Valve Cover Breathers

njk53 · 07-29-2015, 03:18 PM

I have a theoretical case scenario I was wondering if I can get some comment on by the engine experts. If you have no valve cover breathers on either valve cover (V8 Engine of course), and are using just a PCV valve, can the crankcase pressure build high enough to cause the rear main seal to fail?

Eman · 07-31-2015, 09:25 AM

YES! A PCV system requires a breather to be a ventilation system. little or no vacum under full throttle which is when the engine is making the high amount of back pressure.

Lew Silverman · 07-31-2015, 11:53 PM

I found out by accident that you need a breather installed if you use a PCV valve system. I didn't lose a rear-main seal but I sucked a valve-cover gasket up pretty good!

07-29-2015, 03:18 PM	#1
njk53 Senior Member Join Date: Jul 2007 Location: East China, MI Posts: 504 Likes: 0 Liked 0 Times in 0 Posts	Valve Cover Breathers I have a theoretical case scenario I was wondering if I can get some comment on by the engine experts. If you have no valve cover breathers on either valve cover (V8 Engine of course), and are using just a PCV valve, can the crankcase pressure build high enough to cause the rear main seal to fail? __________________ Nelson Kowal Stock 345

07-31-2015, 09:25 AM	#2
Eman Member Join Date: May 2014 Location: E TN Posts: 472 Likes: 16 Liked 133 Times in 76 Posts	Re: Valve Cover Breathers YES! A PCV system requires a breather to be a ventilation system. little or no vacum under full throttle which is when the engine is making the high amount of back pressure.

07-31-2015, 11:53 PM	#3
Lew Silverman VIP Member Join Date: Mar 2010 Location: Newport News, VA Posts: 1,435 Likes: 371 Liked 129 Times in 59 Posts	Re: Valve Cover Breathers I found out by accident that you need a breather installed if you use a PCV valve system. I didn't lose a rear-main seal but I sucked a valve-cover gasket up pretty good! __________________ Lew Silverman #2070 "The Wagon Master" N/SA