Re: oil leak/oil dripping from carburator, MCM 140
KJSmitty said:
As I mentioned early on - a "valve", or for better clarification on my "regulating vacuum" comment - a device that restricts or regulates engine vacuum "loss", will be used if the PCV/CV system utilizes vacuum.
Whaaaaaa???? what the heck does all that even mean?????
KJSmitty said:
If not attached to a vacuum source, no valve. Maybe that's the elbow you are describing captJason - because if it is just an elbow attached to a manifold vacuum source it couldn't be more wrong! Why, because the minute you had a back-fire/pop through the manifold/carb/throttle body it would force fuel/flammable vapors directly into the crankcase - Other than that you would have an extremely large vacuum leak sucking oil from your valve cover not to mention ruining your drivability..
What the heck are you talking about there too??? do you mean automotive or marine in that statement?
In automotive, the pvc line is usually plumbed in somewhere after the air filter but before the throttle plate. the engine doesn't care if the hose is hooked up or not. It's not metered air. So it doesn't matter. and it's done that way, because the EPA nazi's says it has to be. End of story.
Now in marine, It doesn't HAVE to be that way. So for the most part it's not.
The crankcase only needs to be vented to atmosphere, and that's it.
It does not have to be hooked up to a vacuum source or anything else.
It is vented to the carb body to help cut down on oil odors.
KJSmitty said:
Why, because the minute you had a back-fire/pop through the manifold/carb/throttle body it would force fuel/flammable vapors directly into the crankcase - the exact reason for the valve/"P" in PCV etc.
Again I have no idea what your trying to say here. But......
The check valve in a PCV valve is a 1 way valve. Put enough pressure under it OR enough vacuum in front of it and the valve opens. (or some combination of the 2) The reason why it is called a POSITIVE crankcase vent valve is because crankcases make POSITIVE pressure.... always.
Has nothing to do with the actual piece of plastic itself.
Think if it this way. If an engine is off (doesn't matter if its a weedwacker here, as long as where talking 4 stroke)
There is 14.6 psi of air in every part of that engine. There's 14.6psi in the intake and exhaust manifolds, there's 14.6psi in all the cylinders, and there's 14.6 psi in the crankcase.
When the engine runs. Air pressure goes down in the intake manifold. And we measure the phenomenon of high pressure rushing in to fill the low pressure event as "vacuum". There's still air pressure in there, but it is less than 14.6psi. Its often said that its negative pressure or vacuum, but that is not the case. There is pressure, just less than 14.6psi.
Now on to the crankcase. when the engine sits, we already said there is 14.6psi in it.
Now when the engine runs, there is still going to be 14.6psi PLUS whatever is added to that by blowby. you may have .5 psi of total blowby every stroke, so that would make your crankcase pressure 15.1psi. Since Hi goes to low, the POSITIVE crankcase pressure escapes under its own power to the LOWER pressure atmosphere because the pressure in the crankcase WANTS to equilize.
Valve or no valve it doesn't matter. There only NEEDS to be a hole.
Whatever else is in that hole is because some epa nazi or some whiney customer who doesn't like the smell of oil complained enough.
I think your overthinking this.
Jason.
