfire cannot propagate into the PCV system since the inlet system is "dry" above the injectors. The antibackfire feature on your system is the screen in the air clear so make sure it is intact. Without some sort of flame arrestor or antibackflow device on a carbureted engine, a backfire can propagate to the crankcase and cause and explosion.
If finally eliminated the fresh air inlet into the bottom of the CV block. I replaced the line from the cam cover outlet with its valve that routed into the inlet manifold with a hose to the air cleaner that connects to the former fresh air supply, and I included a built in liquid trap. Essentially, the crankcase is now just vented to the air cleaner. It fulfills the "closed crankcase function" by routing blowby back into the engine inlet to be consumed by combustion although it's not considered a "positive" system since only crankcase pressure is available to vent blowby, but it eliminated the oil ingestion problem.
I'd like to take credit for the design, but after first trying my own design and seeing it fail, I just ended up copying the PCV system architecture designed by Toyota for my '91 MR2.
DukeComment
Comment