blow-bye and breathers

grumpyvette

Administrator
Staff member
36firerat 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.
PROPERLY DESIGNED BAFFLED BREATHERS allow the engine too USE & LOSE FAR LESS OIL
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
PCV-Operations.jpg


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.

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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
piston_detonation_damage.jpg

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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Re: blow-bye, and breathers

LUVmachine said:
So finally get my first test drive in my LUV truck yesterday. After the drive I opened the hood and noticed the valve cover breathers dripping a small amount of oil and it happens to end up on the exhaust. Is there something that can be done to these old offenhauser type breathers to keep the oil in and let them keep breathing? I plan on eventually switching these valve covers out and using more of a updated style breather but for now this is what I have to work with. Overall for the first time out I'm happy with it. Not to mention it shreds the tires with zero effort.
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just a point of interest, breathers are designed to be located on the UPPER edge of the valve cover , NEVER the lower edge as shown ABOVE here
and and no your not alone in having the breather located in the wrong location,or alone having purchased valve covers with breathers having previously been mounted that way then sold, off as a result! all fluids tend to drain to the lower areas and oil in an engine tends to flow back and accumulate in the lower areas of the heads and valve covers, at higher rpms there can be a quart or more in the valve covers and lifter gallery areas
I see it frequently....with similar results as a result. YOU need to think it through and use the correct parts, place the breathers correctly and use well designed BAFFLED breathers and oil loss from a breather is MINIMAL, place it in the wrong area or use non-baffled breathers without a PVC valve forcing air to flow in through the breather and you have a near constant oil leak

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those breather tubes with the crossover lok really trick, but wont those get in the way of the filter assembly / water neck/ distributor, etc? i cant picture where on what motor you can mount those excapt on the back of a SBF with a tall intake manifold
 
So I want to replace the valve covers on my 85 and while there's a million valve covers to choose from on the various parts sites, very few of them seem to have a provision for an oil filler cap. I'm very confused by this, is there some way to get oil in a small block other than the third hole? I guessing there's some trick I don't know because I'm a youngin.

you do realize there ARE flip top valve covers that allow easy oil addition AND valve adjustments without them being removed from the engine right!
http://www.summitracing.com/search/bran ... =Ascending
http://www.proformparts.com/product-exe ... ory_id/249
topcoversb.png


pro-141-913_w.jpg

proform valve cover PART # 66704
Proform Video


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notice that a temporary oil deflection plate can be used in Ricks t-bucket using those removeable top valve covers to adjust the valves while the main component of the valve cover and gasket stays in place on the heads
cast pot metal valve covers, frequently have areas that are set up to be machined for a twist in oil fill cap and any decent machine shop can easily do that for a minimal price.
ID also point out that the better quality tall cast valve covers are structually stiffer or more rigid and tend to be more easily machined, less likely to leak if properly installed, and provide more valve train to rocker cover clearance, decent quality valve covers must be rigid and structually stiff enough to hold a consistent pressure on the sealing gasket and provide the required clearance to the valve train, the better quality cast or custom machined and fabricated aluminum valve covers have proven to be far better quality than the typical stamped sheet metal rocker covers
mtvalvecoverslargea.jpg


valvecovercap2.jpg

and aluminum valve covers, can be machined and welded to allow and oil filler cap to be used .
and remember you have the option of adding valve spring oil coolers if your going to extensively modify custom valve covers


valvecovercap3.jpg

Valve covers can also be outfitted with spring oilers, as shown on this small-block Chevy cover, to cool the springs during operation and help them live a little longer. That little hose fitting is connected to the pressure side of the oiling system from the outside of the cover and feeds oil into tubing that sprays oil on the valve springs.

there are thread ,in and/or screw in oil filler cap mounting kits,
that clamp with a retainer nut inside and flange outside,

these only require drilling the correct size hole in the correct location on a flat surface,
but be damn sure the clearances with the valve train are going to be correct before
you start drilling in the correct place, with the new oil fill caps install mounting components with the valve cover and valve train components installed and after carefully rotating the engine

907fill.jpg

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and weld in oil filler cap kits for valve covers
http://www.summitracing.com/parts/sda-070-2075/overview/
sda-070-2075_w.jpg

(one more in and endless list of reasons you really need a decent drill press,
g7946_det1.jpg

12" calipers
12cal.jpg

and a TIG welder)

CAREFULLY checking the valve cover, internal fit, to valve train clearance won,t hurt either
clay6.jpg

116_0701_04_z+valve_to_piston_clearnace+measure.jpg


on endurance applications like circle track or off shore race boats plumbing a separate pressurized spray bar to cool valve springs and rockers that feeds from either a passage in the block or a separate oil pump has proven to be very helpful in long term durability, because the rapid cycling torsional stress on valve springs can easily cause them to heat to over 700F if not bathed in a constant flow of oil that absorbs and carry's away the heat that builds up rapidly, most people don,t understand that almost 1/2 of an engines total heat comes from the valve train and bearing friction
Oilers966_Copy24.jpg

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THERE ARE VALVE COVER SPACERS THAT HAVE OIL SPRAY HOLES , and passages THAT DIRECT OIL TO THE VALVE SPRINGS
http://www.boocoo.com/auction/detail.as ... &id=313036
RELATED INFO
http://www.hardin-marine.com/p-12519-bb ... ystem.aspx


http://garage.grumpysperformance.co...fit-under-stock-valve-covers.6641/#post-21035

http://www.cpperformance.com/p-12518-bi ... ished.aspx

http://www.competitionproducts.com/Bill ... info/7500/


http://garage.grumpysperformance.com/index.php?threads/valve-cover-gaskets.190/#post-224

http://www.circletrack.com/techarticles ... index.html

http://www.popularmechanics.com/hom...ur-test-to-find-the-best-drill-press/?slide=1


http://garage.grumpysperformance.co...lve-cover-breather-hole-in-valve-covers.2005/
 
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