Pcv or not to pcv?

[Swearbody]

So....My passenger rocker cover is sealed up tight. As in it has a push in oil cap and no venting to the air breather. Perhaps this is contributing to something as it has no way of pulling in air from the passenger cover like OE. Im gonna pull the cap and replace it with a breather/filter and see if that helps.

 

[82sbshortbed]

I have a homemeade catchcan left over from an old turbo build. I can use it but im thinking thats just a bandaid for whatever is causing the blowby/pressure. I dont know though, just thinking it shouldnt happen unless something is fkd up. Im gonna try running a new pcv and then give it a day and check the intake for oil...if there is oil present ill install the catchcan. I also have a three way pcv i could try that closes under boost/pressure @1/2 bar but i dont know how much pressure is generated by the crankcase or how much flow is recommended, so im afraid it may cause a backpressure issue in the crankcase if it closes too early

Yeah I wish I could help more but, I sure wouldn't want that oil to be sucked back into the intake. That just seems like a lot. Wonder if you just put another breather on it like I've got on mine.

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You can barely see it on driver's side. That would keep it from being sucked into intake. Like I said idk for sure is why I started the thread.

 

[82sbshortbed]

So....My passenger rocker cover is sealed up tight. As in it has a push in oil cap and no venting to the air breather. Perhaps this is contributing to something as it has no way of pulling in air from the passenger cover like OE. Im gonna pull the cap and replace it with a breather/filter and see if that helps.

That will definitely help. It needs to breathe. Think you're on to something there.

 

[Swearbody]

Yeah I wish I could help more but, I sure wouldn't want that oil to be sucked back into the intake. That just seems like a lot. Wonder if you just put another breather on it like I've got on mine.

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You can barely see it on driver's side. That would keep it from being sucked into intake. Like I said idk for sure is why I started the thread.

I almost bought one at advanced yesterday. I know you can run em that way but I want to make sure I dont have bigger problems first. Gotta get one for the passenger head anyway since ive realized my passenger rocker cover has no venting "sealed cap" to let air into the crankcase and circulate. This is a block with no vent tube so Im leaning heavily towards a working pcv system over a vent/filter because im afraid of excessive crankcase pressure blowing seals. But really im there with you....I only know what I know and thats apparently just enough to get confused.

 

[DoubleDingo]

Positive Crankcase Ventilation is a good thing to have installed and working properly. Definitely a yes for whether to do it or not. As far as examples go, I'd follow what GM did on the newer squares, not the old draft tube stuff back in the day.

I have always had a pcv valve on the driver's side, and tube going to the air cleaner on the passenger side.

 

[Rusty Nail]

.....

*clocks out*

 

[Vbb199]

This is a pretty intense discussion about a crank case vent valve.

 

[82sbshortbed]

This is a pretty intense discussion about a crank case vent valve.

I'm loving it lol

 

[SquareRoot]

.....

*clocks out*

Off to daydream and drool over VORTEC heads. Nighty night Rusty

 

[Michael Benardo]

Uhhhh....no. Its not that complicated. Its the movement of the pistons that create pressure in the crankcase. You don't blow gaskets on sealed engines if your creating vacuum.

I never said you will blow gaskets, I said you are working against the movement of gases in the crankcase.

 

[Frankenchevy]

I never said you will blow gaskets, I said you are working against the movement of gases in the crankcase.

While I’m not disagreeing with you (because I don’t know enough about it), it is interesting that another member mentioned that his factory sticker shows it routed in the other direction.

 

[Michael Benardo]

Hell yeah guys> i am dealing with pcv issues at the moment so this is a great thread. I had a horrible howl coming from my carb i blame the pcv for,"tested confirmed".
I ran it yesterday with the pcv
"venting" to atmosphere and wound up with a ton of oil on top of the engine. Blew right out the pcv valve on wot pulls.
Does anyone know how much oil should escape the pcv when hammering on it. I know it vents vapor but ive never seen one pump oil from it. Had to be 1/8-1/4 quart, and thats just what was left on the motor. Surely that much oil doesnt get pushed into the carb/intake every wot pull? UNless I have hella blow-by on this newly built motor. I do have baffled rocker covers and using a high volume oil pump if that matters.
Also i had smoke," like rings bad", when I would WOT before unhooking the pcv from carb...now I dont; So I know a ton of oil was getting into the intake every hard pull.

Is your pressure relief valve opening at a normal oil pressure? If your pressure is super high, you could have excessive oil delivered to the rockers, which could cause the problem you are having. Another possibility is broken rings on one or two pistons, or all the end gaps aligned with each other instead of staggered. Lastly, if you are using dirt-cheap motor oil, it can foam at high RPM and blow out the breather.

 

[Michael Benardo]

While I’m not disagreeing with you (because I don’t know enough about it), it is interesting that another member mentioned that his factory sticker shows it routed in the other direction.

That's why I said, "unless your diagram shows otherwise".

 

[Frankenchevy]

That's why I said, "unless your diagram shows otherwise".

Right I get that and I can almost guarantee that your knowledge in the matter far exceeds my own—I’m just curious why they’d suggest a routing that counteracts the vacuum dynamics of the crankcase.

Maybe there’s something they know that we don’t, or maybe the theory that one valve cover has greater vacuum under it than the other may be an old mechanics tale...

Again genuine curiousity not being argumentative, because unfortunately my brain has a tendency to latch on to certain things until it’s satisfied. I think I’ll try putting a vacuum gauge in both grommets to see what I come up with. I believe my engine would be a good test subject because it pulls over 22” at idle or around 26kPa.

 

[Rusty Nail]

Same theory as to why the gas filler door is on one side versus the other.

Huh?
Do tell!