PCV Valve Vacuum Leak
 

I bought a 1978 C20 292 I6 4-spd manual new in January, 1978, and I still use it.

Often, since new, when the motor is hot it shakes horribly at idle. The problem is that the PCV valve ball sometimes does not get sucked up tight which causes a vacuum leak and the shake. There is plenty of vacuum. Plugging the end of the PCV valve with my finger fixes the vacuum leak to demonstrate what is wrong. Removing the valve from the cover and turning it sideways drops the ball into place to make it work also, and it stays in place when reinserted into its hole. Replacing the PCV valve fixes nothing. Buying cheap or not so cheap ones also makes no difference. Besides being annoying, the shaking loosens the connection to the exhaust pipe which makes that joint leak.

There are probably millions of these cheap little valves in service, so they must actually work. Does anyone how I can fix this? Thanks.

Re: PCV Valve Vacuum Leak
 

GM had an issue with oil consumption on some of the 5.3s in trucks. The solution was a fixed orifice to replace the PCV. Not sure if 4.8 and 5.3 used the same valve number, but might be worth a shot.

Re: PCV Valve Vacuum Leak
 

plug the port on the carb, stick an aftermarket breather in the valve cover, every couple months wipe off the valve cover

Re: PCV Valve Vacuum Leak
 

Many different solutions. Here's mine. Use the PC valve thats in the valve cover as an elbow and put another inline.

Re: PCV Valve Vacuum Leak
 

I like the #4 answer. Do you have a recommendation on what to ask for at my FLAPS?

Thanks

Re: PCV Valve Vacuum Leak
 

First is a 70's Buick with a 231 V6. They have 2 hose barb ends but one is larger than the other. That might work for you.