breather filters ?

[craig85]

first of i apologise if theres already a thread somewhere , but i gotta shoot back work , the pipe that comes out of the rocker cover and goes back into the airbox , is that a good or bad thing ? is it hot dirty air going back in the airbox and is that what a breather filter replaces and sorts out ? cheers to anyone who can help and again sorry if a thread already explains this

[RustyM]

Its the oil breather just recirculates oil back into the engine, not sure on the purpose of this. Personally i dont like oil breathers that replace this pipe as they tend to drip oil everywhere and i also believe it wont pass an m.o.t with one fitted. I would say keep the pipe in place tbf

[RustyM]

After a bit of googling i have discovered that the breather is there to release a build up in pressure.

"I assume you are talking about piston engines here. The movement of the pistons and the clearance between the piston rings and the cylinders allows some of the presure created by the explosions in the cylinders to pass into the crankcase. If the crankcase was a sealed chamber then the seals around the crankshaft would blow out dumping the engine's life blood, oil, over the side. This would result in a large silecence from the engine. The breather is the vent to release this pressure. This keeps everybody happy"

Hope this helps

[craig85]

cheers , yea big help mate

[RustyM]

Now i have a question, which is better for performance? Does anyone know? Would cleaner air straight from the filter presumably not be better for combustion therefore creating more power or does the oily air help in some way?

[pepsimax]

Got a breather on my vtr engine, it was a little 15mm cone thing...

Never leaked any oil... but does make the engine bay noisier as you can hear the tappets with filter in place. I only put one on as I have other filters matching on the throttle bodies...