I have a 76 vette with a built up 350..... it was purchased the way it is (engine wise) anyway. when I have the pcv plugged into my valve cover, my covers leak and will even blow the pcv out of the grommet while driving. If I just pull it out and let it open to atmosphere, there seems to be no crankcase pressure coming out of the grommet and no leaking oil. Did the person hooking this up , hook it to an incorrect vaccuum port? Or do I maybe have a more serious problem? I can say this.... nothing else this guy did to the car was done right from crossed wires to badly mis-aligned belts. I think I have finally got it down to this one remaining problem and have been driving it with the pcv dangling under the hood and not plugged into the valve cover.

Thanks,

Loren.

btw: hi everyone, its been way too long since my last visit!!!!

 

Hmmm...is it in backwards? What is the other end of the tube connected to, and what is the other valve cover connected to??

 

the pcv is hooked to a pretty big line that goes to the front, center, bottom base port of my q-jet. The other valve cover only has the filler cap (non-vented).

another note, is that I may see a hint of blue smoke in the exhaust when it is plugged in as well. But clean as a whistle when breathing to atmosphere.

originally everytime I popped the hood the pcv was popped out, and only stayed in good when I wiped grommet and pcv down with laquer thinner to make for a non-oil lubed fit which made it stay in but of course started pressurizing my crank-case.

Thanks

 

Shouldn't the other valve cover have a crankcase breather hole? The PCV system needs air flowing through the engine to work. There's your problem...

 

In addition to the PCV, you have to have an air inlet into the crankcase. If you have a filler cap in the opposite valve cover, you will pressurize the carnkcase when you are at wide throttle openings, and the PCV will blow out. Install a breather in place of the oil fill cap.

The way the PCV system works is that the PCV pulls crankcase vapor (and pressure) when manifold vacuum is high (light throttle). It pulls fresh air IN through a breather, normally located in the opposite valve cover. On emission-controlled vehicles, this breather is a tube running from the valve cover to the air cleaner, and this allows the crankcase to pull filtered air into the crankcase and up through the PCV.

When the engine is under power, or at wide open thottle (WOT), there is no vacuum to pull air up through the PCV. Also at this throttle setting, there is some amount of ring blowby, even on a tight engine. Thus, the crankcase tends to get slightly pressurized. Under this condition, flow through the breather reverses, and crankcase vapors (and pressure) is relieved OUT of the breather. On an emissions car, the reason for the tube running to the air cleaner is so that these vapors will be ingested into the carb. On a non-emissions vehicle, you can use a simple vent breather and allow this to vent.

If you have no breather of any type, the crankcase pressure cannot relieve under power, and the PCV will get blown out of the valve cover.

 

 

Ahhhh, now I feel stupid. like alot of others, I have after market covers and air cleaner..... and obviously not set up right. In my own defense, it was like that when I got it though.

Thank you very much !!!



Loren