breather or oil cap?

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Abodysrule

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Perhaps this is well-covered already, but I'm wondering if one runs a PCV valve on the valve cover, and there are two holes, what does one put in the other hole, a breather or an oil fill cap? Some say don't run a breather with a PCV on the same valve cover, others say do it. What's the story? I don't mind running a breather or an oil fill cap, but is one more appropriate than the other? It'll be a 360 magnum, throttle-body injection four barrel, if that matters.

Thanks,

Brian
 
Oil cap on valve cover with pcv valve, breather on the other valve cover.

Cross flow ventilation
 
My car from factory has oil cap on the right side with the breather filter and the PCV vale by itself on the left valve cover.
 
OK, so you run a PCV on one valve cover and not the other? So one valve cover has a PCV and an oil cap and the other has a breather and an oil cap, right? OK to run the PCV line via a catch can?
 
The PCV is the only hole on the left Valve Cover ! On the right one is where the oil filler cap and Breather filter are at.
 
PCV opposite of breather so air crosses thru the engine to get out unspent gases. If not you'll carbon up your motor inside.
 
hcarr said:
The PCV is the only hole on the left Valve Cover ! On the right one is where the oil filler cap and Breather filter are at.
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OP has valve covers that have 2 holes on one side

I suspect aftermarket like this.

Screenshot_20221201-134546.png
 
hcarr said:
My car from factory has oil cap on the right side with the breather filter and the PCV vale by itself on the left valve cover.
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That sounds wrong. You need cross flow to take care of both cylinder heads and valley. Can cap fit the breather hole? Maybe someone swapped them
 
pishta said:
That sounds wrong
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I think what he is saying is

Breather/ oil filler is on one side and the PVC is on the other side.

Right vs left is ambiguous.

My 67 dart 273 has breather / oil filler on the drivers side and the PVC on the passanger side
 
Reread the guys post and it was a run on sentence that now makes sense if he's saying the pcv is one side and filler cap/breather is on other. You just need cross flow whatever the combo is. And historically you should run the breather on the front and the filler on the back on an inline motor.
 
Yeah, my valve covers have two holes each, so I'd do PCV plus filler cap on one side and breather plus filler cap on the other side.

Regarding inline 6's, would one have a PCV on one end and a breather on the other end? How does a single valve cover do cross-flow or is that even possible on a slant six?
 
Hi Everyone!
I have Mopar valve covers that only have one opening per side. Knowing that I’m running a PCV valve on one side, should I use a breather for the other side (doubling as my oil filler) or should I use a closed off oil cap?
I seem to be getting some oil blowback coming from the breather I am currently using.
Thanks for the help!
3CF3DAF7-A942-4786-AF6E-32C98C66D4F4.jpeg
 
Monstro_bjj said:
Hi Everyone!
I have Mopar valve covers that only have one opening per side. Knowing that I’m running a PCV valve on one side, should I use a breather for the other side (doubling as my oil filler) or should I use a closed off oil cap?
I seem to be getting some oil blowback coming from the breather I am currently using.
Thanks for the help!
View attachment 1716038212
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A pcv on one side and some kind of breather cap on the other. The breathers usually double as a oil fill cap.
 
toolmanmike said:
A pcv on one side and some kind of breather cap on the other. The breathers usually double as a oil fill cap.
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Appreciate the knowledge.

If I am getting some oil coming out of the breather, is a condition of a bigger issue? Just wondering, as that’s why I was thinking of closing that side off completely.

Thanks again.
 
Monstro_bjj said:
Appreciate the knowledge.

If I am getting some oil coming out of the breather, is a condition of a bigger issue? Just wondering, as that’s why I was thinking of closing that side off completely.

Thanks again.
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Does it have a baffle in the cover under the cap?
 
toolmanmike said:
Does it have a baffle in the cover under the cap?
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The valve cover has no baffle. The breather cap itself looks like it has a baffle but would have to look at it a bit more closely. It’s something very similar to this:
66E470DB-A078-4FA5-98FE-604E8688A250.jpeg


Should I be using a different type of breather?
 
Monstro_bjj said:
The valve cover has no baffle. The breather cap itself looks like it has a baffle but would have to look at it a bit more closely. It’s something very similar to this:
View attachment 1716038231

Should I be using a different type of breather?
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Probably the only kind you can use. What do the underside of the covers look like? You need something like this. Read the description.

1674417355852.png
 
toolmanmike said:
Probably the only kind you can use. What do the underside of the covers look like? You need something like this. Read the description.

View attachment 1716038233
Click to expand...
Gotcha. I was thinking of changing the style of breather to see if that would help with the oil issue but wasn’t sure if that would make a difference:
DDB9AB66-FAC7-49F8-8AA6-0894264B1E76.jpeg


8178B3A9-C848-4D84-B531-3463E7D165C4.jpeg

Not sure what the underside looks like but there definitely isn’t anything like that already there.
 
Monstro_bjj said:
Gotcha. I was thinking of changing the style of breather to see if that would help with the oil issue but wasn’t sure if that would make a difference:
View attachment 1716038239

View attachment 1716038240
Not sure what the underside looks like but there definitely isn’t anything like that already there.
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That may be worse.Those are often used on stock car engines where there's a lot of blow by and who cares if it leaks. LOL
 
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