Is PCV Valve the stupidest thing?

Status
Not open for further replies.
Joined
Jan 18, 2013
Messages
751
Location
usa
The positive crankcase ventilation or PCV valve.

Quote:
All automotive engines are lubricated with oil and when oil is churned by moving parts, pressure is produced. Piston rings and valve guides also leak slightly producing pressure in the crankcase. Many years ago, they simply vented the pressure into the atmosphere with a road-draft tube and breather cap. Today we use a positive crankcase ventilation or PCV system to handle this and other task.

How the PCV system works

The PCV system is relatively simple. An inlet hose connects to a filtered air source. This is used to supply clean air that is drawn though of the engine. Most of the time this air is supplied through the engine air filter. On a few designs there is a separate inlet filter that cleans the incoming air for the PCV system only. This filtered air flows through the engine, picking up fumes and vapors. The air exits through another hose, connected to manifold vacuum. The flow of air draws fumes from the crankcase and burns them harmlessly in the engine. This also creates a slight vacuum, relieving any pressure that may build. Negative pressure helps to prevent oil leaks and oil consumption by the engine. The PCV valve also helps regulate the amount of air flow, which helps prevent oil being drawn out of the engine.


Quote:
It is also one possible cause of expensive oil leaks and sludge buildup in an engine.


For me and my 2000 Dodge Neon, it's the only thing that makes me repeatedly top off my motor with new oil. So much so that I can't even go a full OCI because of it being a Design Flaw.

Edit: a word
 
Last edited:
Not stupid. it's only the "cause" of leaks and sludge because it wasn't maintained or your Dodge didn't design it right.

You can also say, oil filters and oil changes are also "stupid" if you had a car that sludged up because you failed to do an oil or filter change and got a problem.

We could use a lubrication system like 2-stroke where lubrication is provided in the fuel or just dumps out oil onto the ground as it gets used up, and people wouldn't have to remember do an oil change or filter change again. That'd be way smarter then what we do now using that same logic.

sarcasm off.

So if your car has problems, blame dodge for not designing your system well. or blame your maintenance for not replacing a $5 part and/or hoses occasionally.


That being said, you're also blaming something in your 15years old car, and the design for that would be even older. Without seeing if it's still a problem in a modern car.

That's like saying, my motorola Startac phone's hinge is squeaky. They're so stupid for not making out of plastic instead of metal.
 
Last edited:
My M42 in the 91 318i doesnt have a PCV or EGR, but a a result it has a set of breather hoses that are incredible to trace. Count your blessings.
 
In most cars its incredibly cheap, and easy to replace. 10$ and under 10 mins on my car. You can even just clean it with carb spray if you find it wasteful to replace..it could be like JHZR2 said..
 
no, there is a design flaw in the Neon engine. the baffles don't baffle well enough to keep liquid oil out of the PCV system esp under tight right hand turns. catch cans are a not uncommon addition to them, esp in the 2.4l version used in the PT cruser, and turbo'ed in the PT & SRT4 Neon

saying you can't go a full OCI, what oci are you using?
my old Neon(2005 SXT), went 7k on whatever oil/filter was on sale it's first 54k mi as a DFW Commuter car, not using much, then after i bought it, i at first did the old fashioned 3mo/3k mi, but ended up on 6mo/5k mi, but never needed to add more than 1/2-1 qt.

heck the last OC i did on it was 10/2013, and the folks i sold it to have put maybe 1000mi on it since they bought it last feb.
probably still has the MS5K, and M1 Filter i used.
(She took a 4 yr Job in Alaska, and only comes home for about 2 weeks every 6 months or so)
 
Originally Posted By: raytseng
Not stupid. it's only the "cause" of leaks and sludge because it wasn't maintained or your Dodge didn't design it right.

You can also say, oil filters and oil changes are also "stupid" if you had a car that sludged up because you failed to do an oil or filter change and got a problem.

We could use a lubrication system like 2-stroke where lubrication is provided in the fuel or just dumps out oil onto the ground as it gets used up, and people wouldn't have to remember do an oil change or filter change again. That'd be way smarter then what we do now using that same logic.

sarcasm off.

So if your car has problems, blame dodge for not designing your system well. or blame your maintenance for not replacing a $5 part and/or hoses occasionally.


That being said, you're also blaming something in your 15years old car, and the design for that would be even older. Without seeing if it's still a problem in a modern car.

That's like saying, my motorola Startac phone's hinge is squeaky. They're so stupid for not making out of plastic instead of metal.
now you all are hilarious.... take a BP pill asap
 
Well, GM must think a PCV "valve" is stupid, as my 2013 5.3L does not have a PCV valve, but a simple screwed in orifice that a plastic tube attaches to and runs to the intake manifold. Supposedly appropriate baffles in the valve cover. But, the oil catch can I put on the PCV tubing captures about 1 oz of oil in 1000 miles. The engine itself "uses" about 8 oz of oil in 6000 miles, and 6 oz of that is migrating true the PCV line.
 
Originally Posted By: Gokhan
It's not to mention that most people don't like breathing blow-by gas.


Unless you are stopped next to someone at a light, no one would even notice? Maybe the owner themselves occasionally. And a small engine from an owner or two is really not an issue in the broad scheme of things. There are hundreds of thousands of pre-emission commercial vehicles running up and down the road with 13L and larger engines, almost all of them over 500,000 miles, every day that have direct to air crankcase ventilation. CCV did not become part of heavy diesel use until 2007, and there are 2.5 million commercial vehicles on America roads almost every day with a substantial portion of them still with CC to air ventilation.
 
This is the same argument people use for EGR/DI/FI...Catalytic Converters/DPF/SCR....

You are all right lets all go back to points & simple venturi carbs live will never be easier! 2 stroke diesels as well!!!

Nothing wrong with PCV whether it be through a check valve or simple tube but venting to the atmosphere in your own personal vehicle is just plain rude and bad karma.
 
I grew up with points,plugs,rotor button, coil, what the heck and we did not choke to death,,the rest is for sissies and big corps to make more money on,,,,imho.
 
Originally Posted By: Thermo1223
This is the same argument people use for EGR/DI/FI...Catalytic Converters/DPF/SCR....

You are all right lets all go back to points & simple venturi carbs live will never be easier! 2 stroke diesels as well!!!

Nothing wrong with PCV whether it be through a check valve or simple tube but venting to the atmosphere in your own personal vehicle is just plain rude and bad karma.


If you think your car is that much less offensive to the environment with your emission controls in place, route a hose from your tailpipe into your window, sit in the drivers seat, and run your engine.

If vehicle emissions are evil, wrong, or irresponsible, emissions controls make a car only slightly less so, but still all of the above.

Shaming a person for causing more emissions than yourself is the literal equivalent of shaming a person for leaving a bigger pile of feces after you have both finished squatting where you eat.

Just because your turd to the environment is more polished than mine, does not mean it is therefore free of culpability. After all, a vehicles greatest damage to the environment has already occurred before it even rolls off of the assembly line.

Figure in the additional damages caused by having a scrap rate, crash testing losses, transport, etc., and the pro-rated damage caused by the creation of each single new car is even more grievous than the actual single-car damage values would suggest.

But you keep believing you're doing right by the environment. Somebody told you so, so it must be true.
 
Originally Posted By: TiredTrucker
Well, GM must think a PCV "valve" is stupid, as my 2013 5.3L does not have a PCV valve, but a simple screwed in orifice that a plastic tube attaches to and runs to the intake manifold. Supposedly appropriate baffles in the valve cover. But, the oil catch can I put on the PCV tubing captures about 1 oz of oil in 1000 miles. The engine itself "uses" about 8 oz of oil in 6000 miles, and 6 oz of that is migrating true the PCV line.


Its to solve a design flaw in the LS engines since it's introduction. Earlier LS's had a PCV valve but the engine would consume oil through the PCV. They fixed the issue using a fixed .100" orifice that replaces the PCV valve. Newer trucks have it integrated in the valve cover.

The PCV system of pulling crankcase gasses into the intake is stuck in the past IMO. Blowby gases just ends up building up in the intake manifold and intake valves in modern port and direct fuel injection engines. BMW uses an oil separator system.
 
This alleged "design flaw" is present in virtually any engine with a sump! If indeed a PCV represents a design flaw then you have a LOT of work to do to eliminate them! Even BMW's carefully designed oil separator constitutes an effective Positive Crankcase Ventilation system. BTW, there are many thoughtful oil separating devices employed by others also.

Every late model engine with a dry intake has oil in it and on it. For some this means issues but they are a very small minority of total units on the road. This is many millions of cars.

And those GM engines are the WORST! That's why we sell them here with half a million miles on them and still running just fine, good enough to immediately begin working in another state for a new owner. It may also explain why every other mfgr except GM voids their warranty in our kind of service! Hmmmm...

I find it very interesting that we own so many "known oil burners" yet none of them use measurable oil between changes.

And no matter how eloquently you spin it or how hateful you can phrase your denial, advice to remove emissions equipment has no place in responsible ownership. While some of the latest diesels have issues that are easily resolved through barnyard fixes it is irresponsible and ignorant to suggest that you somehow have the right to violate the law just because you feel like it...
 
Last edited:
Originally Posted By: DoubleWasp
Originally Posted By: Thermo1223
This is the same argument people use for EGR/DI/FI...Catalytic Converters/DPF/SCR....

You are all right lets all go back to points & simple venturi carbs live will never be easier! 2 stroke diesels as well!!!

Nothing wrong with PCV whether it be through a check valve or simple tube but venting to the atmosphere in your own personal vehicle is just plain rude and bad karma.


If you think your car is that much less offensive to the environment with your emission controls in place, route a hose from your tailpipe into your window, sit in the drivers seat, and run your engine.

If vehicle emissions are evil, wrong, or irresponsible, emissions controls make a car only slightly less so, but still all of the above.

Shaming a person for causing more emissions than yourself is the literal equivalent of shaming a person for leaving a bigger pile of feces after you have both finished squatting where you eat.

Just because your turd to the environment is more polished than mine, does not mean it is therefore free of culpability. After all, a vehicles greatest damage to the environment has already occurred before it even rolls off of the assembly line.

Figure in the additional damages caused by having a scrap rate, crash testing losses, transport, etc., and the pro-rated damage caused by the creation of each single new car is even more grievous than the actual single-car damage values would suggest.

But you keep believing you're doing right by the environment. Somebody told you so, so it must be true.


Actually, when my Magnum was smogged, it blew zero across the board. No unburned fuel, no NOX, and no carbon monoxide!
 
And, of course the mighty catalytic converter simply converts CO, NO and HC to CO2 and H2O, a known greenhouse gas. In fact, the additional CO2 produced is significant, and worse than that, often nitrous oxide N2O is produced in significant quantities. N2O is said to be 298 times as potent a greenhouse gas as CO2.

We know modern cars are cleaner, by simple observation. What we often fail to discuss are the compounds we now produce vs. modern engines without cats. Also consider that due to catalytic and other requirements, modern engines run at 14.5 to 1 air/fuel ratio. Up to a 25% increase in economy is possible with significantly leaner mixtures.

Another note, direct injection gasoline engines are producing significant quantities of micro particulates. Not unlike diesels. There are horrific claims concerning micro particulates.
 
Status
Not open for further replies.
Back
Top