pcv ?
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Senior User
Joined: Feb 2010
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pcv ?
so a buddy asked me if you need a pcv or if you could just use a breather instead i said that i know of you need a pcv, he asked what would happen if there wasn't one just one breather for on one side of the valve cover and nothing on the other just sealed, so i don't know what could happen anyone know?
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Joined: Jul 2005
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From: Mountville PA
yes so the vacume in the engine can pull the vapors out theres a more technical thing to it thats its suppost to keep the oil from depositing on internal parts but don't know for sure but I would hook it up
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Joined: Apr 2009
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From: Stanley, VA
Before the PCV system was introduced, cars and trucks used a road draft tube to vent the crankcase. This was a long tube that usually hooked to the rear of the intake manifold or the block itself and extended down to just below the engine. The end of the tube was cut at an angle so the air flow would create a draft and help pull the blow-by out and vent it directly into the atmosphere.
The PCV (positive crankcase ventillation) is basically part of the emission control system but it is much, much better for the engine than the old road draft tube.
You can run the engine without it as long as there is some way to vent the excess pressure that will build up from the blowby but I wouldn't recomend it.
The PCV system helps keep the engine internals clean, reduces sludge and acid build up and also reduces oil consumption.
Without some type of vent you will also have oil leaks at many different points because of the pressure.
You will also see a cloud of blowby gasses coming out of the vent, this is all unburned fuel and oil vapor, aka "polution".
The PCV (positive crankcase ventillation) is basically part of the emission control system but it is much, much better for the engine than the old road draft tube.
You can run the engine without it as long as there is some way to vent the excess pressure that will build up from the blowby but I wouldn't recomend it.
The PCV system helps keep the engine internals clean, reduces sludge and acid build up and also reduces oil consumption.
Without some type of vent you will also have oil leaks at many different points because of the pressure.
You will also see a cloud of blowby gasses coming out of the vent, this is all unburned fuel and oil vapor, aka "polution".
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so my buddy didn't have one and is now puking oil if he puts one now will it stop or slow down the leaks or will he have to replace those seals and gaskets now?
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Hotshot
Joined: Apr 2009
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From: Stanley, VA
If the crankcase wasn't vented in any way that could have caused the problem, but a vent can take many forms. The oil fill cap is often vented. If the valve covers had an aftermarket breather added that could be another form. Even just leaving the oil fill cap off would accomplish the same thing.
Adding a PCV system now will probably not make any difference in the oil leaks. If the seals and/or gaskets are leaking now because of excess pressure, chances are they will need to be replaced.
Adding a PCV system now will probably not make any difference in the oil leaks. If the seals and/or gaskets are leaking now because of excess pressure, chances are they will need to be replaced.
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Joined: Feb 2010
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From: Salem,Oregon
mike, you seem to know about pcv..
so on my passenger side i have my pcv going to back of my carb. . all good
on my drivers side valve cover i have my oil cap but its a sealed one.. now is that okay?
when i first bought it, it was this way but it fell off while driving so when i bought a new one the auto parts guy said that recommend a vented one but i got a sealed one instead.. okay? or should i go vented?
so on my passenger side i have my pcv going to back of my carb. . all good
on my drivers side valve cover i have my oil cap but its a sealed one.. now is that okay?
when i first bought it, it was this way but it fell off while driving so when i bought a new one the auto parts guy said that recommend a vented one but i got a sealed one instead.. okay? or should i go vented?
MSEE
Joined: Apr 2004
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From: Austin, TX
If one valve cover has the PCV valve going to the carburetor, then the other valve cover needs a way for fresh air to get in. The factory setup would have had an oil cap with a hose that goes to a breather filter in the air cleaner. You can get aftermarket breather caps that have the breather filter built in. If you have a sealed oil cap as you've described, then your PCV system is trying to suck in fresh air through your piston rings or any weak seals on the engine (oil pan gasket, valve cover gasket, etc). This is going to cause oil leaks. You need to replace it with a vented oil cap, just like was recommended to you. You can do this with a breather cap, or a factory breather hose setup.
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From: Salem,Oregon
maybe thats why i have a leak on the engine somewhere.. i cant seem to figure out where its coming from either.. damnit..everything is falling apart on this truck! iam 16.. i cant afford to be fixing this with the money i dont have or dont have comin in! ughh
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Joined: Apr 2009
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From: Stanley, VA
X2 on fmc 400
Take your oil filler cap off and look at the underside. If it has holes around the perimeter then it is a vented cap. If there are no holes then it is sealed and should be swaped for a vented style.
Take your oil filler cap off and look at the underside. If it has holes around the perimeter then it is a vented cap. If there are no holes then it is sealed and should be swaped for a vented style.
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