The Stovebolt Site Forums The Shop Area Engine Shop An experiment for the PCV system...

Thinking about the whole PCV setup I found myself wondering what was going back into the engine. Water? Of course. Oil? Some. Gas vapors? Maybe. I'd expect a few gas vapors. Combination of all that? I'd put money on the idea it could be a fairly nasty soup. Possibly corrosive. So as soon as I get to the hardware store to get a couple of fittings, we're going to see what happens when we put an oil/water separator into the PCV line. You can see in the images below the inexpensive one I bought for this. More to follow...just wanted to let you know and also to see if anyone has already done this. If you have, I'd be interested to know what happened. It is my expectation we'll be left with pretty much clean air being fed back in and if that's the case it may open up some other possibilities.

Will be following for results!

Cool idea. It’d be nice to see what that separator captures….on an engine in excellent condition, and also an engine with significant blow by.

My engine fits into the latter. Difficult for me to explain, but the engine actually ran BETTER after added the PCV. Maybe the worn rings seal a bit better with pressure being relieved from the crankcase?

I've sampled crankcase gases with a 4-gas exhaust analyzer. Lots of CO2, and some unburned hydrocarbons, mostly. Very little carbon monoxide, and just about "normal atmosphere" O2 levels. I've also used an exhaust anaalyzer to test the vapors in a cooling system for CO and hydrocarbons, looking for head gasket leaks. Just be VERY careful not to suck up coolant into the tailpipe probe when you hold it over the radiator cap opening- - - -it severely damages the sensors in the machine if you do!
Jerry

Thanks for the input. Just trying to think outside the corral down here...or the pigpen, depending on your point of view on PCV stuff. We ought to see in a few days.

That I couldn't say...I wouldn't think the rings would be providing more compression but I guess it could happen. I might be inclined to think you were running on the lean side and with the PCV you've richened things a bit. Maybe (hopefully) we'll see. My engine is in good shape so that can be one end of the scale.

Suspect it's going to trap lots more water vapor in the humid southeast (including Dallas) than it would here in the Mojave desert. And much less in winter because cold air holds less moisture than warm air. Would be interesting to compare the amounts between say, July and January. That is, if you plan on monitoring year round.

Jon - Where did you get the little separator? I could plug one into my system pretty easily.

I got it on Amazon

https://www.amazon.com/dp/B0CD1T1PJL?

It was a bit less than $10 when I bought it but it is still pretty cheap.

Skooter, yes...humidity in Dallas is almost never low. Due to the massive concrete heat island effect we get only occasional freezes and due to the lakes that ring the city it is as humid as it can be all the time. This morning it is 90% already. We'll see.

Well between taking care of grandkids I installed the separator. Running the engine between 20 and 25 minutes left nothing inside the canister. So at this point I suspect different things. One…the separator needs more airflow (than 18 inches of vacuum) to work. Two…my engine doesn’t put out enough blow-by. Doubtful but possible I suppose. My engine was rebuilt using the least possible factory settings and hot with carb open produces compression of 145 to 150 psi per cylinder. Three it needs more time to reveal results. I’ll keep an eye on it and see.

I'll bet there's a fair amount of pressure loss across that since it's designed for air compressor lines. In that application a couple PSI loss isn't a big deal, but compared to 18 inches of vacuum, that would be significant. It's probably restricting flow to next to nothing thru the PCV system. Guys I know have routed the crankcase vent line into a 1 liter soda bottle and caught some oil and water that way but the rest discharged to atmosphere. I suppose you could do something similar in a larger container that would let the vapor condense and drop out before getting back into the intake manifold. Maybe a cyclone separator type device would work.

Kevin I thought the same thing but it is open. I sort of suspect there is a valve or maybe a spring loaded flap that would be engaged above a certain pressure (vacuum) level. Don’t know yet. Some of the HVLP guns as you know operate on pretty low pressure so this might not work with those either.

Maybe need an actual oil catch can?

Don’t know, really. First I have to figure out how to make it remove oil and water from the air.

Water tends to evaporate under vacuum, so you might not end up trapping much moisture.
Jerry

I am using a PCV valve on my 69 Nova , 250ci engine - and, using an OIL CATCH CAN , also.
I have a CLIFFORD V C , with my Oil Cap / Breather mounted in the front stock (standard) Hole. My PCV valve is in the rear stock Hole.
I do / have gotten some "junk = OIL " in my catch can, before. I have not had this can mounted very long ; and have checked it a few times. IT seems to be working , catching that "junk" , before
"entering my carb" . I'm now thinking that I will start (kinda) keeping a 'record' , of when I check "the can & how much JUNK that I get". I do have some pictures - both of mounting the can onto my engine . . . . .
I just have NOT got this "posting pictures" - thing 'working' - yet.
I ALSO bought the : M E Wagner DF - 17 , adjustable PCV valve , and on their WEB Site (Customer's Rides) , they all seem to be using or adding OIL Catch Cans , onto their cars. So, I added one onto my car.

I have checked inside my valve cover . . and, yes , I do have a Baffel , there.
So far, I like having the 'catch can' . My 250 L 6 runs good, and basely is still stock (insides) , with just "bolt-on up-grades" .


jim

I have tried a picture . . it says my file is too big - - - ?

I'm a little confused about all the emphasis on a PCV system. It works- - - -why get obsessed about what it does, or why? It's far more efficient than a road draft tube, and for the tree huggers who get OCD about their "green" agenda, it keeps all those nasty crankcase emissions contained. When the Clean Air Act of 1968 was implemented, it mandated "closed" crankcase vent systems, which included filtered air into the crankcase, and vapors had to be cycled through the intake and burned with the fuel mixture. One ununtrended consequence of all that legalese was almost doubled engine life since dust and debris was filtered out before vent air got to the crankcase. Abrasive wear was dramatically reduced. The tree huggesrs' concern that unless crankcase vaports were restricted all their kids would be born naked didn't improve, however!
LOL!
Jerry