1978 for f100 302 ci has a vent on the valve cover with milky oil dripping out of it?

 

That would be a blown head gasket sir.

 

its rebuilt motor with new everything

 

The head gasket must have been put on wrong. Oil turns milky when water gets in the oil, usually from a blown head gasket, warped heads, or even a cracked block.

 

It's probably just condensation, what's the oil on the dipstick look like?

 

I had that happen..In my case, it was just condensation mixing with the oil vapors.

Unbolt the valve cover to verify. It's all milky then yes, something has gone awry.

I've got my fingers crossed for ya.

 

If you don't drive your truck a whole lot, and/or take it for short trips, the valve covers will be coated with milky, foamy oil. Any vehicle will do it, old or new. The fact that it's coming out the PCV vent isn't normal, though. PCV valve could be clogged up.

EDIT: too slow.

 

Good thing you jumped in! That sounds like a good question to ask hahaha.

 

Agree it is likely condensation. Crankcase vapor has moisture. If the oil in the sump was milky I'd be more worried.

Check PCV system and seal on the vent then take it for a good drive and warm it up. Also check for correct T stat as that will help keep engine temps where they need to be.

 

X2! Check the complete PCV system. Crap... Blue and White typed everything I was gonna say. I've seen this issue many times. This issue has fooled several people to think worse things were wrong as well.

 

x3 be sure and check the passage where the hose goes into the intake. Run a piece of wire through it, to make sure, it is not blocked by carbon.

 

Easiest way to tell if it's your head gasket. Take your radiator cap off and look at your fluid. If it's lower then where it oringially was then it's a head gasket. If it's the same probably just condinsation.