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| Pros & Cons of getting rid of PCV system.....; By just venting blow by gas into the air. | |
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| Tweet Topic Started: Nov 8 2014, 11:39 PM (3,674 Views) | |
| Rondawg | Nov 8 2014, 11:39 PM Post #1 |
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I was thinking of running a hose from the nipple on the valve cover down towards the bottom of the motor. Then use an old bolt and a clamp to plug up the hose that sucks the blow by gas into the intake. This way any blow by gas (oil vapors, moisture & any other crud) will not be sucked into the engine. That's how old cars were set up. I don't have to worry about emission checks here in NC. Good idea or not????
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| Robertfrank | Nov 9 2014, 03:55 AM Post #2 |
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Member
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I was thinking about this the other day. Maybe running a tube from the valve cover to either the oil pan or dipstick to let the oil flow back. I don't see it being an issue really. Just have to tap a hole in the pan, thread a nipple then run the tubing. |
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| Cobb | Nov 9 2014, 10:10 AM Post #3 |
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BANNED
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I got some blow by in the old insight. I was thinking about plugging the crank case breather tube on the air intake and install a second pcv valve on the valve cover crank case breather hose. This way the real pcv can pull a vacuum and help reduce oil consumption if I install the second pcv valve correctly and when I WOT the extra gasses just blow under the hood or down a segment of hose to the bottom of the engine compartment.
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| Rondawg | Nov 9 2014, 10:19 AM Post #4 |
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If you have raw oil coming out the PCV nipple on the valve cover you have problems. Its blow by fumes from what gets past the rings, oil vapors unburned gas fumes and probably water vapor too till the engine is warmed up. This whole set up is designed to try and reburn this mixture by sucking it back thru the intake. The sole reason for this whole system (as far as I know) is for emissions. My engine is freshly rebuilt and I just think by venting this gas into the atmosphere it would be good for the motor. Over time it would probably save a lot of crud from building up in the intake and maybe even keep the EGR system in good work in order too. |
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| Hanuman | Nov 9 2014, 02:29 PM Post #5 |
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"The Almighty Grounds Cleaner"
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mine is set up now to vent out as well......my only complaints #1 it stinks! at a stop light i have to put the heater on recirculate or it draws all that smell inside the car. #2 slowly a light oil film is coating large areas of the engine compartment...and road grime is sticking to it. |
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| perfesser | Nov 9 2014, 04:40 PM Post #6 |
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Elite Member - Former Metro owner
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You cannot vent crankcase pressure by running it from the crankcase to a different part of the crankcase. All you'll do is create a pressurized loop of hose. Back in the day we had hoses coming from the back of the valve cover to a point just below the engine. Anyone can see the discharge, including cops with an emissions enforcement fetish. And we had little problem with rust because of the oil slick covering the underside of the cars. Best idea - make it work like it was designed to. |
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| Rondawg | Nov 9 2014, 11:37 PM Post #7 |
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Perfessor....Why would you want to suck those fumes back thru the engine if you could avoid it? It really seems to me that over time those fumes could really be bad for the engine. Maybe over time this is a major factor in clogging up the EGR and causing valves to burn?? There is probably some sort of filter availablet that could be atached to the end of the vent hose. |
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| snowfish | Nov 10 2014, 02:36 PM Post #8 |
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Basic GearHead
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Positive ventilation is better for the engine. It will keep the oil cleaner, which we know, is better for the engine. The small amount, of contaminated vapor, is burned up instantaneously. Since it's being drawn out continuously, little by little, only benefits can be seen. EGR will not plug quicker because of the vapors. A plugged EGR does not burn valves. 100,000+ miles, at 3,000rpms, burns valves. 1991 & earlier do not have EGR. They burn valves the same. A Passive ventilation system, like you propose, lets the expanding vapors push themselves out. A thick cloud, of vapor, remains in the crankcase at shut down. This re-condenses and settles into the oil. Then it's pumped, back through the engine, to start the cycle all over again. I guess we have to decide which is better or worse. 1) Burning the vapor instantly and getting it out? 2) Letting the vapor re-condense and settle back into the oil? A Real vapor droplet separating catch can, like high performance race/drag cars use, will solve both concerns. A home made catch can will not do as good of a job. That's why Perfessor says to keep it stock and working properly. Just trying to keep things Positive.
Edited by snowfish, Nov 10 2014, 04:33 PM.
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| Greywolf | Nov 10 2014, 04:34 PM Post #9 |
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Mostly Harmless
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I used to think PCV was a dumb, TREEHUGGER, enviro-nut waste of plumbing and horsepower. As I came to know more over the years, I got smarter. Among the other things that can form in poorly vented crank-case gasses are sulphuric compounds that are highly acidic (IE: Bad for rings and bearings) that become distributed all throughout your oil system. Another problem is sludge formation. Some of the other products of crankcase gasses are chemicals that will combine with oil (especially old oil) that form tar and crud that in older engines is absolutely miserable to clean out. *They are similar to PLASTIC for a reason - petroleum is what most plastics are made from to begin with. *Diesel fuel added to the oil and then flushed soon after running long enough to loosen that stuff is one of the best ways But in my many years of tinkering the first clue I know of that someone has failed to make sure their PCV system is working right is that their whole engine is totally filled with GLOP - and may have a serious bad rod or main bearing knock. ~Not to mention worse blow-by than ever before, because the rings are stuck in their lands. So to my "ENLIGHTENED and SELF INTERESTED" way of thinking, the PRIMARY purpose of Positive Crank Case Ventilation is to keep engines clean and free of gunk that ruins them over time... PCV systems just plain make engines last a lot longer and work better. That they also help the environmental air quality? Pfffft... Good, fine, great. In racing usage, I tell ya what. I have a set of valve covers for a 351W out in the shop with big vent towers on them. The reason for that is that high compression race motors (especially if you just rebuilt them) have rings that may not even ever get the chance to fully seat. They raced last weekend - and they have to race again next weekend. What this means is that combined with that and way over stock compression, "SON! You gonna have lotsa blowby..." So what is normally done about it (OLD SCHOOL) is to put big vents on the valve covers, and set up a venturi in one of the exhaust headers to pull it out that way and burn it up. Where a PCV valve would be on the opposite valve cover there is a fitting that a tube is connected to down to the header. My Poppa used to have a 1961 Desoto too. It was designed with what is called a "ROAD DRAFT TUBE", and what that was is a cap on the back of one of the valve covers that had a long metal tube about 3/4 inches in diameter that ran straight down into the airstream underneath the car. The tip of that tube was cut at an angle so that air blowing past it from the front created a venturi effect that pulled crank case gasses straight out into the atmosphere. DOWNSIDE? It only worked if the car was moving forward at speed. DOWNSIDE 2: It also left a puddle in the parking lot, wherever it stopped moving The PCV method, on the other hand, uses direct intake manifold vacuum to PULL gasses out constantly, as long as the engine is running. Here is an excellent WIKI page on it that will not only verify what I have said so far - but provide you with an overview of all sides of it: http://en.wikipedia.org/wiki/Crankcase_ventilation_system Here is another article I found that talks about blowby gasses, and what is that stuff that gets into an engine... http://www.auto-rx.com/what-is-sludge-and-why-do-i-have-it-in-my-engine.shtml *NOTE: The second link is obviously from someone trying to sell something - and I am NOT promoting their product, I wanted to be sure and stipulate that. Edited by Greywolf, Nov 10 2014, 05:13 PM.
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| Cobb | Nov 10 2014, 11:09 PM Post #10 |
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Its my understanding that is one reason most throttle bodies are heated with engine coolant is to lessen the chance of it freezing or sticking with the venturi effect and vapors from the engine. Im not saying junk it, just rig it so the extra gasses can vent and not clog performance. These newer honda engines are pushing 11 to 1 compression and between VCM, valve seals, etc are producing a lot of blow by and Im sure that hampers performance. Ive had white smoke come from under the engine side of the hood twice near 6 grand before I shift. A lot of the old v blocks used a pipe that inserted and twisted into the valve covers and poked under the bottom of the car.
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| Rondawg | Nov 11 2014, 12:06 AM Post #11 |
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I just can't help but think that suckling them vapors up thru the intake is potentially bad for the intake. Surely with a factory set up those vapors are still gonna be in the crankcase after the engine is shut down.. And with modern synthetic oil, changed regularly, any contamination, sludge buildup etc. would be minimal compared to older cars. Surely not sucking up those blowby gasses would keep the intake cleaner.
Edited by Rondawg, Nov 11 2014, 12:10 AM.
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| perfesser | Nov 11 2014, 12:45 AM Post #12 |
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Elite Member - Former Metro owner
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Please reread the excellent post (#9) by Greywolf. You're basing your point of view on supposition and emotion. He posted data. If you can find something like he did to counter what he said, go for it, but when an engine is properly designed to perform a certain function, then performing that function is not going to hurt it. |
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| Mrbreeze | Nov 11 2014, 10:10 AM Post #13 |
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How can I put this, if you are having issues with blow by and or oil consumption you have bigger issues than a PVC valve scavenging vapors... |
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| Rondawg | Nov 11 2014, 10:24 AM Post #14 |
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Thanks for the input guys. It looks to me, like most any mod, you have tradeoffs. Keeping you intake cleaner, free from oily crankcase fumes could cause oil to get dirty quicker by running an open system. OR you keep it stock keeps the crankcase vented better, keeps you oil cleaner longer, less emissions,.....However certainly would, over time, build up carbon all around the intake. Maybe a set up like this photo is the best way to go? It keeps the stock system intact and also keeps at least some of the oil from getting back into the intake?? ![]() |
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| perfesser | Nov 11 2014, 10:29 AM Post #15 |
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Elite Member - Former Metro owner
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