You seem to be confused about the purpose/operation of the PCV system.
It has no effect on gas mileage and it is not necissarily even an emissions system.
It keeps hydrocarbons in the blowby gas from disolving your engine oil.
It also helps keep seals/gaskets from leaking due to pressure crankcase build up, (better than just a breather since blowby is being sucked out instead of being dependent upon a pressure differential to blow it out a breather).

 

Just put a catch can in line, so much better than eliminating the PCV system. 2nd Generation Neon owners have been doing this for a long time due to the horrible placement of the valve, a hard right turn sends oil right into the intake manifold. A pool of oil in there is not uncommon.

 

A major component of blowby is water vapor. Condense enough of that in the oil and you have sludge and acids forming in the oil. Even the most prehistoric SBC had a crankcase evacuation system using a "draft tube" that hung down under the bottom of the engine an let the vacuum created by the air moving under the car pull the harmful vapor out of the crankcase.

Even hardcore racers adapt the technique by running a hose from the valve cover to an exhaust tube, creating a vacuum to evacuate the vapor. Simply adding a breather, and eliminating the "motivation" (vacuum) that purges the crankcase is useless. The only thing the breather will do is allow the blowby, which would start to pressure the crankcase without a way out, with that way out. Shut the engine down and the crankcase and lifter valley is still full of harmful vapor, which will condense and find its way into your oil.

I can't believe anyone would even consider removing the PCV system, and even harder to believe that someone thinks it an "emissions" system. The only "emissions" feature is "closing" the system so that it vents back to the engine, rather than to the atmosphere.

I use the stock system, no breather and never have oil in the throttle body or intake system. Excessive oil can be caused by a faulty PCV valve or hose allowing the vapor to build up in the crankcase, causing it to flow out the valve cover, picking up oil particles, and backwards through what it supposed to be the air supply tube, to the throttle body. It can also be caused by excessive blowby that exceeds the capacity of the PCV system. Might be time to check the rings.

 

first of all - like it or not it is considered part of a vehicles emissions system. and the only thing i asked is if he was worried about the emissions caused by removing the system - which i am sure you will not argue that it will cause. never at any time did i state that its only function was to reduce emissions, which however is a large portion of its job. to recirculate blow-by gasses through the engine to burn any unused fuel and lower hydrocarbon emissions. i do realize that hydrocarbons mixed with engine oil creates acid - but i believe that changing oil every 3,000 miles or 6 months and breathers on the valvecover will be sufficient

second - in the first post i also recommended a catch can - obviously to be used in-line with the pcv system to keep oil out of the intake

and i will ask the question again - have you ever seen a problem caused by removing the pcv system and replacing with breathers. i have seen so many sytems like that and never once seen a problem caused by it. and i am not talking about something you read in a book - "have you personally ever seen a problem caused by doing this"?

 

Not intending to highjack the thread but I have a question on this also.

Just bought a 95 lt1 (caprice) motor which I'm in the process of swapping into my 3rd gen. Motor has been converted to carb (I know-I know I will get bashed for that)

Anyway the passenger side valve cover has holes for an oil filler and smaller hole for PCV but the drivers side has no holes at all. Shouldn't there be a breather on the drivers side as well?? I was thinking of going with a breather instead of the PCV also until reading this thread now I'm not sure? I've seen so many pics of different setups on the LT1 such as 2 breathers, breather one side PCV other, etc... What would be the best option considering my setup??
Thanks and sorry again for the highjack!

 

No.... I've never seen a removed PCV system cause a problem with an engine.... because in the 50+ years that I've been wrenching on engines, I've never first-hand seen anyone **** enough to remove the system, or even think about removing it. It's just common sense.

Its your engine.. .screw it up any way you want. Just don't let your indifference, or lack of knowledge damage someone else's engine. If you are expecting instantaneous engine failure, you're wrong. Your oil will be contaminated, and things will start to wear faster. How, several years later, will anyone be able to correlate that spun bearing the the lack of a PCV system?

You may enjoy insulting someone for "book learning".... but I don't think the learning that went into becoming a degreed mechancial engineer, and a licensed professional engineer, combined with extensive hands on experience with automobiles and mechanical equipemtn is really such a bad thing.

 

Why not just keep the pcv system and add a breather?

 

The hole in the passenger side valve cover is not for the PCV valve. That's the location for connecting the hose that supplies filtered, MAF measured air from the passenger side of the throttle body to the valve cover. The PCV valve is on the driver's side of the intake manifold, pulling crankcase vapor up through the sheet metal baffle on the bottom of the intake manifold. The PCV vacuum pulls the vapor out, the hose on the passenger side admits clean air to sweep through the crankcase and lifter valley to remove the vapor.

You can run with a breather on either side valve cover, or both. The only real difference between that and the stock system is that the air pulled in through the breather(s) will not have been measured by the MAF sensor. You will have built in a "controlled" vacuum leak. The amount of air bypassing the MAF sensor would, however, be small enough that the PCM can compensate using feedback from the O2 sensors, and adjusting the long trem fuel corrections.

 

Am I the only one here wondering why hes sucking so much oil (blowby) into the intake in the first place? Id run a vacuum pump before id run an evac in the headers. I think I would figure out why I had so much blowby rather than replace a perfectally good evacuation system. (PCV) Eric L

 

There's at least two of us.... I tried to point that out, but it got lost in the rest of the post.

 

I think you might have missed some what of a clue.

First let me say since it appears no one else explained the result of a proper working PCV system. As the pistons move down, they create a positive pressure within the crankcase. The PCV system is a check valve that allows this positive pressure to escape. Thus the letters PCV, Positive Crankcase Ventilation. It then seals off to prevent air from reentering the system when the piston moves up and thus a proper working PCV system causes engines to have a vacuum in the crankcase while it's running.

The first diagnostic tool in looking for a PCV system problem is a manometer. This measures vacuum in inches of mercury or inches of water column.

If you can't find a manometer, any lawn mower shop can order one on the cheap for you. If you get an actual water manometer, there is a reason there is a clamp on the inlet tube. Learn why.

But let me draw your attention to an engine that has an oil leak. Think about the crankcase that is under vacuum and is leaking oil. It either looses its vacuum since the check valve (PCV valve) is bypassed or it is sucking dirt into the engine. Neither of which is a good idea and thus we get to what he said in the very first post. (oil leak)

Even a lawn mower engine that looses crankcase vacuum has a tendency to push oil toward the carb since now the carburetor has a higher vacuum than the crankcase that is now zero vacuum or even positive pressured. See?

 

I actually converted my 1962 Pontiac Catalina from a breather/vent tube to a PCV setup so it wouldn't stink so much idling in traffic. No ill effects what-so-ever.

 

really. i dont think i have ever been to a car show or the drag strip without seeing a few like this. there is even a lt1 in this months gm high tech like this.

i am not insulting you at all. but i personally have a associate degree in automotive technology, ASE master certification, ASE L1 advanced engine performance certification, FORD master certification and also a licensed inspection and emissions mechanic in PA . and honestly more than 85% of what i know has been learned by hands on practical experience. there is no doubt that your a very smart man that knows far more about these cars than i ever will, but for you to insult me in your round about fashion with no first hand experience of the situation other than what you have learned in a book is rather frustrating

so your saying that with a intact PCV system after you shut the vehicle down it will pull the harmful vapors out? how exactly is that possible if the positive ventilation is powered by engine vacuum

personally i use a catch can inline with my pvc system, again like i recommended in the first post. the original poster asked how to delete the pcv system and i answered his question. at no point in time did he ask for anyones elses opinion on this. so maybe in the future we should try to stay on track

and what happened to this insulting comment - did you check your book and realize it is a part of the emissions system

 

Race cars are an exception. Why would they care about long term damage when they tear down the engine frequently?

Let's face it, people see something on a race car and try to emulate it on the street. Not everything seen on a race car is a good idea for daily use.

 

Plus most "race cars" that I've seen use a scavenging setup to lower crankcase pressure and create negative pressure instead of positive pressure using the old-school header tap method or a dry-sump oiling setup.