PROPERLY DESIGNED BAFFLED BREATHERS allow the engine too USE & LOSE FAR LESS OIL36firerat said:I have stock 305 that builds crankcase pressure. I started with a breather on each valve cover, had issues with pressure, switched to a pcv still have issues. The issue is inconsistent though, one day a short drive will push oil, the next time it might be all day before I have an issue. I might go 3-4 days and no issue.
http://mewagner.com/?page_id=1221
If you have oil mist or drips of oil exiting the breathers theres potentially several reasons the cause is likely to be a badly designed non baffled breather or a defective PVC valve that's not allowing air flow to be sucked IN thru the breather, , rather than crank case pressure allowing oil mist to exit the breather
(1) the engines rings are not sealing correctly resulting in higher than ideal crank case pressures.
http://garage.grumpysperformance.com/index.php?threads/maximizing-piston-to-bore-ring-seal.3897/
http://garage.grumpysperformance.co...g-and-installing-connecting-rods-pistons.247/
http://garage.grumpysperformance.com/index.php?threads/piston-to-bore-clearance.4630/
http://garage.grumpysperformance.com/index.php?threads/installing-rings-in-piston-grooves.9490/
(2) defective PVC valve
http://garage.grumpysperformance.co...lve-cover-breather-hole-in-valve-covers.2005/
http://forum.grumpysperformance.com/viewtopic.php?f=87&t=4636&p=12451#p12451
without proper venting an engines internal pressure builds , due to cylinder pressure leaking past the rings,and eventually will cause oil seals or gaskets to leak oil.
READ THE LINK
http://garage.grumpysperformance.co...stalling-the-intake-manifold-distributor.464/
(3) improper breather design or improper location on the valve cover
http://www.jegs.com/i/JEGS-Performance-Products/555/52205/10002/-1?parentProductId=763433
In a properly functioning engine the PVC valve allows engine vacuum to draw fresh outside air into the engine as it operates through the breather,
pressure in the crank case, you see as blow-bye out the breathers on valve covers is the result of cylinder combustion pressure, or to a far lower degree compression, getting past the ring to bore wall seal,the obvious best answer to reducing it is better ring seal.
now doing a ring and bearing refresh/and rebuild is just a weekend deal if your set up with the tools and have a place to work, but of course you may need a re-bore and new pistons, if the bores worn. and if thats true it will take longer and get more expensive due to the labor and machine shop costs and parts required, intermittent blow by is frequently the result of minimal ring damage due to detonation
most installed engines are slightly tilted towards the rear to help oil flow return, to the sump, in the crank case thus the forward 1/3rd of the upper inside roof of the valve covers tends to be a better place to locate breathers and PVC valves to limit oil loss, on most V 8 engines.
if the edges of the piston lands look rounded off slightly and FROSTED that's the results of detonation, the rough stuff it micro sized bits of molten piston aluminum , that got transferred to the combustion chamber and exhaust port surfaces. do a leak down test,and try it at both TDC and BDC on each cylinder, it will help point to the cause
you can cure the problem at its source
[1] synthetic oil desolves that yellow 3m weatherstrip gasket adhesive than many guys use over a few months time so you cant use it to glue valve cover gaskets
[2]you must use a o2 safe gasket cement like the BLACK RTV silicone cement and you must clean and degrease the cover with acetone or a similar solvent before glueing on the gasket to get the best retention
[3]you need to allow at least a few hours to over night, depends mostly on temp. for that black silicone gasket cement to set up before installing the valve covers, and placing them gasket side down on a table with a sheet of wax paper under them and a 20lb weight on top of each valve cover while the cement sets up is the best way to insure the gaskets stay correctly aligned on the valve covers perimeter
[4]a light coat of (PAM) cooking spray on the lower gasket surface keeps them from sticking to the cylinder heads after installation
[5] these gasket retaining rings add a great deal to the valve covers ability to firmly hold the gasket WITHOUT bending SHEET METAL VALVE COVERS OR CRACKING CAST ALUMINUM VALVE COVERS AND ARE WELL WORTH THE MINIMAL COST
[6]doing it correctly the first time saves time and money
or you can deal with the results
http://www.jegs.com/i/JEGS-Performance-Products/555/52205/10002/-1?parentProductId=763433
viewtopic.php?f=52&t=2005&p=35478&hilit=breathers#p35478
viewtopic.php?f=87&t=4636&p=35467&hilit=crank+case#p35467
viewtopic.php?f=54&t=2207&p=12639&hilit=crank+case#p12639
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