While straightening out some issues on the 351W in my '90 I discovered that the PO had completely removed the PCV from the valve cover, just leaving the hole in the valve cover open. Other than the obvious issue of foreign material possibly getting into the engine, what would potential side affects of this be?

I will be installing a new PCV now that I've got the necessary grommet, and T40 socket to remove the upper intake runner.

 

Only problem I can think of is your oil getting contaminated. Might want to change it.

 

Oh yeah. The truck will have a complete fluid change as I work through things.

 

Nothing, as long as he capped off the vacuum line.

Although crud will get in there.

 

The vacuum line was connected to some goofy after market thingy. I removed it and am restoring the PCV back they way it should be. Glad to know it shouldn't have caused any issues other than the potential for foreign matter getting in through the open hole.

 

Pressure inside block can rise during high RPM or hard pulling and cause oil leaks from front and rear seal. Left unregulated the engine blowby will cause sludge to form and the acids will attack engine parts.

 

But in the case of no PCV, just an empty hole in the valve cover, pressure can't rise, so it shouldn't be an issue.

This makes sense and I can see it as potentially being a problem. I'll be pulling the valve covers to replace the gaskets. It will be interesting to see what I find. I know it's only one area, I'd think it will give some indication.