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Negative Crank Case Pressure


Michael Savage

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A buddy had a thought today since positive crank case pressure is bad and negative crank case pressure is good.

 

If you connect the PCV hose from the intake hose to the rear valve cover if you connect it to the rear valve cover to the hose the brake booster is on would that create negative crank case pressure? And would it be a good thing?

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A buddy had a thought today since positive crank case pressure is bad and negative crank case pressure is good.

 

If you connect the PCV hose from the intake hose to the rear valve cover if you connect it to the rear valve cover to the hose the brake booster is on would that create negative crank case pressure? And would it be a good thing?

Draw a diagram. I can't figure out what you're trying to explain.

 

First Guess: Connecting a PCV system to a brake booster hose is going to be very bad news.

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Basically on a 3100/3400 leave the front valve cover PCV connected to the top of the intake behind the Throttle Body. Connect the rear valve cover to the intake to create suction on the Valve Covers/Crank Case. A buddy said something to me about that tonight and I had to post it on here and see if that could cause negative crank case pressure and if that would be a good idea. Also give me a minute to draw the idea he had.

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If you connect that rear hose to where the Brake Booster Hose connects by useing a Y splitter could you create negative vacuum and would negative vacuum be a good or bad thing?

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that would probably create a vacuum in the crankcase. unfortunately, it would be directly tied to manifold vacuum, so periods of high vacuum(idle, overrun) will have decent crankcase vacuum but during heavy throttle, that vacuum would no longer exist.

 

basically, it operates in reverse of what you would need it to.

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Okay so it would be a good idea if you actually could acutually get it hooked up rite, because it would work just like normal but with a bit extra vacuum.

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depending on how much restriction there is between the intake and the crankcase, the crankcase itself can act like an extension of the intake plenum itself as well.

 

that....... may or may not be a good thing.

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Lol basically his idea sounds good in theory, but could end badly or really good?

It WILL NOT end "really good".

 

How much of a disaster it is will largely depend on how much unfiltered air gets pulled in through the seals, gaskets and dipstick tube. You pull enough of a vacuum in the crankcase, you better be prepared to have the valve cover gaskets implode.

 

Overall, this is another idea you shouldn't put too much time or effort into.

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Feel free to delete this thread. I was talking to my buddy about the PCV system and the effects of positive crank case pressure and he suggested this and told me to look into it. I wanted inputs on Kails idea on that. I wasn't sure about the idea so I figured IDE ask you guys. Thanks for the response on this idea of his!

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