PCV/Crankcase breather

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I built a new-used engine for my plow truck.

oil for camshaft break in

Because I'm not able to use the original air cleaner from the new motor I don't have a factory provision for filtered air for the PCV.

I got slightly creative and found that I could get another PCV grommet and a chrome breather from Mr. Gasket fit right in.

But I'm wondering how well these breathers work and if anyone knows of anything better.



 
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Those breathers are not to let air IN, they are to let fumes (crankcase blow-by) OUT. The breather cap merely vents the fumes to the atmosphere and includes some packing to catch the oil mist. The other type allows the fumes to be drawn into the engine and burned. OEM arrangements used to include a "breather filter" to catch the oil. If you want to keep your personal pollution profile to a minimum you would want to use the second arrangement above. You can make it work with an appropriate pipe nipple on the underside of the air cleaner.

So, yes, the Mr. Gasket breathers "work" by venting the offending gases into the air.
 
It will function but how well it will function is anybody's guess, you'd have to measure it.

A better solution with the potential for better torque & horsepower, less knock and a cleaner intake tract is the exhaust extractor. See the link

https://forum.ih8mud.com/attachments/img_0826-jpg.953360/

img_0826-jpg.953360
 
Oh My Lord? Does anybody know anything here?!?

DBMASTER, you are only correct on engines with VERY worn piston rings.


The foam inside the chinese Mr Gasket will break down in a year or so.
Maybe two years. It's a poor design, anyway.

YES - as long as the ring seal is good and the PCV works like it should,
that filter will need to filter a LOT of air in it's life,
and the more poorly made they are, the more dirt gets into your oil.
 
Originally Posted By: Linctex
Oh My Lord? Does anybody know anything here?!?

DBMASTER, you are only correct on engines with VERY worn piston rings.


The foam inside the chinese Mr Gasket will break down in a year or so.
Maybe two years. It's a poor design, anyway.

YES - as long as the ring seal is good and the PCV works like it should,
that filter will need to filter a LOT of air in it's life,
and the more poorly made they are, the more dirt gets into your oil.


I stand corrected. I am more than willing to admit when I'm wrong and I appreciate the correct info so I don't make the same mistake again.
 
Originally Posted By: Linctex
Look for the ability to filter the air.

These look very well made:

Breather%20Filters%20and%20Don%20Ott%20Kinser%20Base%20Test%20048.JPG



something along these lines is what I was looking for, but I couldn't find anything with a 3/4" inlet that would fit the grommet.

the built in grommet like the one shown here is too big to fit the valve cover, as was all of the others I could find.
 
On any engine with a PCV valve, the breather in the other cover is going to be drawing air in.

Try a crankcase breather for a late 90s Chrysler 5.9. Those filter themselves and last a long time.
 
Originally Posted By: DBMaster
Those breathers are not to let air IN, they are to let fumes (crankcase blow-by) OUT. The breather cap merely vents the fumes to the atmosphere and includes some packing to catch the oil mist.

That's right - and to add, an open breather like that does not allow any fresh air to sweep through the crankcase and pull all the nasty fumes and moisture from combustion blow-by out of the engine. A closed PVC system does.

And yes, even engines in very good shape have some ring blow-by.
 
Yes, some, but if an engine and PCV system are in "very good shape," flow through the valve will exceed blowby rate much of the time. Therefore fresh air normally goes IN in the breather, making Linctex and DoubleWasp correct. Otherwise, there'd be little point in filtering, or calling the system "positive." Cruder crankcase venting systems (such as my '72 Subaru had) direct crankcase blowby to the intake instead venting to the atmosphere, but don't suck any fresh air into the system in any circumstance.
 
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I had to use the truck this weekend to do some fencing and shot a video of the old engine running. The amount of Crankcase vapor is absolutely astonishing.

But it does give a good visual on the amount of air that goes through the PCV system and how important the ability to filter the air going into the crankcase really is.

Check out at the end of the video where I hover the PCV valve above the grommet for a second or two. You can see the vapor getting sucked into the valve.

Now, why is there so much vapor? I'm not sure, but that is why it is getting a new engine. My guess is that it is the coolant evaporating out if the oil. Before the oil level started rising, I never had this kind of vapor coming out of the valve cover which leads me to think it is not blow-by. Blow-by, I think, would come out with much more velocity whereas this vapor seems to come out more as just steam rising.

83 k20 350 Crankcase vapor
 
^^^ Crankcase vapors are coming out of both valve covers due to the pressure inside the engine being slightly higher than the atmospheric pressure. Ring blow-by is the main thing that causes crankcase pressure. If it's also burning off coolant that leaked into the crankcase, then it makes it look even worse.
 
True. Even if there's not coolant leakage, remember normal blow-by gas is partially exhaust gas and thus contains a sizeable percentage of water vapor. When the engine is cold, some of that water condenses in the crankcase before the PCV system can suck it out.
 
There's a lot of water vapor inside of a healthy engine. If you want to be blown away by just how much, use a clear tube for your PCV hose temporarily. You'll see the water droplets and fogginess stack up. I say temporarily, because your vacuum will eventually suck a clear hose closed when combined with heat.
 
Originally Posted By: DoubleWasp
There's a lot of water vapor inside of a healthy engine. If you want to be blown away by just how much, use a clear tube ...
Long ago, I attempted to simulate what's now known as a catch can on my Subaru, which had no pcv system, just hoses venting blowby from the valve covers to the air cleaner housing. I used plastic bags spliced in between. The main result of that experiment was a lot of water condensing and accumulating in the bags in the winter.
 
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