blacknight
Superman, uh mod
Copied and pasted from another site
The crankcase, that which contains the crankshaft and connecting rods, is the bottom side of the engine - you can see the bottom of the pistons from under there. Compressed fuel and air mixture burns in the cylinder on the top of the pistons. When the rings become tired and worn they allow some of this compressed and burning mixture to leak past and escape into the crankcase. That is called "blow by".
In old engines that blowby simply vented into the atmosphere via a tube called a crankcase vent tube. The EPA found bad stuff in that blowby gas and mandated that the engines must suck up that stuff and burn it to render it harmful in some other way. In came the PCV which stands for Positive Crankcase Ventilation, named after the then head of the EPA Pierre Positive.
This system makes the engine suck the junk out of the crankcase via the PCV Valve into the intake manifold and back thorough the system. Welll, if that system is sucking the junk out, there must be a source of air to go into the crankcase else you would just implode the engine and the oil pan would collapse. Soooo, they ran a tube from the top of the valve covers to a source of clean air so that dirt would not get sucked into the crankcase. (note: the valve cover covers the valve train but that is also part of the crankcase - air and blow-by move readily between those zones in the engine.) The source of clean air which was chosen is the air cleaner - makes sense, except for the fact that the air doesn't go thorough the air cleaner filter, so they put a little kotex-like pad in there to clean the bugs and stones out of the air.
Remember now, the air is supposed to flow from the air cleaner's Kotex pad thorough that hose and into the valve cover, circulate around the crankcase and get sucked out via the PCV Valve. When the blow-by becomes so excessive that the PCV Valve system can't remove it, it has to go somewhere! Else the crankcase pressure would become excessive and the engine would explode. The place that it goes is back thorough the hose to the air cleaner - THE WRONG WAY!!! Of course it carries any oil in the valve cover back with it and that's what you mop up two or three times a month or week if it's really bad. Bottom line?? It's time for a new box of kotex or an engine overhaul, whichever is cheaper. (there is one other solution - see below)
If you do find oil in your air cleaner it may well be that your PCV valve is stuck closed and is therefore not sucking the blow-by out of the crankcase but rather, it is blowing back into the air cleaner. Make sure to check the PCV Valve before overhauling your engine!!
The crankcase, that which contains the crankshaft and connecting rods, is the bottom side of the engine - you can see the bottom of the pistons from under there. Compressed fuel and air mixture burns in the cylinder on the top of the pistons. When the rings become tired and worn they allow some of this compressed and burning mixture to leak past and escape into the crankcase. That is called "blow by".
In old engines that blowby simply vented into the atmosphere via a tube called a crankcase vent tube. The EPA found bad stuff in that blowby gas and mandated that the engines must suck up that stuff and burn it to render it harmful in some other way. In came the PCV which stands for Positive Crankcase Ventilation, named after the then head of the EPA Pierre Positive.
This system makes the engine suck the junk out of the crankcase via the PCV Valve into the intake manifold and back thorough the system. Welll, if that system is sucking the junk out, there must be a source of air to go into the crankcase else you would just implode the engine and the oil pan would collapse. Soooo, they ran a tube from the top of the valve covers to a source of clean air so that dirt would not get sucked into the crankcase. (note: the valve cover covers the valve train but that is also part of the crankcase - air and blow-by move readily between those zones in the engine.) The source of clean air which was chosen is the air cleaner - makes sense, except for the fact that the air doesn't go thorough the air cleaner filter, so they put a little kotex-like pad in there to clean the bugs and stones out of the air.
Remember now, the air is supposed to flow from the air cleaner's Kotex pad thorough that hose and into the valve cover, circulate around the crankcase and get sucked out via the PCV Valve. When the blow-by becomes so excessive that the PCV Valve system can't remove it, it has to go somewhere! Else the crankcase pressure would become excessive and the engine would explode. The place that it goes is back thorough the hose to the air cleaner - THE WRONG WAY!!! Of course it carries any oil in the valve cover back with it and that's what you mop up two or three times a month or week if it's really bad. Bottom line?? It's time for a new box of kotex or an engine overhaul, whichever is cheaper. (there is one other solution - see below)
If you do find oil in your air cleaner it may well be that your PCV valve is stuck closed and is therefore not sucking the blow-by out of the crankcase but rather, it is blowing back into the air cleaner. Make sure to check the PCV Valve before overhauling your engine!!
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