i have a 1979 f1504x4 with a 351m. im new to working on the motor, (just finshed the susupension) and when my motor is running i am getting smoke coming out of the passenger side valve cover hole. ( the hole on the back of the cover, i think its for the pcv valve??) does that mean i need a overhaul, or is there something major wrong???? i just didnt want to spend anything on the motor if i could find a decent used one cheap if there is something majorly wrong. thanks

 

I'm betting that it is just vapor, but couldn't say for sure without seeing it in person. Are you missing a pcv? PCV's are usually on the drivers side valve cover and a breather is usually on the passenger side valve cover.

 

That is the hole for the pcv valve. It is intended to recirculate those vapors beck into the combution chambers. Put in a pcv valve and it should be connected to a hose which goes to the air cleaner.

 

yeah because the one on the drivers side (the oil fill cap) i believe it goes and ties into the carb, but dont quote me on it. ill get a pcv and run it to the air filter. but what about the smoke, maybe from some wore out pistons&rings???

 

Tastyklair and I both tend to think that it is just vapor. If everything is hooked up, you wouldn't see it. If the piston rings were shot, then you would have blue smoke puffing out of your exhaust.

 

ALL engines have blowby, the piston rings do not seal perfectly. Hook up the PCV system with a NEW PCV valve.

 

The PCV valve goes to the intake manifold. The one from the air cleaner should go to the other side. That is air into the crankcase, the PCV valve is the air out.

 

Back in the days of environmental abandon, engines vented any crankcase gases and blow-by materials through a tube right out onto the ground called a road draft tube. No valves were required. As time and engineering improvements marched on, a simple system was devised to ventilate the engine and re-burn these gases and materials back through the engine for cleaner air AND A CLEANER ENGINE. At the heart of this system is the PCV valve. PCV is an acronym for Positive Crankcase Ventilation. A PCV valve is only half of a two-part system. At one end of the system is a breather, which allows fresh air into the crankcase. At the other end of the system is the PCV valve itself, which meters spent gases and combustion by-products back through the engine relative to engine demand. The breather can be a cap with a filter on the valvecover, or a hose from the cover to inside the air cleaner housing where it might have a filter of it's own or a vent inside the engine air filter.

At idle the engine isn't working very hard and the valve remains mostly closed, drawing a small amount of fresh air into the engine and metering the crankcase gases back into the engine. At full throttle the engine works harder and creates more crankcase gases, so the PCV valve opens wide to let more through. If the valve or lines get gummed up with gunk or the control spring or valve wears out it won't meter properly.

When to Replace:

If the PCV valve is stuck open at engine idle, too great a quantity of spent gases are let through. Rough engine idling and stalling can be the result. If the PCV is stuck closed, pressure inside the crankcase can build up and the gases can force engine oil up through the breather and air filter causing excessive oil consumption and a fouled intake system. The good news is that replacing the PCV valve is both easy and inexpensive.

Since most PCV valves open and close by way of a spring and plunger, they should be checked or replaced annually or every 20,000 miles which ever comes first, or according to your vehicle's service schedule. Just because the valve rattles does NOT mean it is good. Compare the valve plunger position with a new valve which will show a collapsed spring. Since a crucial part of proper PCV system operation is a positive seal, it's also a good idea to check all hoses, grommets and clamps when servicing the valve. Always replace cracked and leaking rubber and defective clamps when replacing the PCV valve.