PCV Valve, do I really need to run one? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 02-26-2013, 10:28 PM
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PCV Valve, do I really need to run one?

Currently I'm running a spectre pcv valve on one valve cover and a breather on the other. Would it be bad to run 2 breathers instead, would it effect engine longevity?

currently the motor is a stock 290hp gm performance crate motor. It's installed in a daily driven 1971 Toyota FJ40 Land Cruiser.


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Old 02-26-2013, 10:41 PM
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Are you thinking about running a vacuum pump,or just letting the engine vent w/e it wants out the holes in the valve covers?
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Old 02-26-2013, 11:16 PM
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There is no benefit to disabling the PCV system and plenty of down side,
including but not limited to throwing the idle circuit out of wack.

The PCV is part of the idle circuit.
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Old 02-27-2013, 06:59 AM
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Quote:
Originally Posted by F-BIRD'88 View Post
There is no benefit to disabling the PCV system and plenty of down side,
including but not limited to throwing the idle circuit out of wack.

The PCV is part of the idle circuit.
Apparently one of the issues I'm having is oil being sucked into the manifold then into the combustion chamber. Right now I'm running a spectre baffled grommet and pcv valve running into the front vacuum port of my quadrajet.
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Old 02-27-2013, 07:39 AM
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I had a p.o.s. that did that not calling your vehicle a p.o.s. just mine
I took a longer hose and made a loop.. with the part from pcv to loop an incline..
the oil had a hard time climb'n the loop and the incline let the oil drain back as most pcv dont seal real tight when closed..

cheap and dirty fix..
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Old 02-27-2013, 07:50 AM
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Oil separator

Consider a catch tank. If it starts filling with oil then you'll know where the problem is. If it does not catch any oil, then you'll know its migrating from elsewhere, such as valve guides/seals, intake gaskets, rocker stud threads, etc.
Nolan

http://www.summitracing.com/search/p...perator&ddsc=1
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Old 02-27-2013, 08:37 AM
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Quote:
Originally Posted by 71fj40guy View Post
Apparently one of the issues I'm having is oil being sucked into the manifold then into the combustion chamber. Right now I'm running a spectre baffled grommet and pcv valve running into the front vacuum port of my quadrajet.
Ive never seen a baffled gromet that actually works!! the oil collects on the rubber runs down and is sucked into the pcv LOL they are junk you need valve covers with baffles bellow the breather hole that set away from the grommit .

Jester
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Old 02-27-2013, 09:35 AM
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Originally Posted by painted jester View Post
Ive never seen a baffled gromet that actually works!! the oil collects on the rubber runs down and is sucked into the pcv LOL they are junk you need valve covers with baffles bellow the breather hole that set away from the grommit .

Jester
That's what I was affraid of.
Does anyone know who makes aluminum covers that have baffles?
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Old 02-27-2013, 09:50 AM
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Quote:
Originally Posted by 71fj40guy View Post
That's what I was affraid of.
Does anyone know who makes aluminum covers that have baffles?
SUMMIT, AMONG OTHERS.. even gm
what bolt pattern outer or center?
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Old 02-27-2013, 10:41 AM
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Run baffled valve covers. Even Mr gasket covers are baffled.
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Old 02-27-2013, 02:46 PM
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Quote:
Originally Posted by 71fj40guy View Post
Currently I'm running a spectre pcv valve on one valve cover and a breather on the other. Would it be bad to run 2 breathers instead, would it effect engine longevity?

currently the motor is a stock 290hp gm performance crate motor. It's installed in a daily driven 1971 Toyota FJ40 Land Cruiser.

Pulling oil over the PCV would indicate that either (or both) the PCV is missmatched to the engine, the PCV has failed, there is insufficient or missing oil seperation media before the PCV, the compression rings are damaged, not seated (broken in), end gap too wide, or worn out (any of these results in excessive blow by), the engine is operated at elevated RPMs and high loads (this resuts in high amounts of blow by and lots of internally flying oil which has gotta come out somewhere).

Certainly a compression and a leak down test are in order up front as if the problem is in ring sealing for what ever reason, nothing else will solve the problem so there's little sense in spending a chunk of money on band-aids only to find it's still bleeding to death.

The PCV is intended to remove blow-by products from a normally healthy engine so first this means there's not a lot of blow by to begin with. Secondly blow by consists of compression and combustion gases that get past the rings, for the most part this is a combustable mixture that is rather corrosive when it mixes and circulates with the lube oil so burning it adds a lot of years to the engine's life. The presence of lube oil passing the breathers tells you that either the filter/seperation media is missing or failed in a normally healthy engine or that the engine is not healthy having a serious problem that is producing so much blow by that the seperation media is overwhelmed.

Bogie
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Old 02-27-2013, 04:24 PM
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Most aftermarket SBC valve covers have the PCV hole in the wrong spot on the cover and lack any oil baffling.

The result is:
The PCV hole gets a direct shot from the rockers oil spray. Many many aftermarket parts may look pretty but are of fubar design.
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Old 02-27-2013, 05:15 PM
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Quote:
Originally Posted by F-BIRD'88 View Post
Most aftermarket SBC valve covers have the PCV hole in the wrong spot on the cover and lack any oil baffling.

The result is:
The PCV hole gets a direct shot from the rockers oil spray. Many many aftermarket parts may look pretty but are of fubar design.
I just ordered a retrofit baffle for my valve covers.
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Old 02-27-2013, 06:55 PM
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Try a different valve cover that has baffles. Sometimes the breather/PCV opening in the valve cover is in a bad spot and gets a lot of oil from the rocker arms. The baffles will limit the amount of oil that travels directly into the PCV. You don't want to completely eliminate the system as you need to have some sort of crankcase evacuation system. You could also run a crankcase evac system with breathers on both valve covers with hoses piped to your exhaust. No oil to go into the intake manifold carbon up the plugs. The plugs stay cleaner and the extra gases go out with the exhaust. Not good if you have to pass emissions testing.
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Old 02-27-2013, 07:41 PM
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Quote:
Originally Posted by 71fj40guy View Post
Awesome Land Cruiser!

If you have a alot of blowby the baffled valve cover still won't solve the issue.

OLNOLAN's catch can idea is a good "stop gap" measure until you have the time / money / ambition to address the real issues that are creating the blow by.
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