pcv really need 2 vacuum lines?

[ronstang94]

i searched and found some talk about it, but i didnt find a good answer

So, does the pcv really need two vacuum lines?

Im trying to use as few vacuum lines as possible.
and as short of vacuum lines as possible.
so there is only as little clutter as possible.

it seems like maybe there are 2 lines (one located on the bottom) to allow blow-by (oil) to drain back down into the block but I dont know.

Thank you

 

[HISSIN50]

PCV flow is bi-directional. The PCV valve only allows air to flow one way, so the other hose completes the circuit. It's needed.

 

[nmcgrawj]

I thought the PCV valve sits in the lower intake in a stock type setup? Did you or the previous owner change that?



I could have sworn that the pcv only has 1 line on top of it...the bottom of it is in the lower intake. But i could be wrong...its been a couple months since i had my motor apart.

 

[ronstang94]

Hissin, I trust that you are right

but i dont get it.

arent both of the vacuum lines going to the intake from the pcv doing the same thing? sucking air through the pcv into the intake? or is one doing something different?

thanks

 

[nmcgrawj]

the air goes from the crank case/lower intake to the upper....you dont need 2 lines to allow this. Is your valve not sitting in the lower intake?

 

[ronstang94]

the air goes from the crank case/lower intake to the upper....you dont need 2 lines to allow this. Is your valve not sitting in the lower intake?

sorry, i think you are confused about what im saying. it comes out of the crankcase at the lower intake manifold into one vacuum line. it then T's off to 2 vacuum lines, both of which connect to the upper intake manifold.

Im installing a performance intake and am trying to simplify all of the vacuum lines.

thanks

 

[nmcgrawj]

No I fully understand....although my late night posts may not make it seem that way

all lines see the same vacuum...so you only need 1 line going to it. This by no way affects how the valve works.

 

[HISSIN50]

And I misunderstood too. I thought you wanted to eliminate the line from the oil filler to the air-inlet.

In terms of just dealing with the PCV valve hose, I can't think of why you couldn't just have one line instead of two (regarding at the rear of the engine where it splits into two lines to the plenum).

 

[cjrpony]

I am running the Edelbrock RPM II intake and only have the one line hooked up. I haven't had any issues yet.

 

[revhead347]

PCV valve is just one line to the intake. If you buy one from the autoparts store, it comes with a rubber T on the top for use with different applications. Someone must have not known to pull that T off for Mustangs.

Kurt

 

[Beasty306GT]

does it matter which vacuum line..meaning there both different sizes on the pcv valve....should it be on the larger one or the smaller one..reason i ask when i installed my new motor i used the smaller one and i got a slight oil leak from the rear main arean..wondering if it should be the larger one

 

[revhead347]

The T is suposed to be pulled off completely, and you use the single 3/8" hook up that remains on the PCV valve itself.

Kurt

 

[HISSIN50]

We're talking about the Tee on the driver's side of the intake (where the PCV valve line splits and goes to the underside of the plenum and to the driver's side of the plenum), not the two nipples on the PCV valve itself.

 

[ronstang94]

Thanks for all of the responses. Nice to have a definitive answer.

got all of the vac lines figured out, intake manifold installed, and then ran into some problems

EGR tube too short and broken fuel line
but thats another thread, lol

 

[Beasty306GT]

on mine i got the pcv valve going to the bottm of the intake...i got a trick flow upper and lower..should i install a tee right off where it come off the firewall manifold that goes to the upper intake

 

[wytstang]

We're talking about the Tee on the driver's side of the intake (where the PCV valve line splits and goes to the underside of the plenum and to the driver's side of the plenum), not the two nipples on the PCV valve itself.

Here's a picture reference of what JT is talking about (for future references/searches)

 

[nmcgrawj]

Bingo. ^