C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Crank case vent

 
Old 04-13-2019, 04:17 AM
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jseremba
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Default Crank case vent

I am working on my 1985 4 plus 3. In the FSM on 6E3-139. Th e drivers side valve cover gets a PCV valve. The passenger side says filtered air. Is that another PCV. Or is there a special filter.

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Old 04-13-2019, 07:40 AM
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bjankuski
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It is a hose that connects from the throttle body to the valve cover.
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Old 04-13-2019, 07:44 AM
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jseremba
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I thought it is just a hose. But the FSM said filter I got worried. Thank you
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Old 04-13-2019, 02:57 PM
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ctmccloskey
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On my 1988 C4 Coupe the PCV is located on the passengers side valve cover.
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Old 04-15-2019, 01:03 PM
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cardo0
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Originally Posted by jseremba View Post
I am working on my 1985 4 plus 3. In the FSM on 6E3-139. Th e drivers side valve cover gets a PCV valve. The passenger side says filtered air. Is that another PCV. Or is there a special filter.

Thank you
I don't have a '85 FSM to look at but the crankcase needs a clean air source to make up for what the PCV system takes out. Usually this is a connection between the air cleaner and a throttle body. Easy enough to draw your own picture and trace the air flow from the air cleaner to the crankcase (via valve cover) and the opposite valve cover through the PCV valve and finally to the intake.

To much pressure - from eliminating the PCV - will over pressurize the crankcase and blowout your engine seals. To much vacuum - from isolating the clean air source - will pull dirty air in through the seals and ruin the seals also.

Hope this helps.
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Old 04-15-2019, 02:02 PM
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Hot Rod Roy
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Originally Posted by cardo0 View Post
I don't have a '85 FSM to look at but the crankcase needs a clean air source to make up for what the PCV system takes out. Usually this is a connection between the air cleaner and a throttle body.
To much pressure - from eliminating the PCV - will over pressurize the crankcase and blowout your engine seals. To much vacuum - from isolating the clean air source - will pull dirty air in through the seals and ruin the seals also.
I believe that hose from the air intake to the valve cover has no restrictions, so any crankcase pressure or vacuum would flow freely thru that hose. If the PCV valve is working properly, the clean air flow in that hose would go into the crankcase, but if it's not, there would still be no buildup of pressure, because crankcase gasses would be expelled thru that hose, which would foul up your throttle body.

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