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Old 04-25-2005, 01:35 PM
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PCV necessary?

I was just wondering about PCV systems. Is it ok to just have a breather on one of the valve covers or do you need a PCV system. Also do you route the PCV into the aircleaner. My old manager at work who knew alot about cars said it should go through the large vacum hose that the power booster runs on. That seems like it would just create a huge vacum leak. What way is right.

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Old 04-25-2005, 01:53 PM
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Use it... It is not hurting anything by having it on. If you use duel breather caps it is a good chance oil will be sprayed on your valve covers at the end of the week. The valve is there to suck the pressure out of the crank case so in my mind not having sludge inside the engine is a good thing... therefore yes having one is good and it does not hurt performance in anyway...
This has been gone over before.

The hose can run to the air cleaner (common stock set up on older cars)
Or to the carb. which will have a hook up normally in the back towards the diz(on a sbc) to hook into. It can also run into (on later cars) into a emmsions canister. Sometimes there is a common hook up point the brakes may be taking the vacumme off the same palce the PCV valve would use.

Chris
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Old 04-25-2005, 01:54 PM
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The pcv hose should be routed to a large port on the carb. You also need a breather on the other valve cover.
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Old 04-25-2005, 07:26 PM
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breather in valve cover

on my sbc the valve covers have pcv and a vent tube, are there
breathers small enough?
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Old 04-25-2005, 07:44 PM
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Speaking of vacum lines won't teeing in a pcv into the boosters line create a large vacum leak. I mean you will be sucking air in through the vacum line below the venturis so wont this be unmetered air? This is always confused me.
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Old 04-25-2005, 08:52 PM
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no

That's what it's there for.
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Old 04-25-2005, 10:47 PM
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Really. Cause if you were to just take the hose off of the fitting then the car won't run good because its sucking air throught that hole. So then by putting a PCV on the same line, which in all practicallity is just an open end with a filter on it, won't the same thing happen?
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Old 04-25-2005, 11:19 PM
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There is a check valve in the PCV.
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Old 04-25-2005, 11:20 PM
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It is best to put the PCV line in its own port. However it isn't the same as an open line - the valve inside the PCV restricts flow based on pressure buildup in the crank case. It prevents unrestricted flow into the manifold.
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Old 04-26-2005, 12:38 AM
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So just to get things straight. One proper way of running this crank ventilation system would be a vacuum hose from the carb base (direct manifold vacuum) to the PCV into a gromet in one valve cover, then a breather in the other valve cover.

That simple, right?

Also, should I be worried if it seems that a lot of air is being pushed out of my valve cover? Someone told me it's a sign that my rings may not be sealing.
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Old 04-26-2005, 11:38 PM
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noone?
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Old 04-26-2005, 11:59 PM
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blow by

Oil coming out of the valve cover breather is caused by blowby. There is some amount of blowby in all engines. As the engine gets older there is an increase of blowby. There is also an increase of blowby at higher RPM. Just wipe off your valve covers occasionally so you don't get a buildup of oil on the motor.

Blowby can be an early indication of ring failure but blowby can also hit a certain point and not get worse for years.

My 88 Cavalier broke 5 rings. It was idling very poorly. There was so much oil coming up into the breather that the filter was floating in oil and it was leaving puddles on the ground. Oddly enough there was no sign of oil smoke in the exhaust.
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Old 04-27-2005, 12:00 AM
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belive it or not

i went by my friends shop because i suspected a vac leak (hes got a smoker) and i was right i got one in between the egr plate and the carb...anyway i for got to hook up the pvc line (where i pumped the smoke in) and when i got home i was leaking oil out of the rear main in a steady stream i figured after 300,000 miles its gonna have to come out now .after crawling around and throwing a micro temper tantrum ,i saw the line was off put it back on and now it drips but not like before B I O N i still don't

sr66
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Old 04-27-2005, 07:27 AM
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That's the purpose of the PCV valve system; it prevents stuff being blown out of holes in your engine all over the outside.
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Old 04-27-2005, 08:33 AM
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Thanks guys, I know that i need one now. I just want to get the set up for it straight since I don't have a schematic.

Quote:
So just to get things straight. One proper way of running this crank ventilation system would be a vacuum hose from the carb base (direct manifold vacuum) to the PCV into a gromet in one valve cover, then a breather in the other valve cover.

That simple, right?

Is this correct?
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