Go Back  Offshoreonly.com > Technical > General Q & A
Valve Cover Breathers:  What Works? >

Valve Cover Breathers: What Works?

Notices

Valve Cover Breathers: What Works?

Old 05-01-2015, 09:26 AM
  #1  
Registered
Thread Starter
 
Join Date: Oct 2010
Location: Hemlock, MI
Posts: 922
Received 127 Likes on 74 Posts
Default Valve Cover Breathers: What Works?

Ok, currently I have the push in K&N breathers on my valve covers for my fresh 540. One on front of odd bank and one in back of even bank. After running last year I would get a little mist of oily mist from my rear even bank breather after pushing it hard. Not enough to signify issues but enough to make a bit of a mess in the bilge. I imagine this is a run of the mill issue after reading threads about it from searching but I couldn't come up with a definitive answer. My K&N breathers are un-baffled and there is no baffle under the valve covers except the stud girdles.

So here is the question: What do I replace my K&N breathers with, the nice looking tall bolt-on aluminum breathers or do I go to a catch can breather system? What has eliminated the issue for you guys as I have read the K&N breathers are notorious for this issue?
Gimme Fuel is offline  
Old 05-01-2015, 09:57 AM
  #2  
Registered
iTrader: (3)
 
Join Date: Oct 2007
Location: yorkville,il
Posts: 8,427
Received 87 Likes on 49 Posts
Default

when the oil gets to operating temp there is a steady mist of oil flying around under the valve cover,this mist finds it,s way out of a breather in the back of a valve cover.
mike tkach is offline  
Old 05-01-2015, 10:13 AM
  #3  
Registered
 
Join Date: Nov 2007
Location: IL
Posts: 161
Received 12 Likes on 3 Posts
Default

I got tired of fighting this and ultimately went with a catch can system last year.....no more mess.
rvander68 is offline  
Old 05-01-2015, 10:20 AM
  #4  
Registered
 
Join Date: Jan 2005
Location: Pasadena, MD
Posts: 3,570
Received 121 Likes on 39 Posts
Default

That's why I use PCV systems on my motors.
f_inscreenname is offline  
Old 05-01-2015, 10:22 AM
  #5  
Registered
 
Join Date: Feb 2012
Location: westville, NJ
Posts: 4,031
Likes: 0
Received 9 Likes on 7 Posts
Default

So there is no tube going from breather up to flame arrestor? Or pcv system? Before pcv cars used a metal tube venting crankcase down to the road. You must have some way to get crank vent back into intake air. You also get oil smell at low throttle-speed with your current setup.
dereknkathy is offline  
Old 05-01-2015, 10:29 AM
  #6  
Registered
Thread Starter
 
Join Date: Oct 2010
Location: Hemlock, MI
Posts: 922
Received 127 Likes on 74 Posts
Default

Originally Posted by dereknkathy
So there is no tube going from breather up to flame arrestor? Or pcv system? Before pcv cars used a metal tube venting crankcase down to the road. You must have some way to get crank vent back into intake air. You also get oil smell at low throttle-speed with your current setup.
No PCV or tubing going to flame arrestor. Smell of oil has not been an issue either. I run a custom multi port EFI system and I really don't want to run hoses to my arrestor or into my 2000 cfm throttle body or intake as I would like to go to a clear polycarbonate arrestor soon once it is dialed in. Currently running a 3"x10" SS Babron arrestor. I have tried very hard to keep the top of the motor clean from hoses and wiring.

Gimme Fuel is offline  
Old 05-01-2015, 10:34 AM
  #7  
Platinum Member
Platinum Member
 
phughes69's Avatar
 
Join Date: Dec 2001
Location: St. Clair Shores, MI
Posts: 2,040
Received 99 Likes on 53 Posts
Default

I was tired of the mess on the valve covers on my Corvette, so I installed a catch can system on each valve cover. A way to improve on the catch can could be to route the vapors off the catch can up yo the spark arrestor
phughes69 is offline  
Old 05-01-2015, 11:30 AM
  #8  
Registered
 
Join Date: Oct 2000
Location: Lakewood, NY, USA
Posts: 3,479
Received 315 Likes on 172 Posts
Default

How are the K&N installed? Eddie Young told me to mount the filter 6 inches above the valve cover. This allows the oil to settle out.

Padraig
Padraig is offline  
Old 05-01-2015, 11:54 AM
  #9  
Registered
iTrader: (2)
 
Join Date: Aug 2011
Location: bel air, md
Posts: 2,733
Likes: 0
Received 5 Likes on 5 Posts
Default

Originally Posted by Gimme Fuel
Ok, currently I have the push in K&N breathers on my valve covers for my fresh 540. One on front of odd bank and one in back of even bank. After running last year I would get a little mist of oily mist from my rear even bank breather after pushing it hard. Not enough to signify issues but enough to make a bit of a mess in the bilge. I imagine this is a run of the mill issue after reading threads about it from searching but I couldn't come up with a definitive answer. My K&N breathers are un-baffled and there is no baffle under the valve covers except the stud girdles.

So here is the question: What do I replace my K&N breathers with, the nice looking tall bolt-on aluminum breathers or do I go to a catch can breather system? What has eliminated the issue for you guys as I have read the K&N breathers are notorious for this issue?
I ran K&n breathers on my 632 never much below 6000 rpm and never had a drop of oil out the breathers. The breathers were both in the front of the valve covers (wouldn't clear exhaust in the rear).
Black Baja is offline  
Old 05-01-2015, 01:03 PM
  #10  
Registered
Thread Starter
 
Join Date: Oct 2010
Location: Hemlock, MI
Posts: 922
Received 127 Likes on 74 Posts
Default

Originally Posted by Black Baja
I ran K&n breathers on my 632 never much below 6000 rpm and never had a drop of oil out the breathers. The breathers were both in the front of the valve covers (wouldn't clear exhaust in the rear).
Yea, the only one that gets any mist out of it is the rear.
Gimme Fuel is offline  

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.