PCV=Vacuum leak
 

On a 91 Camaro I just bought...with a 5.7

There is a chrome breather on the passenger-side valve cover and a PCV hooked up on the front part of the driver side valve cover. There is ALSO on the driver side valve cover, a rubber hose on the back part of the valve cover that is about 9" long...it doesn't connect to anything and is open.

The previous owner said it is a breather too.

It occured to me that this is a big vacuum leak, right? If there is a PCV on the same valve cover as a breather, that is a vacuum leak and could be a source of oil consumption?

Does this make sense?

A PCV is a controlled vacuum leak whether the hose is connected or not. Don't leave the hose open as it can suck debris into the engine as it's unfiltered.

That I am aware of...

I have seen either a breather on each side...or if a PCV is used, the breather is on the other side and the air is pulled through the engine supposedly from the breather on the other side (if no leakage past the rings occurs...

This current setup I have never seen...

Someone got lazy, didn't know or didn't care.

There should only be two opening in the valve cover on the driver side. One for the PCV valve which is ported to the intake manifold and one for the oil servicing cap. Are you sure that 9" hose doesn't come off the back of the plenum and go to the power booster on the firewall.

Hey Trickster...

I really do know how it is supposed to be hooked up...;) Fair question though.

Basically this car was a Lo3/700R4 car that was converted to a 5.7 tpi/T-5 car using a DFI 6 setup.

Honest to G o d though, there is a hose coming out what should be the oil service cap...like they took a valve cover with only a PCV type hole, and drilled another hole in one of them, then stuck a breather hose in it.

The $10,000 question still is though...is this considered a big vacuum leak? It is too late for me to be playing with the car, so I will find out tomorrow night after work...just curious with the theory though as I have never seen it routed quite like this...

Thanks for any input...

Adam,
Is there a oil servicing cap on that valve cover? If it doesn't, it sounds like they took a spare valve cover from the passenger side and modified it. As far as a vacuum leak being there, yes definitely. That is supposed to be a closed system and any openings in it allow more air into the system.

AHHAHA!

I thought so ;)

There is NO oil service cap on either valve cover...they look like stock breather side covers, with the driver side modded(I know from my GTA 350 parts).

The sad thing is that I have worked on quite a few engines...and two knowledgeable car guy friends (not like that kind of friend ;) looked at the car too and didn't really notice it.

The metered air is supposed to come THROUGH the engine and from the breather, so the way it is set up now, it SHOULD be a big vacuum leak.

I promise to post pics as-is...before I change anything...tomorrow. And tell a before/after story if it changed how the car runs...

:hmmm: Does this mean I win the $10,000.00?:lala: :lala:

That depends on if it helps the car run better...

And yes, though the payout is in Iraqi Dinars...the infomercials say they should skyrocket in value sometime. :) :lol:

After reading the way you described it, I assume it was one persons way to make a crankcase evac system. I know most all of us do this with our carbed motors street/strip, but dont know if it'd work well with the computer stuff? I know alot of guys will also take and run a -12 fitting in the fuel pump block off plate and install a -12 fitting in the front of the valve cover and run a hose betrween the 2 to help equalize the pressure on the top and bottom of the motor.

As far as the evac system goes, for street driving we've always had to unhook 1 side. With both hoses hooked the the headers it draws too much vaccum and starts to pull oil through the lines-even with the baffled inserts and dumps it into the collector causing the smokey effect when driving. BUT, it is a sure fire way to keep these sbc from leaking oil.

Unfortunately...pluggin the vacuum hose to the PCV valve didn't help anything.

Also, when the engine warms up, I am getting vapors/smoke like crazy from the breathers...

it burns oil all the time...and I got a discount with the idea that I would have to replace the engine...I believe it is due...

I have a few more things to try though...

If you get blowby through the breathers with the PCV hooked up, the engine is spent, period.