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Discussion Starter #1
So, about a month ago I added a catch can but returned the output back to the intake. The theory was to remove any luqiuds, but still allow the air to enter the engine.

http://www.duramaxforum.com/forum/performance-upgrades/107144-lbz-pvc-re-route-correct-way.html

When I did this, I cleaned up the previous oil in the line to the inter-cooler and temporally used clear tubing to the catch can so I could monitor the in and out to make sure I was catching everything.

Well....after a couple thousand miles, I haven't caught anything because I haven't pulled anything. Both tubes are clean as a whistle, nothing.

I believe what has happen is that because I mod'd my airbox and removed a lot of the restriction, I've lower the vacuum level for the PCV to the point where there's not enough force to raise and pull fliuds anymore.

So, I think the moral here is that if you have a less restrictive airbox of some sort, and a clean filter, a PCV re-route would be a waste of time and money...I guess.
 

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Its just a worktruck
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Wrong. I had an AEM intake and no PCV re-route and everything still had oil in it. When I did do away with it we had 2 hoses just hanging down in the wheel well. It really saved my ass when the piston cracked.
 

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Discussion Starter #3
Wrong. I had an AEM intake and no PCV re-route and everything still had oil in it. When I did do away with it we had 2 hoses just hanging down in the wheel well. It really saved my ass when the piston cracked.
Well, OK then, if my theory is incorrect than do you have a theory of why I'm not pulling oil anymore? And yes, I've double checked and all my connections are good and there are no vacuum leaks.
 

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Its just a worktruck
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If the lines from the valve covers are not going into the intake tract, no oil will be sucked through them because there is no turbo to create vacuum. A catch can is pointless on a diesel. There will never be anything in the lines once the fitting is removed from the intake.
 

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Discussion Starter #5 (Edited)
If the lines from the valve covers are not going into the intake tract, no oil will be sucked through them because there is no turbo to create vacuum. A catch can is pointless on a diesel. There will never be anything in the lines once the fitting is removed from the intake.
But the line is going to the intake. I've taken the valve cover lines, T'd them and ran them into a catch can. I've then run a line from the other fitting on the catch can back to the original intake tract fitting. The can has no vent, it only has two fittings, an in and an out. There is still vacuum, I've measured it. All I've changed from the factory setup is lengthened the tubing between the 'T' and the intake fitting for the PCV with a sealed catch can in the middle. The catch can just makes a place for the 'fluids' to drop out because it has become a low pressure area in what is otherwise a unchanged system.

Honestly, if decreasing the restriction is not the reason I'm not seeing any fluids, I'd like to hear other theory's.
 

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Its just a worktruck
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Oh. Looks like I'm wrong then. I ASSumed by PCV re-route you meant the line was no longer going to the intake.
My second guess is that the vacuum is less due to the longer/larger tubing and it wont pull the oil out of the heads. But I'm just taking shots in the dark now. I honestly have no clue.
 

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Hang it!...Fire!
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All i know is that mine was pulling all sorts of oil and crap into my intake before i did the re-route, and after there was no more. seems like a win to me
 

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Diesel Junky
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i had some oil in my lines but not any drippage, just did the catch can for looks
 

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Discussion Starter #12 (Edited)
Maybe im thinking wrong here, But I dont see why it would be a bad thing that your not spitting oil anywhere
Totally agree. The object is to keep the oil in the engine. I was just floating the theory that it was because of decreasing the intake restriction.

I did do some testing over the weekend just to see what would happen and I temporly added some restriction to the airbox and sure enough, I got it to pull a little oil. The only problem is that I have no way of knowing exactly how much restriction the stock setup has.

I'm guessing there's other factors also like type and weight of oil. I'm currently running Redline 15w-40 which is one of the only true group 5 synthetic oils and very stable. Also, the more blow-by the more air and oil you're going to pull out. I would say if you have a low restriction intake, a good 15w-40 oil and you're still getting a bunch of oil in the intake, you probably have a lot of blow-by.
 

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Dumb question... but you check the tubes.....

did you check the catch can?
 
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