3.0l PCV valve, "rattles"?

[ptf18]

Are the 3.0l PCV valves LIGHTLY spring loaded in the closed position?

OR can you see the internal check valve "rattle" about inside the valve body?

 

[RonD]

No spring just a weighted valve inside, yes, you should feel/hear the weighted valve move if you shake it, doesn't mean its "good" just that valve is not stuck

PCV Valve is there to pull out "blow-by" from crankcase/valve cover areas
Blow-by happens in all piston engines when a cylinder fires
When a cylinder fire pressure inside exceeds 1,000psi which pushes the piston down and adds power to the crank shaft
When this happens some of this pressure will "blow-by" the piston and rings and into crank case area, and this blow-by is "exhaust" gases so pollution
As a side note the exhaust gases are at close to 1,500degF at this time, so VAPORIZE some of the oil on cylinder walls and piston and rings as it passes by, ALL oil vapor inside an engine comes from this, no other place in an engine gets hot enough to vaporize oil

In the old days there was just a vent in upper oil pan or lower block that vented this exhaust to outside air, and its oil vapor
PCV system was added to eliminate this pollution

PCV valve is hooked directly to intake manifold vacuum, so 18-21" of vacuum at idle when Blow-by is low, low RPMs
This high vacuum sucks UP the weighted valve, doesn't close it just less suction
When you accelerate vacuum drops and blow-by increases, so weight valve drops and suction increases to pull out more blow-by gases
Pretty simple setup
The blow-by gases are sucked into the intake and re-burned with new air/fuel mix

The oil vapor can be an issue, it can clog up a PCV valve and its hoses
Using a good grade of oil lowers vapor, but it can't be eliminated
Cleaning or replacing PCV Valve every 3 oil changes is good to do or every 2 oil changes when engine gets above 200k miles
Blow-by increases with miles on engine because rings don't seal as well, so will oil vapor

 

[alwaysFlOoReD]

Wow, never knew how often the pcv should be changed....

 

[RonD]

Most never change them, lol
The Beather hose just sucks in the blow-by and oil vapor so throttle body gets a nice coating of oil, you know, to keep it lubed