Crankcase Pressure.

1. french_baguette Frequent Poster Joined: Mar 2010 Stoke on Trent Posts: 523 Mk1 VTS Nissan 350z

   #1 27th June 2010, 19:20

   Sorry this is the second thread i've made today but im a little concerned.
   
   The breather hose from the cylinderhead to airbox on my vts had split causing a vaccum leak, so as a tempory fix i've blanked off the hole on the airbox (using an old sparkplug and npt tape, pikey as!) and put some hose on the rocker cover end to a bodged together oil catch tank (vented to realease pressure ofcourse).
   
   Anyway. I have noticed then when the engine idles now and I remove the oil filler cap, there is alot of pressure in the rocker cover and oil spitting around...It certainly didn't do this before. Could this be because there is no longer a vaccum from the airbox to 'suck' the pressure out, so to speak? Because as it is now it's just being vented at atmospheric pressure.
   
   This isnt dangerous is it? The pressure is still going to be released at a fast enough rate to prevent the crankcase exploding?
2. user_35312 Established Member Joined: Jun 2009 Coventry CV6 Posts: 2477 Slowda Octavia vRS SOLD - Cam'd Chip'd VTR

   #2 27th June 2010, 19:38

   Quote:

   Originally Posted by french_baguette Sorry this is the second thread i've made today but im a little concerned. The breather hose from the cylinderhead to airbox on my vts had split causing a vaccum leak, so as a tempory fix i've blanked off the hole on the airbox (using an old sparkplug and npt tape, pikey as!) and put some hose on the rocker cover end to a bodged together oil catch tank (vented to realease pressure ofcourse). Anyway. I have noticed then when the engine idles now and I remove the oil filler cap, there is alot of pressure in the rocker cover and oil spitting around...It certainly didn't do this before. Could this be because there is no longer a vaccum from the airbox to 'suck' the pressure out, so to speak? Because as it is now it's just being vented at atmospheric pressure. This isnt dangerous is it? The pressure is still going to be released at a fast enough rate to prevent the crankcase exploding?

   Surely flowing to 'atmosphere' it will be releasing quicker?! I see what you mean though, my crank hose split.. i just taped up the return on the induction kit leaving it to puff oil in my engine bay. Trying going rusty now french piece of shit lol
3. french_baguette Frequent Poster Joined: Mar 2010 Stoke on Trent Posts: 523 Mk1 VTS Nissan 350z

   #3 27th June 2010, 19:47

   Quote:

   Originally Posted by Lew_C Surely flowing to 'atmosphere' it will be releasing quicker?! I see what you mean though, my crank hose split.. i just taped up the return on the induction kit leaving it to puff oil in my engine bay. Trying going rusty now french piece of shit lol

   
   Well in the induction there is a vaccum that is lower than atmosperic pressure which would suck the higher pressure out of the crankcase. I think?
   
   Good point about the instant waxoil though, however i dont fancy cleaning all the oil out my bay again, so think i'll leave it hooked up to the catch tank, or should I say coke bottle with holes drilled into the top!
4. user_35312 Established Member Joined: Jun 2009 Coventry CV6 Posts: 2477 Slowda Octavia vRS SOLD - Cam'd Chip'd VTR

   #4 27th June 2010, 20:00

   Quote:

   Originally Posted by french_baguette Well in the induction there is a vaccum that is lower than atmosperic pressure which would suck the higher pressure out of the crankcase. I think? Good point about the instant waxoil though, however i dont fancy cleaning all the oil out my bay again, so think i'll leave it hooked up to the catch tank, or should I say coke bottle with holes drilled into the top!

   I see what your saying though, I just haven't been around to doing anything about it.. ive drove with a split breather for 6 months but recently fully blanked the induction side of it and let the other side out the other way