oil in air cleaner housing

[Daniel D.]

[Ed S.]

Re: oil in air cleaner housing

Had the same problem with a 327 years ago - it was blow-by; compression rings were not "compressing" sufficiently. I was getting some compression pressure into the crank case, that increases the atmospheric pressure well above normal in the crankcase -there only one place for oil to go, up to the PVC valve and into the air filter housing. You have a force on one end pushing and vacuum on the other end pulling - doesn't take much to get some oil up into the air filter housing. Do a compression check, you may find the culprit there.

[Keith B.]

Re: oil in air cleaner housing

Do you have the correct 90* PCV elbow fitting on the carb

[Elliott P.]

Re: oil in air cleaner housing

Daniel, here are a couple of good probablies for you. If you just want to drive and not do NCRS judging, I recommend changing out the factory-proper oiled-foam air filter for an after-market paper filter. WIX air filter #42070 fills the bill (and cheap). Proper after-market GM replacement paper filter is no longer available (except maybe in old stock). If the paper filter stays dry, your problem

[Edward J.]

Re: oil in air cleaner housing

Dan I would start by performing a cylinder leak down test on all cylinders, this should give you a idea on piston ring sealing, excessive blow by can create oil in the air cleaner.If you have never done this you may find some info on this with you tube, you will need a small air compressor to perform the test.

[Daniel D.]

Re: oil in air cleaner housing

Thanks for your replies. Keith, I do have the 90 degree fitting on the carb. And Elliot, I'm using the Wix filter. I will run a compression test. The rebuilt engine runs very strong, so I hope there is not a problem with piston rings.

[Keith B.]

Re: oil in air cleaner housing

But do you have the correct 90* fitting with a restriction orifice

[Daniel D.]

Re: oil in air cleaner housing

Thanks Keith. Yes, it does have a restricted orifice. I took it off, and verified that it is not clogged or dirty. Is it relevant that the oil seems to collect when I'm cruising at relative high rpm for extended time? I assume the carburetor is sucking a lot of air at 3,000+ rpm cruising. Also, I do feel some suction on the crankcase vent pipe, which I think is proper.

[Dick W.]

Re: oil in air cleaner housing

Sounds like the rings have not seated. Going back to the old Doctor of Motors (Perfect Circle Piston Ring book), get the engine warmed up, take it out on the highway, accelerate from 30 to 60 mph, repeat multiple times. Old chrome rings were very hard to get seated. Years ago on HD engines we actually would feed a mixture of Bon Ami and diesel fuel in the intake to get the rings seated.

[Daniel D.]

Re: oil in air cleaner housing

Thanks Dick. For my sake, I hope your's is the right answer . I will run a compression check to see if they are consistent.

[John L.]

Re: oil in air cleaner housing

Sirs
A thought - missing ventilator can under the intake manifold? - I believe it helps separate oil from the air as the fumes are sucked out.

[Joe L.]

Re: oil in air cleaner housing


Daniel------


I don't think you have a solvable problem. Assuming that you're not getting a huge amount of oil in the air cleaner, I believe what you report is, essentially, normal. These early PCV systems were not that great and what you describe is quite common. My original owner 1969 evidenced this exact same problem from day-one. I was NEVER able to solve it. But, I actually gave up trying a LONG time ago.

[John L.]

Re: oil in air cleaner housing

Daniel
Addition to my previous message - the ventilator supplies air TO the crankcase -But if the engine has enough blow by at higher rpms and the crankcase pressure goes positive then oil can get blown into the air cleaner- a leak down test is good advice when you get a chance.

[Daniel D.]

Re: oil in air cleaner housing

Thanks Joe, I wondered if the oil problem might not be uncommon. Especially with the 65 year not having a real PCV valve.

John, I was also thinking about the baffle/ventilator. I do know that it was reinstalled during the rebuild, but is it possible that it was not pressed in tight? I'm thinking that if the fastener bolt lines up, then the baffle must be installed properly?

[John L.]