Proper crankcase ventilation setup

[biomedtechguy]

It could be wear, worn rings, etc in my motor. I have a nice cylinder pressure testing tool, I just haven't used it.
I have to point out for clarity that in my case I did NOT have a blowby problem until I changed from the stock PCV valve to "one that fit" my new valve covers which are baffled IOW a plate blocking liquid oil where the holes are in the top of the covers. So I blame the "random" PCV valve.
Once I read the articles and M/E Wagner's website and watched their videos, I was sold on how important the PCV valve is, and that is why I bought theirs and I will buy their Pontiac version for my wife's 421 Tri-Power GTO. Her motor is a fresh rebuild with no obvious PCV valve issues, but M/E Wagner's tunable one is so awesome I want one for her car too.

 

[Ranger16]

An engine does not need a vacuum source on the vent in order to vent.

True, but it DOES need vacuum to POSITIVELY vent and keep a fresh air flow.

 

[vintage chromoly]

Explain why a crankcase needs "fresh" air.

The end game for crankcase ventilation is to remove the pressure introduced by blowby.

Whether you introduce that pressure directly into the atmosphere or draw it into the intake to be reburned, is a matter of emissions.

 

[Ranger16]

It's not only the pressure. If you don't have "positive" crankcase ventilation, all the blowby gasses stay in the crankcase (without the pressure). That along with condensation is what creates sludge.

https://en.wikipedia.org/wiki/Crankcase_ventilation_system
"A crankcase ventilation system (CVS) is a one way passage for the blow-by gases to escape in a controlled manner from the crankcase of an internal combustion engine.

The blow-by gases are generated when a small but continual amount of gases (air, unburned fuel, combustion gases) leak from the combustion chamber past the piston rings, that is, blow by them, and the piston ring gaps to end up inside the crankcase, causing pressure to build up in there. Additional sources of blow-by that contribute to this effect are gases leaking past the turbocharger shaft, the air compressors (if present) and in some cases the valve stem seals. The blow-by gases, if not ventilated, can condense and combine with the oil vapor present in the crankcase forming sludge or cause the oil to become diluted with unburned fuel, degrading its quality and decreasing its effective life."

 

[vintage chromoly]

Blowby gases evacuate the crankcase because the atmospheric pressure is lower than the crankcase pressure. The crankcase is "positive" in relation to the atmosphere.

An additional vacuum is not needed to evacuate the crankcase. The main purpose of a PCV evacuation system as opposed to a draft tube or open element breather, is so the gases get reburned for better emissions.

 

[Ranger16]

I would agree with both of your statements in theory and to a point, but I think POSITIVE ventilation will create a much better air flow through the crankcase and evacuate much more of the sludge causing gases. Personally, I would not run without it.

 

[biomedtechguy]

From M/E Wagner's website:
We spent many sleepless nights trying to figure out why the rear main seal was leaking when it was carefully installed, how three different carburetors could respond incorrectly on the same engine, and why we smelled oil while driving.

Our quest led us to the importance of the PCV system and its function. Like many we believed that if an engine has open valve cover breathers, the crankcase would be ventilated properly. We learned that is not true.

A poorly ventilated crankcase results in a build-up of pressure and moisture along with the creation of acids and sludge. The PCV system if incorrect has the ability to affect all aspects of engine running and performance.

When working with a modified engine, the stock or aftermarket replacement PCV valve is often incorrect in flow and transient response. This mismatch frequently results in a wide range of tuning problems. It also allows vapors, moisture and pressure to build in the oil pan.

A modified engine has a different vacuum profile and cylinder fill signature along with a unique amount of blow-by past the piston rings. The replacement valves are not faulty; they are made for a stock engine and not even a mildly modified one.

I bolded some areas for emphasis.
You all can do what you like. I'm sold, and I don't have to wipe oil off my valve cover any more.
Whenever I can make the time to tune my M/E Wagner PCV valve I will follow up.

 

[dvw]

Explain why a crankcase needs "fresh" air.

To be honest it doesnt. Using a vacuum pump the crankcase pressure can be drawn below atmospheric. This will make more power and help ring seal. Not really a street deal though.
Doug

 

[vintage chromoly]

I pull 7 inches of vacuum with a dry sumo on my boat engine.
I also have a pop off valve on one valvecover to relieve pressure should the crankcase ever become positive.
I use a Peterson vacuum regulator.

My system vents through a catch can / breather on my oil tank.

To be honest it doesnt. Using a vacuum pump the crankcase pressure can be drawn below atmospheric. This will make more power and help ring seal. Not really a street deal though.
Doug

 

[vintage chromoly]

You can see the vacuum relief valve in this pic:

 

[vintage chromoly]

Also, I'm of the belief that getting your oil up to proper temp is way more critical to keeping moisture and "sludge" out of the oil than having a PCV valve.

All this said, I do use a PCV valve on my coronet. I'm only saying that it isn't the only way to relieve pressure in the crankcase.

 

[Triple Black 73]

M/E Wagner Performance PCV Valve on its way.

It never fails! I have an issue: no PVC on new MP valve covers. Looks in the forum for a solution, "oh wow look at this thing, that's awesome!! but OMG!! It's $130 bucks! ...but it's soooo pretty! must have..."

 

[oldbee]

To be honest it doesnt. Using a vacuum pump the crankcase pressure can be drawn below atmospheric. This will make more power and help ring seal. Not really a street deal though.
Doug

Gotta go with Doug, just like the crankcase evacuation systems used on race cars since the late 70’s. It’s also emissions, but it drops the crankcase pressure buildup also which is a good thing overall even on the street.

 

[Ranger16]

Also, I'm of the belief that getting your oil up to proper temp is way more critical to keeping moisture and "sludge" out of the oil than having a PCV valve.

I would certainly agree that oil temp is extremely important in burning off the moisture that creates sludge. Which is more important is debatable. I'd be hard pressed to pick one over the other. I'd give both equal importance.

 

[AR67GTX]

I've read glowing reports from the Ford and Chevy engine guys about the Wagner PCV (valve) also. Seems to be an excellent product. Seems I remember a lot of complaints about supposedly correct reproduction or replacement PCVs that didn't function adequately.

 

[not so famous bob]

I've read glowing reports from the Ford and Chevy engine guys about the Wagner PCV (valve) also. Seems to be an excellent product. Seems I remember a lot of complaints about supposedly correct reproduction or replacement PCVs that didn't function adequately.

on my 505" wedge, I used a left over pcv valve from trying diff. things on a 600 horse sbc I built. With the pcv hooked up and a breather on the other side (like a 68 street hemi came out with) , my rear main doesn`t leak, with two breathers , one on each valve cover , it did leak !!-----------NUFF SAID !

 

[Wietse]

I rather believe the name should be "Forced" crankcase ventilation instead of Positive.
Yes, the design was originally made to reduce emission but after testing and designing they found a lot more benefits with this system.
It was not designed, in any way, to prevent over pressurization of the crankcase caused by blow-by. (a simple breather alone can do that)
The amount of air drawn through prevents the oil sludge and condensation, including creating a slight under pressure in the sump to help shaft seals keeping the oil inside.

I'll give mine some time and see if there is any issues arising in the near future with my "basic" PCV.
If I had to change I would also go for M/E Wagner PCV, pay some and you get some.

 

[MW 413]

I would agree with both of your statements in theory and to a point, but I think POSITIVE ventilation will create a much better air flow through the crankcase and evacuate much more of the sludge causing gases. Personally, I would not run without it.

Absolutely correct. I worked on many engines in the day when they still had open crankcase vents and no PCV system and when you pulled the oil fill cap or valve covers they were full of sludge (Yellow-brown milky color). PCV was one of the biggest improvements to engine longevity. There are no down sides to running a PCV system.

 

[biomedtechguy]

I would also go for M/E Wagner PCV, pay some and you get some.

Yes! It is an exceptional product. Given the benefits offered in a tunable PCV valve and what it has done so far for me, $139 is cheap compared to what my car and its components cost. Well worth the money!

 

[not so famous bob]

Yes! It is an exceptional product. Given the benefits offered in a tunable PCV valve and what it has done so far for me, $139 is cheap compared to what my car and its components cost. Well worth the money!

The one I used cost less than $4 when I bought it, no way in hell I`d pay $135 for one ! My cam wont produce that much vacuum anyway.