Anyone notice and wonder why there are two crankcase vents? One appears to be the typical one with pcv valve. The one near the front of the engine is large and enters before the throttle body. Is this unusual? If it is...

Thoughts and questions:
Could this be possibly some way the F20C engineers have taken to assure engine lube/cooling at high rpms? It has been stated that the engine burns oil with VTEC; could this possibly be the source on purpose? High engine rpms would also cause quite a vaccuum in that tube, possibly drawing in heavily oil misted air. Many have noticed oily intake and tb because of this vent tube.

If two vents are not unusual, then forget about the whole thing!

[Edited by Prolene on 02-24-2001 at 10:31 AM]

 

I think the second one you are referring to is in front of the TB which is a high pressure area. That would make it a fresh are input to the engine where the air pulled by the PCV is replaced.

 

Ah yes; I understand. The air gets "sucked out" by the PCV tubing leading to the lower pressure intake manifold so the relatively higher pressure area before the tb allows air to be replaced into the crankcase. Thanks!

 

CD is right on the money.......

 

Hmmm, this sounds like it makes sense but...
The positive crankcase pressure is caused by cylinder blowby, isn't it. The purpose of the PCV is to vent the increased blowby pressure. Why would another source be needed? Also, I don't think that the area in front of the TB would be high pressure except in a forced air or ram air application. What don't I understand?

Maybe to keep the crankcase "fresh and clean"

 

Pressure is a relative measurement. If the PCV is connected to the vacuum of the intake, one atmosphere on the fresh air side is high pressure.