Venting PCV and Oil contamination.

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Something is wrong if you need to change the PCV on a ka24de that often. I had a 1998 Altima SE that was auto crossed fairly frequently, and I never replaced the PCV in 176,000 miles. The car burned zero oil on 6k OCI with GC, even when raced. One of the club members had a 240sx with a turbo, and 130k miles on, he said he never touched the PCV valve. If the PCV is plugging up that fast, you have some serious blow by.

Running a negative crankcase pressure helps improve power by reducing crankcase pumping losses. As the pistons move down, they create pressure in the crankcase.

With the engine warm and at idle, remove the oil filler cap. If the idle drops slightly and there is a minimal amount of air coming out the cap hole, you have minimal blow by. If the idle stays the same and there is lots of air coming out, you have severe blow by. There are always vapors in the engine, it means there is nothing wrong. Piston rings never have a perfect 100% seal, there is always some gasses leaking past.

If you really have a plugged PCV every oil change, you some some serious mechanical issues, and catch cans, road tubes and the like will not really help much until the mechanical issue is corrected.
 
I think what he means is that instead of the PCV valve venting into the air box like most car's he wants to put a small K&N filter on the hose end and vent it to atmosphere that way. I do not think he means the old metal push in crome vent caps in the valve cover's like old cars from the 1960's and such. So he intends to keep the PCV in the valve cover and just vent the house to atmosphere. PCV is not a positive pressure all the time hence the one way valve if you vent to open air with out the valve and a filter their will be times you are sucking in dirt. Also some engines are designed so that they do not run properly if the PCV is messed with they get reading on the vaccum side of things that are erratic and too low. My wife's car does not run that well if I remove the PCV and just leave it out. It will run just not as well.Different designs have different tolerance for this type of thing.

Since 1988 I can count on 1 hand how many PCV's I have replaced on car's. I always clean with carb cleaner each time I change oil and put them back in. So about 1 PCV valve somtime between 150,000-300,000 is my norm. The only vechile I have ever had one fail on is the wifes 1997 Buick like everything on that car it has had to be replaced before the car even had 120,000 miles!
 
Originally Posted By: JohnBrowning
I think what he means is that instead of the PCV valve venting into the air box like most car's he wants to put a small K&N filter on the hose end and vent it to atmosphere that way.


Crankcase fumes contain unburnt hydrocarbons (unburnt gasoline, CO and very small particles of oil). These all are major pollutants. It is much better to run them back through the engine to be burnt. Most of this material will get by both a K&N filter and/or a "catch can".

If you have excessive blow-by or some other problem you can get to the point of burning excessive oil but these should not be an issue on any properly maintained vehicle.
 
PCV systems were pretty much standardized back when most cars had carburetors.
The fuel/air washed the manifold clean.
Now , with fuel injection, manifolds and throttle bodies can get dirty from PCV flow and incidental hot soak vapors from the residue.
This is why catch cans are a good idea.
Factories can't install them, as they call for frequent maintenance that would never be tolerated or performed by the average citizen.
 
mva no offense intended but I could care less about a few PCV related hydrocarbons venting tothe air. Have looked at how any Cadilac and Saturns have black bumpers from oil burning? I was behind a Malibu that was not more then 12 months old and when the guy steped onthe gas to pass oil smoke was coming out the exhast. Outside those states that have California emissions most people in the USA are driving some serious polluting vehicles as in not replacing cat's when they fail just welding a bung and strait pipe in place, not keeping the vehicle in a state of good tune, not keeping air filters replaced as needed, not replacing PCV valves so they turn into oil burning machines from hati etc..........I see all kinds of vehicles here in Michigan and in Georgia that would not be allowed on the roads in California and would not pass a Germany car inspection either!

If I recall correctly most modern car's that are in a proper state of tune produce something like 72% fewer emissions then they did pre-clean air laws! SO I honest do not see automotive emissions as a primary source of pollution.

If you really want to clean things up then get China to put less pollution from their plants into the air and get Mexico to clean up it's act! Switch us over from coal to Nuke power and get all the cows in the world to put methane catalyst in their buts! Oh and get termites to clean up their methane and co2 emissions as well!

The car both gas and diesel have been happered enough by the EPA it is not going to get much better so find another dog to beat because the car is is dead and in the ground.....Even new big rigs have all kinds of particulate filters and egr's etc......

On top of that if they vent to the exhast their should be at least to cat's behind it to finish it off! My I4 has two pup cat's in the exhast manifold and two more down stream I think the two down stream kats can handle a little bit of PVC gases with out causeing the end of the world as we know it!

P.S. London in the 1400-1800's hadno cars but had some of the worst pollution in the history of mankind! Guess those British should of frozen to death or put catalytic converters and PCV valves on their smoke stacks!LOL

Just like Peak oil has been proven wrong......I said it when it first showed up on this site it was rubish!Global Warming is equaly bad science!
 
Word. I think sucking in the oil cycling it countless times in the cylinders and blowing it out the tail pipe is worse than venting pressure that has little to no residue accompany it.

I have both ports openly vented and the past 100 miles I have not seen a drop of residue come out of the hoses. I have also not smelt the stench of vapors I used to with a PCV valve and catch can.

Even with the catch can I have oil still got burned in the engine and it smelled horrible when it blew out the exhaust.

Pollution is not an issue, thats another topic, the topic here is oil contamination and moisture in the crank case in cold weather.

Ive heard of people passing smog with a bypassed PCV and EGR system.
 
I don't know of anyone passing Emissions without a PCV/EGR.
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Can't say I have ever done it for friends...
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No one even commented on the thermostat. Hello?

If those cylinder walls don't get a little temp you'll never get a good long wearing seal at the rings.

massive blow by is a common problem, and a properly sized PCV setup with a catch can will work on any vehicle with an internal combustion engine without performance penalty.

In my boat is a very loosely set up Chevy stroker big block with a positive displacement supercharger. Purpose built for my app. Makes about 850 HP and will get some serious blow by with the boost ramped up. We use some large diameter hoses and a big catch can.

Keep working on it, you can lick it with some better engineering, and StevieC has provided excellent tips.
 
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