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Discussion Starter #1
So every other vehicle I've worked on has a crankcase breather either with a separate air filter or plumbed into the stock air cleaner on one end and having a PCV valve to the intake manifold on the other end.

I just got done buying half the Lowes plumbing section of 1/2 inch Schedule 40 PVC pipe and fittings to make the extension tube for the breather on the front of the engine as seen in this thread:
http://www.cumminsforum.com/forum/9...should-have-lost-my-puke-bottle-long-ago.html

But I have to ask... Why did they not use a PCV valve like 99% of all the other engines out there... Just plug it right into the intake manifold and burn all the oil vapors up in the engine rather than dumping it all out on the road. The intake manifold is right there. A hole could be put in the intake horn and PCV valves are a couple bucks.


I think my old Ford 7.3L IDI non-turbo also had a weird setup like this where it'd dump the vapors out too.

Seems kind dumb and makes a mess of the engine and undercarriage.
 

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its possible that isn't where your leak is... that's where I thought mine was, so I replaced the filter for it.. turned out my front cover was leaking.
 

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Maybe it has to do with runaway....IDK, just a guess??
 

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Potentially, because putting the vapors/oil into the intake manifold, depending on placement, would run it through the grid heaters. I suppose you could run them into the intake plenum. Regardless, while not probably EPA certified, it was run that way for a reason.
 

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The reason was due to engine performance. The PSD has had, and still does, use a closed crank case vent system. The vent was plumbed back into the intake and run through the turbo and intercooler before hitting the engine. This caused oil to get on the intercooler boots making them susceptable to blowing off. They also had to be oil rated hose or else the oil would eat them. The inside of the intercooler gets all gunked up from the oil residue which kills your cooling efficiency. Lots of guys pulled their intercoolers to wash the inside out and found liquid oil pooled in the bottoms.


Bottom line a closed CCV really is a dumb idea and you're best off to completely forget about it. Look at all OTR and medium duty trucks. They have run an open air crank case vent for years. Only in the last couple years with Tier 4 emissions have they gone to a closed system. Most PSD guys convert to an open air system, even the Navistar version of the 7.3L and 6.0L used an open air system.
 

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Discussion Starter #6
^

Every single gasoline engine has a closed PCV system... Even my lawnmower has a tube from the crankcase to the intake manifold.

I've never seen a gunked up carburetor or intercooler on a gasser. They stick the PCV valve in the intake manifold, after the turbo and intercooler. On the lawnmower it's after the carburetor.


Put it after the induction system, right in the manifold before the intake valves. Engine vacuum will draw the vapors out of the crankcase. It'll stop the oil from getting thinned out by blowby and stop acids from forming in the oil due to water vapor being in there.
 

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^

Engine vacuum will draw the vapors out of the crankcase. It'll stop the oil from getting thinned out by blowby and stop acids from forming in the oil due to water vapor being in there.
These are diesel engines-they don't make intake vacuum which is why they have the PITA vacuum pump. There is no restriction of intake air volume. Furthermore, a warm diesel will run (runaway!) on uncontrolled oil induction.

Keep crankcase vapor/liquid out of the intake stream. If you're environmentally sensitive then catch the vapor/liquid for proper disposal but DON'T feed it back to the engine.
 

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just gonna add, the intake on a turbo diesel is pressurized, so it cannot" suck" in crankcase vapours. and as mentioned its very hard to make a reliable trouble free system than can, GM 6.5 TD has a "tuna can" mounted on the valve cover, it has a different style of function and it is a problem as well.

as soon as you restrict the crankcase system too much its going to blow out from somewhere(seals most likely) even an engine with no blowby caused from leaking past rings, will have lots of air being displaced in the crankcase because of the movement of the pistons moving up/down.
 

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Discussion Starter #9
These are diesel engines-they don't make intake vacuum which is why they have the PITA vacuum pump.
That's one thing that's always confused me...

Everyone says an engine is a big air pump... ALL engines move air, gasoline, diesel, jet engines... All air pumps... The more air you move through them, the more power they can generate, hence the big exhaust modifications, turbochargers, intakes, BHAF... etc... They all increase power...

So if an engine is moving air, it's gotta create some kind of intake vacuum.

The intake sucks in air, hence why we have an air filter otherwise, it'd suck up dirt as well. What else sucks up dirt? A Vacuum does.

Why do we have an air filter if the engine is not sucking in air?



I'm not too concerned about oil leakage now, because I put on a buncha PVC pipe that goes behind the engine... I just don't like having half the Lowes plumbing section under my hood.
 

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There is no throttle plate in a diesel engine. (this is generally speaking)

The vacuum is created between the cylinders and the throttle plate. Just like in a gas engine, when it is at WOT, there is no vacuum. No restriction to create one.

Ryan
 

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Put it after the induction system, right in the manifold before the intake valves. Engine vacuum will draw the vapors out of the crankcase. It'll stop the oil from getting thinned out by blowby and stop acids from forming in the oil due to water vapor being in there.

I see what you are trying to say, but you got to remember our engines have a low area of pressure for what, 1-2 seconds off idle, then are boosted the rest of the RPM range.

To me a system like that is pointless on a boosted diesel engine. You would maybe get some vapour into the intake at idle, but once you start building boost then what? Have shut off solenoids and valves to stop boosted air from pressurizing your crankcase?
 

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Discussion Starter #13
I see what you are trying to say, but you got to remember our engines have a low area of pressure for what, 1-2 seconds off idle, then are boosted the rest of the RPM range.

To me a system like that is pointless on a boosted diesel engine. You would maybe get some vapour into the intake at idle, but once you start building boost then what? Have shut off solenoids and valves to stop boosted air from pressurizing your crankcase?
Something even easier and simpler... A check valve.
The same thing a gas engine uses in the PCV system... That's all a gas engine's PCV valve is, a big check valve.

There's turbocharged gas engines too y'know.
 

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Bush_242
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ok, new guy question. and this is why i need a gopro camera so i can see this . is my 99 cummins blowing crank case vent oil vapor out when im driving(during boost pressures) or just at idle? cummins sells this product, but im still worried about what was previously stated which is too much restriction, and building pressure to come out of the engine somewhere else.

Clearing the Fog with Crankcase Ventilation

ive seen people make something like what they sell at puredieselpower.com or whatever, just tap into a metal cylinder and but a breather on it. any suggestions. i appreciate it. text me if u can, im always working on one of the trucks haha. kain 8473448033. thanks guys
 

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Bush_242
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oh and also, im not going to route the blowby back to the engine or add it back to the crankcase, but why is it so bad to do? what happens to the oil once it blows past the rings?
 
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