blow by or pcv valve?

[CarsonChris]

Bought a BII today. Talkin to the person that sold it to me. It loses power. Seemed ok during the test drive today. Did smoke out of the filler tube. Has oil leaking from the pcv valve and valve covers. Also looked like it might leak out of the dipstick. Is this pcv problems or blow by.

 

[RonD]

All piston engines have blow-by, it comes from the sudden increase in pressure when air/fuel is ignited, most of the pressure is used to power the crankshaft(power stroke) but some "blows-by" the rings into the crankcase.
As rings get worn the blow-by increases.

Pre-70's there was just a tube on the upper oil pan or block that pointed down at the ground, that allowed blow-by pressure to be let out of the crankcase, along with oil vapor.

Pollution concerns lead to the Pollution Control Valve(PCV), this recycled some of the blow-by/oil vapor back into the combustion chamber via the intake manifold.
But the PCV only pulls some of the blow-by pressure out.
There will also be a hose from the valve cover or oil filler tube to the air plenum(air cleaner tube to intake), this pulls out more blow-by pressure, the Vent hose.

Remove and clean out the PCV vacuum hose and the air plenum > valve cover hose, make sure they are not clogged with oil.
The PCV can get clogged with oil as well, it can be cleaned with carb cleaner, it is just an air valve, or replaced

If everything is clean and open then you probably have bad rings, this would, of course, reduce power in general, less pressure on the power stroke.
But could reduce power even more by the amount of blow-by/oil vapor entering the intake via the PCV and "Vent" hose.
You could try removing the Vent hose from the air plenum, plug that hole, and extend that hose down below the engine, so oil vapor won't end up all over the engine bay, or on the exhaust pipe, fire hazard.
See if engine performance improves, "ahhh" engine says, "more fresh air", lol.
This is an "air care" violation, so a temporary test

 

[94xlt4.0]

Pollution concerns lead to the Pollution Control Valve(PCV)

PCV is actually the abbreviation for "positive crankcase ventilation"
this is why its called a "pcv valve" not just a "pc" valve

 

[RonD]

PCV is actually the abbreviation for "positive crankcase ventilation"
this is why its called a "pcv valve" not just a "pc" valve

I like mine better

 

[adsm08]

I like mine better

But yours is wrong.

I know the PCV system is listed as emissions controls, but in reality it does very little to the tail pipe emissions since all that stuff just gets pumped out the tail pipe anyway.

It's primary purpose is to keep the oil from absorbing all that crap and keep the oil cleaner longer.

Frankly, since the whole thing can be rebuild for less than $20, except for the breather on the driver's side, if you have any suspicions at all about it I would just replace the valve and both hoses. Make sure you get braided hose. I made that mistake once. Unbraided hose collapses when the valve is closed and causes all sorts of fun issues until you figure out that you did something really stupid.