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OMG, does anyone know the right way to use a PCV system?!

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Old 08-25-2008, 09:57 PM
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Default OMG, does anyone know the right way to use a PCV system?!

im still eating oil on my 416 and its driving me nuts...here is my set up right now...


intake capped
catch can going to the LS3 valley cover. this line is "T"d and goes to the valve cover. so catch, to valve to valley.
other line has a breather on it for pressure

can this be wrong and pull oil through the piston rings? i get very little oil in the catch can and am going through about a quart every 300-400 miles...

help me here before i run thr C5 off a cliff
Old 08-26-2008, 07:12 AM
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What heads are on the car? On some heads the intake rocker bolt goes into the intake runner and you if you dont use thread sealer on the rocker bolt, you will get an oil burner.

Or if the motor is very new, then you might have a ring seat problem, or it could be the rings werent installed or clocked properly.

Or maybe valve stem seals.

Hope it is an easy fix for you.
Old 08-26-2008, 11:11 AM
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If you plant it to the redline then coast all the way to pretty much idle, then floor it again do you get burnt oil smoke out of the exhaust? If so it could be a piston/rings issue. Was with my old motor.
Old 08-26-2008, 02:40 PM
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L92 heads and L76 intake

and yes, its on decel
Old 08-26-2008, 02:42 PM
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what type of thread sealer should I use?
Old 08-26-2008, 02:46 PM
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red loc-tite.
Old 08-26-2008, 03:19 PM
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As said if its a new motor it could bed in, my motor which i bought as a used item with no more than 2k miles on, was i feel put together with a mis-match of components, the pistons rocked far too much and this was the root of the problem and was never going to hold oil. Do you know what pistons/rings and what tolerances it was assembled to? I am no expert but if you give those facts someone who is more qualified might give you an informed answer.
Old 08-26-2008, 03:48 PM
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Originally Posted by lstvr
As said if its a new motor it could bed in, my motor which i bought as a used item with no more than 2k miles on, was i feel put together with a mis-match of components, the pistons rocked far too much and this was the root of the problem and was never going to hold oil. Do you know what pistons/rings and what tolerances it was assembled to? I am no expert but if you give those facts someone who is more qualified might give you an informed answer.
I bought it built from scoggin dickey. all i know is it has a 4.0 bore with manley -2 pistons. no clue on rings. when I asked for a build sheet, it was like i asked them the sqaure root of something. I called them thursday about all this. they said I would get a call back at Monday at the latest....still nothing.

they said sometimes with "these aftermarket" rings, they need 3-4000 miles to seat right?

I am going to do a leakdown and compression test and see whats up. and if its the rings. hopefully scoggin wil back it up
Old 08-26-2008, 05:20 PM
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Originally Posted by VGLNTE1
intake capped
catch can going to the LS3 valley cover. this line is "T"d and goes to the valve cover. so catch, to valve to valley.
other line has a breather on it for pressure
I am definitely not an expert, but if your catch can is hooked to your valve cover, valley cover, and filter, it is not doing anything. To get it to work, you need a vaccuum source pulling on one end of the can. Hook the end you have on a filter up to the nipple on your intake (not the throttle body - cap that). Maybe somebody else can chime in. That is how I have my 403 routed, though, and I am using little oil if any.

-Geoff
Old 08-26-2008, 05:23 PM
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Originally Posted by White_Hawk
I am definitely not an expert, but if your catch can is hooked to your valve cover, valley cover, and filter, it is not doing anything. To get it to work, you need a vaccuum source pulling on one end of the can. Hook the end you have on a filter up to the nipple on your intake (not the throttle body - cap that). Maybe somebody else can chime in. That is how I have my 403 routed, though, and I am using little oil if any.

-Geoff
i have an LS3, so I have no port on the TB. i had it connected to the intake originally and was sucking more oil into the intake.
Old 08-26-2008, 06:29 PM
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Originally Posted by VGLNTE1
i have an LS3, so I have no port on the TB. i had it connected to the intake originally and was sucking more oil into the intake.
Pictures of how its routed? You need a vacuum source, to both help seal the crank case, and to pull on the catch can. You should not be pulling oil through the catch can into the intake unless 1: the vacuum is routed wrong, or 2: the catch can is completely full of oil.
Old 08-26-2008, 08:16 PM
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Originally Posted by VGLNTE1
here is my set up right now...


intake capped
catch can going to the LS3 valley cover. this line is "T"d and goes to the valve cover. so catch, to valve to valley.
other line has a breather on it for pressure
It's needs to be connected to the intake. I would also remove the T and put a breather on the valve cover. I have mine routed like this: Valley Cover>Catch Can> PCV Valve>Intake.
Old 08-27-2008, 05:17 PM
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Originally Posted by edcmat-l1
Pictures of how its routed? You need a vacuum source, to both help seal the crank case, and to pull on the catch can. You should not be pulling oil through the catch can into the intake unless 1: the vacuum is routed wrong, or 2: the catch can is completely full of oil.
do you think this could help the rings seat? or can it be to late?
Old 08-27-2008, 08:47 PM
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Stop messing around with this catch can, do a leak down on the cylinders and see if you have leakage in them i.e. rings not sealed. DO NOT do a compression test it does not tell the true story. If the rings have not seated there never going to there is no magic going to happen at this point. As I stated before read some of my previous post on this issue. At one point I was excatly were your at and my intake was still filling with oil with no lines hooked to it to get oil in there also my rocker bolts had thread tape on them at this point as well. Simple explaintion is when a piston goes to BDC on the intake stroke there is another that is at BDC in overlap and this is when the oil enters the cylinder and is able to travel the great distance it does to get into the intake via piston rock. I'm sorry but you are probaly going to have to tear that dude apart and do some investigating. Crankcase vacuum is a very good thing but any vaccum at all is harder to achieve then people realize. Breathers and catch cans just try to equalize the crankcase with the air you breath that is it. Not one person has come in here and point blank told me or you how much vaccum they have on there crankcase so trust me DO NOT get to much if you find a way to. (modified smog pump or vaccum pump).
Old 08-28-2008, 04:05 PM
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I am doing a leakdown this weekend. Scoggin still insists that it could take up to 3000-4000 miles to seat the rings. by then all warranty will be gone. No wonder they say go that distance
Old 08-28-2008, 04:58 PM
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Originally Posted by VGLNTE1
I am doing a leakdown this weekend. Scoggin still insists that it could take up to 3000-4000 miles to seat the rings. by then all warranty will be gone. No wonder they say go that distance
I've read, and heard from others thta it can take that long also. I just put a 427 in my GTO and that's what my manual said also on mileage. It also said not to use synthetic until after 5k because that will affect how the rings seat also.
What oil are you using?
Old 08-28-2008, 05:13 PM
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just using regualr mineral oil. Valvoline 10W 40. Scoggin just said to route the PCV valley straight to the intake for the PCV system
Old 08-28-2008, 05:14 PM
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Originally Posted by 05JUDGE
I've read, and heard from others thta it can take that long also. I just put a 427 in my GTO and that's what my manual said also on mileage. It also said not to use synthetic until after 5k because that will affect how the rings seat also.
What oil are you using?
how many miles is on yours? and how much oil were you eating?
Old 08-28-2008, 05:23 PM
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I've got about 2k on mine so far and I've used 1qrt. I am gonna keep running it until it slows down a bit and then change to synthetic between 4k and 5k
Old 08-28-2008, 05:34 PM
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Originally Posted by VGLNTE1
just using regualr mineral oil. Valvoline 10W 40. Scoggin just said to route the PCV valley straight to the intake for the PCV system
My factory motor was run like that.
My current setup with catch-can is run like this:
Valve cover to CAI
Valley cover to lower fitting on catch-can
Intake manifold to upper fitting on catch can

So far it has worked great.

If you are running fron valley cover AND valve cover, to catch can, you are not letting the crank case breath at all. You are pulling vacuum on both sides and have no breathing element in the system. That's what the line from the valve cover to CAI is....or you could plug the CAI port and put a filter breather on the valve cover.


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