PCV direction

[kreb]

i just wanted to make sure what way the PCV goes. it is inline from the tube on the manifold to the carb. there are arrows on the valve pointing to the manifold. the arrows should be in the position as if they were going into the manifold? it is opposite right now from when the motor builder put it back on.

benjamin

[DjD]

I recently purchased a PCV valve and the packaging said the arrow points to the carb, which is the direction of flow. Unfortunately, the valve didn't have an arrow on it so I was hoping someone would answer you. Can you tell me if the end that the arrow points to has the flat piece inside or the pin end?

[kreb]

maybe i got it wrong. i think the arrow went to the carb. if it is in the wrong direction what will happen?

benjamin

[Damage, Inc.]

PCV stands for Positive Crankcase Ventilation. It allows the pressure inside the crankcase to escape, instead of blowing all of your gaskets and seals out.

[Lippy]

Kreb:

I was about to post a topic this situation. My '88 GW was using about a quart of oil for every 250 miles this summer. I was doing primarily highway driving in hot temperatures. No oil leaks or blue smoke burning. On a hunch I checked the factory service manual and found that the PCV valve was in backwards. Basically at highway speeds the crankcase had a direct vent into the intake manifold. The engine was stucking it's own oil out and burning it. My PCV valve was in backwards. The arrows have got to go towards the firewall or manifold. Suck on the side that is the metal piece. It should flow then close with minor leakage. That side goes to the carburator.

Good luck

Lippy
'88 GW
Pure stock

[mtn goat]

Along those lines, just blow on one end...if your breath goes through that is the crankcase side. if its closed off, that is the carb side.

you could also suck...but that would suck

[DjD]

Lippy, I believe that is what the PCV is, gases flow from crankcase to intake, base of carb, so it's a closed ventilation system to re-burn the gases for lower emissions.

[porchpiggy]

But it's not just venting the crankcase gases, it's sucking them out with vac from the carb, hence POSITIVE crankcase ventilation. I know that sucking on it sucks, but I think that's a good test, but I would only do it with it not running. :D

[TexasJ10]

I can't help adding two cents here. You also need to make sure that the proper cap is on top of the oil fill tube. The proper cap has a fitting for a hose that connects to the air cleaner. Air is drawn into the crank case from this hose and exhaled though the PCV to the base of the carb. If there was no air being drawn in at the fill tube, I suspect the suction created at the PCV could draw oil rather than vapors. Does that sound right to everyone?

[DjD]

Very funny PP. I did suck on both sides of the PCV valve before installing it and both sides allowed some flow. So now I'm not sure what's going on.
Funny thing is, I hooked up a 3 foot hose to blow into the metal crankcase tube to make sure it wasn't blocked with crud, my neighbor saw me and offered me $10 to do his vehicle.

[tuckers89GW]

now wait a minute. I'm gonna have to look, but I believe my PCV valve has the metal end opposite the carb. that is how the previous one was installed on both of my Jeeps.

[Lindel]

Keep in mind, there are 2 different valves available, based on the age (or manifold) that your Jeep has. In the older Jeeps (I'm not sure what the cutoff is), the PCV valve sits in a grommet, directly on the manifold. In the newer FSJ's there's a pipe/hose that the metal portion slips into, and a plastic t-connection that goes to the carb, and the charcoal cannister. The older valves don't have this plastic piece. Any FSJ using the Edelbrock Performer manifold will use the older pcv valve, by default.