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Discussion Starter #1
I wanted to come up with a way to re-route the PVC to stop the oil and water from entering the turbo but still properly vent the crankcase. To remove contamination caused by blow-by and water caused by condensation it's important to maintain airflow other just vent.

I came up with this-



I paid $25 for the catch can on fleebay. I got the square one so that I could add baffling if need be, so far I haven't. The clear lines are temporary so that I can see what goes in and out. As it stands, it catchs all the liquids without changing the factory level of crankcase ventilation. Since you use less hose, the cost is really only slighty more. And for those that don't really like the smell of hydrocarbons, it retains the crankcase emissions system.
 

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Im Superrrrr!
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fixed your pic...
 

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Diesel Junky
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looks good, did mine but with a round catch tank and some all thread for mounting.
 

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Everyone on here is against catch cans, most just dump them off the driver side frame rail. Catch can works fine but you will need to check it every so often make sure its not full. Also does it have any type of vent? you dont want a sealed one
 

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Diesel Junky
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sealed would be bad, and i know everyone on here will crtitize a waste of money, but i hate the oil spot in my driveway. so i got this
 

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Mine dumps to the ground and it hasnt had any oil whatsoever, you mostly had oil because the turbo was pulling it out of the valve covers
 

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I believe there are two main reasons for the re-route. #1 was solved, keeping the crap outta the intake. But #2 wold be preventing a run-away in the event of a failure causing large amounts of oil to be pushed out of the PCV valve, making a bad situation worse (probably MUCH worse, where's that pulling truck that did endos in someone's lawn when she ran away :confused: )
I want a simple setup that's effectively the same as this: (This is the engine in my Unimog, breather is nothing more than a filter and downward pointed metal tube.
 

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This may be a dumb ? But I know on gas motors the pcv is drawing air out of the crankcase but there is also a vent that allows air in. Do Dmax's have an air inlet somewhere?
 

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Discussion Starter #9
Everyone on here is against catch cans, most just dump them off the driver side frame rail. Catch can works fine but you will need to check it every so often make sure its not full. Also does it have any type of vent? you dont want a sealed one
Yes, mine is sealed.

I've T'd the value cover ports and ran them into one side of the SEALED can the the other side of the can is connected to the port on the intake that the valve cover ports used to be T'd too.

The system still operates as it did from the factory except when the vapor gets pulled into the can the moisture is trapped in the can. Any blow-by air, be it unburnt hydrocarbons or carbon monoxide still enter the intake.

A vent can would not support and type of vacuum to maintain positive ventilation.

I know most of the members here that have done a PVC re-route just 'T' the valve cover ports and running a hose down to the frame. That would be a open atmospheric vent. The thought with this type vent is that any blow-by will cause a pressure that will vent out the block. This would be fine if your only concern was not to pressurize the block and blow a seal. If you want to make sure that the crankcase is clear of oil contaminating moisture, exhaust, and hydrocarbons you need to have some type of positive ventilation.

In most cases, positive ventilation improves ring sealing which not only increases horsepower, but helps prevent blow-by.

Beside, through I'm not captain tree hugger or anything, if I can solve the problem (which is removing the moisture from the PVC) and still retain the close loop PCV and keep from needlessly dumping hyrocarbons into the atmosphere, why shouldn't we?
 

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I understand your system and that your can is sealed. The can does not change how the system works it just doesnt allow any liquid to enter intake.

So as the engine is drawing on the PCV is fresh air going into the crankcase somewhere? On a gas motor the answer is yes. What about a D'max?
 

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Discussion Starter #11
I understand your system and that your can is sealed. The can does not change how the system works it just doesnt allow any liquid to enter intake.

So as the engine is drawing on the PCV is fresh air going into the crankcase somewhere? On a gas motor the answer is yes. What about a D'max?
You know that's a good question and I don't know the answer. I do know that it comes in somewhere because there is air movement in the stock system.

My theory is that I maintain the stock configuration as close a possible I won't over tax the input, whatever it is. No problem.
 

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The PCV valve is nothing more than a check valve. On stock application the turbo pressure keeps the valve open. When re-routed the check valve will open when needed and release the pressure. Gassers need the vent due to high rpm's. Diesels however don't turn enough rpm's to justify catch cans and an outside source to ventilate the system. In other words the PCV valve is not necessary. Air travels one way through the valve. Unless you are driving through water just hook up hoses to the ports without the valve and let it breathe. PCV was created by the EPA and we all know how well they work.


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Discussion Starter #13 (Edited)
The PCV valve is nothing more than a check valve. On stock application the turbo pressure keeps the valve open. When re-routed the check valve will open when needed and release the pressure. Gassers need the vent due to high rpm's. Diesels however don't turn enough rpm's to justify catch cans and an outside source to ventilate the system. In other words the PCV valve is not necessary. Air travels one way through the valve. Unless you are driving through water just hook up hoses to the ports without the valve and let it breathe. PCV was created by the EPA and we all know how well they work.


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PCV (positive crankcase ventilation) and the PCV valve has been around much longer than EPA. Since the late 1920's motor vehicles engines have had some type of PCV system. Usaully it was simply a breather cap and a draft tube. The draft tube was positioned in such a way that air moving across the opening from either the fan or the vehicles travel would draw a vacuum clearing vapor from the crankcase.

Closed PCV with developed during WWII so that tanks could cross deeper water bodies. Closed PCV system were not used for emission until 1961 in California (of course), the rest of the states 1962. EPA was formed in 1970 under Nixon.

A diesel motor doesn't normally need a PCV valve. A PCV valve purpose is not on-off, but to reverse the manifold vacuum signal. An internal restrictor (generally a cone or ball) is held in "normal" (engine off, zero vacuum) position with a light spring, exposing the full size of the PCV opening to the intake manifold. With the engine running, the tapered end of the cone is drawn towards the opening in the PCV valve by manifold vacuum, restricting the opening proportionate to the level of engine vacuum vs. spring tension. At idle, the intake manifold vacuum is near maximum. It is at this time the least amount of blow by is actually occurring, so the PCV valve provides the largest amount of (but not complete) restriction. As engine load increases, vacuum on the valve decreases proportionally and blow by increases proportionally. With a lower level of vacuum, the spring returns the cone to the "open" position to allow more air flow. At full throttle, vacuum is much reduced, down to between 1.5 and 3" Hg. At this point the PCV valve is nearly useless, and most combustion gases escape via the "breather tube" where they are then drawn in to the engine's intake manifold anyway

The Duramax doesn't need a PCV valve. The vacuum for the PCV system is the differential between the turbo and the air filter. In this case the vacuum level follows throttle level. The more throttle, the higher the differential, the higher the vacuum. A PCV valve to reverse the vacuum signal is not need in this system. I have not taken the housing on valve cover apart but I believe all that you will find inside is baffling and maybe a check valve. A check valve and PCV valve are not the same thing.


Not circulating air through the block leaves the blow-by gases in the crankcase to commentate the oil.
 

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Not circulating air through the block leaves the blow-by gases in the crankcase to commentate the oil.
In stock form the differential between the turbo and air filter is pulling, however small it might be, a vacuum on the crankcase. But for air to be circulated you have to be letting air in somewhere.
 

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So Long Space Cowboy...
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any pics of how you mounted it?
 

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So Long Space Cowboy...
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i hate to ask a dumb question, but what size are the hoses?
 

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So Long Space Cowboy...
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Well thanks! I love the setup! The clear hoses are a great idea! Even if the are just temporary.
I appreciate it. Im definitely going to go with this method on my lmm!

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