Crankcase Breathers

[Brutus]

I saw where Tucker made ref. to crankcase breathers in his post on his intake kit. I wanted some feedback on the pros and cons of this. I have seen them used quite a bit in some magazines and think they look cool. Is there any benefit to not venting your crankcase into the intake?? Anyone..........Anyone???? Here is a pic

http://www.bakerprecision.com/images/Breather2.gif

[CRUZTAKER]

I did a rest fit of the tube today, and there was no indication of this part....?

I was under the impression, from the install instructions/pictures (I didn't receive the part though), that they supplied a new vent tube to attach to a fitting they put on the intake tube as the OEM doesn't reach.

[Brutus]

I did a rest fit of the tube today, and there was no indication of this part....?

I was under the impression, from the install instructions/pictures (I didn't receive the part though), that they supplied a new vent tube to attach to a fitting they put on the intake tube as the OEM doesn't reach.No Barry, its not in the kit but he made mention of it in his post that he sold them, and It got me thinking. Here is a pic, it is at the front of the valve cover.


http://www.jlttruecoldair.com/images/tn_Productpipe%20026.jpg

[BlackHole]

All its really for is to prevent oil getting into the TB and upper intake by releiving the oilpressure in the crank case. Most 2nd Gen Lightnings have this as a mod. it screws in or tightens with a clamp to the oil cap opening. Don't know if it well work for the DOHC mod motors or not but they work great for the SOHC though. And if you have a custom chip you well need to have it reburned to compensate. for the different oil pressure or your Check engine light well come on plus your ECU well register a engine fault. :revenge: :revenge:

[CRUZTAKER]

No Barry, its not in the kit but he made mention of it in his post that he sold them, and It got me thinking. Here is a pic, it is at the front of the valve cover.
Uhh...missed that one. OK. ;)

[gdmjoe]

Actually, Metco makes a high quality screw-in valve cover breather ( adapter + filter ) that replaces the oil fill cap. Link (http://www.metco-inc.com/valvecvr.shtml)

Picked one up last year ( Metco was a vendor at Fast Fords in the Fall @ Rockingham, NC ), however, haven't installed it. Reason - The PCV is on the same side as the oil fill tube; installing the valve cover breather would mean that un-metered air could be induced into the air intake since the PCV connection is after the MAF ( and its readings ).

[BillyGman]

whatever you do, don't ever replace the PCV valve w/a breather like that. I did that on my Vette and immediately began to have a problem w/oil leaking out from where the intake manifold meets the engine block. I later found out that unless you're going to weld a special bung in your header collectors w/a one way check valve and a tube that leads to the breathers, then eliminating your PCV valve in order to replace it w/a breather causes excessive pressure to build-up in the engine crankcase which will often cause oil leaks. I'm not sure if this applies directly to what you're talking about here, but because it's very common for performance enthusiasts to attempt to eliminate the PCV valve by replacing it w/a breather, atleast on carbureted engines, I thought it would be helpful to someone for me to point this out.

[Warpath]

I did it on my Cobra. Here's what I picked up off the internet:

Pros:
1. It prevents oil from getting sucked into the intake (the reason I did it) especially on blown engines. I found my upper intake cover had carbon build up. The only source of this carbon would be from engine oil. I've also been told by a shop that the oil can cause detonation. Also, removing the oil from the intake creates cleaner incoming air which will burn better.
2. It supposedly adds hp. Of course those who stated it also mentioned they seen dyno results but never posted any. So, I don't know if that is true. I understand it will rob hp on high reving engines (>10k rpm) since having the crankcase connected to the intake will lower crankcase pressure and help seat the piston rings. I don't have any proof of that either.

Cons:

1. It makes the interior smell like exhaust. Some Mustang owners ran a tube into the fender then attached the filter to eliminate the exhaust smell. Eventually, I'll do that.
2. Some have mentioned unmetered air getting into the engine. If you plug all the other holes, I don't understand how that would happen. But, I'm no expert.
3. Someone mentioned they may increase emmisions. I have no proof again. But, I thought I'd better mention it for those of you with emmisions laws.

I installed the breathers and pluged the other holes and, so far, no problems or leaks (knock on wood). As I stated, it was for peace of mind that I wasn't sucking in oil to the intake.

[BillyGman]

I'm not sure if I understand what this breather set-up mentioned actually is. Is this one of thoise that eliminates and replaces the PCV valve? if it is, then although it also eliminates oil from entering the intake system, and from getting into the fuel/air charge, it is NOT good for a street engine. Elimination of the PCV valve comes from racers doing that. but what these companies that sell these things don't tell you is that many racing engines actually have vacume pumps that draw the pressure from the crankcase out. And these vacume pumps are belt driven. The reason for that is because if you just slap a breather on there in place of the PCV valve, you eventually will have a build-up of oil pressure in the crankcase, and either oil will be forced past the piston rinfgs into the combustion chamber anyway, or you'll eventually have oil leaks somewhere like I've pointed out in my previous post.


The exfeption to that rule is perhaps some drag racing engines that see short run times. Another way that racers do this is the bung welded in the header collectors that contains the one-way check valve inside, which allows the vacume created by the exhaust flow to draw the crankase pressure out through the exhaust via a tube or hose that goes from that header collector one-way check valve to the valve cover breathers. Summit racing sells both the header collector bung w/the check valves, as well as the vacume pumps that ate belt driven. there us good reason why these things are sold!! Because if you eliminate the PCV valve, then you're going to need these things. If you don't incorporate them, then you're going to have problems down the road!!! Not a good modification here. Unless ofcourse my assumption is wrong, and this mod does NOT eliminate the PCV valve.

[Brutus]

I did it on my Cobra. Here's what I picked up off the internet:

Pros:
1. It prevents oil from getting sucked into the intake (the reason I did it) especially on blown engines. I found my upper intake cover had carbon build up. The only source of this carbon would be from engine oil. I've also been told by a shop that the oil can cause detonation. Also, removing the oil from the intake creates cleaner incoming air which will burn better.
2. It supposedly adds hp. Of course those who stated it also mentioned they seen dyno results but never posted any. So, I don't know if that is true. I understand it will rob hp on high reving engines (>10k rpm) since having the crankcase connected to the intake will lower crankcase pressure and help seat the piston rings. I don't have any proof of that either.

Cons:

1. It makes the interior smell like exhaust. Some Mustang owners ran a tube into the fender then attached the filter to eliminate the exhaust smell. Eventually, I'll do that.
2. Some have mentioned unmetered air getting into the engine. If you plug all the other holes, I don't understand how that would happen. But, I'm no expert.
3. Someone mentioned they may increase emmisions. I have no proof again. But, I thought I'd better mention it for those of you with emmisions laws.

I installed the breathers and pluged the other holes and, so far, no problems or leaks (knock on wood). As I stated, it was for peace of mind that I wasn't sucking in oil to the intake.
Thanks for the input!! That is the same line of thinking as me. When you did it to your Cobra you didnt actually do away with the PCV valve, correct?

[BillyGman]

When you did it to your Cobra you didnt actually do away with the PCV valve, correct?GOOD question!!!! The answer is important!!!! If there's mention of the kit preventing oil from getting into the intake as he mentioned in his post, then that usually means that the PCV valve was eliminated, since it IS the PCV valve that can sometimes allow oil to enter the intake manifold. However a PCV valve is a neccessary evil on street engines unless you have the header collector bungs w/the one-way check valves that I've mentioned. But we need a definate answer on this!!!!

[jaywish]

Well color me confused.

I remember the old days before PCV valves.

The whole idea of breathers is to allow any pressure in the crankcase to escape. Plus let out some of that nasty smoke that passes the rings. It sure was easier to spot a tired engine by the smoke comming out.

Positive Crankcase ventilation keeps the engine cleaner on the inside by power venting the crankcase. The valve part of it is what allows the engine vacum to be used to suck out the nasty gases. In this system those nastys get burned by the motor. This is the way pollutants can get into the intake system, by the PCV valve.

You can get the suck out effect, which is really important in keeping your motor clean, with a seprate pump of some kind but pollution increases since the nastys don't get burned just vented out to the air.

Well maybe I'm wrong about all this but that is what I learned quite a long time ago.

Jay

[FordNut]

Well color me confused.

I remember the old days before PCV valves.

The whole idea of breathers is to allow any pressure in the crankcase to escape. Plus let out some of that nasty smoke that passes the rings. It sure was easier to spot a tired engine by the smoke comming out.

Positive Crankcase ventilation keeps the engine cleaner on the inside by power venting the crankcase. The valve part of it is what allows the engine vacum to be used to suck out the nasty gases. In this system those nastys get burned by the motor. This is the way pollutants can get into the intake system, by the PCV valve.

You can get the suck out effect, which is really important in keeping your motor clean, with a seprate pump of some kind but pollution increases since the nastys don't get burned just vented out to the air.

Well maybe I'm wrong about all this but that is what I learned quite a long time ago.

Jay
Yep. More effective crankcase ventilation by leaving the pcv valve intact. You could have smog certification problems if you live in an area that tests. And since the blow-by is being vented into the atmosphere you will contribute to the smog for the rest of us to see and breathe. And since the blow-by is coming out the breather it's going to make an oily mess near the breather on the outside of the engine instead of keeping it inside the engine.

[BillyGman]

Here's a link to the Summit racing webpage which displays the only thing that should be ever used to eliminate the PCV valve. This is the only way to go if you want to avoid oil leaks from increased crankcase pressure. And forget those vacume pumps since they have to be cleaned of oil very often which wouldn't be good for street use. but the kit below is for cars w/headers and requires holes to be bored in the header collectors and welding to be performed. So the headers need to be off taken off, or the work should be done when purchasing the headers. if you don't eliminate the PCV valve w/these, then don't eliminate it at all.

http://store.summitracing.com/default.asp?target=esearch.asp&N=110&Ntk=KeywordSearch&Ntt=header+check+valves&x=14&y=15

[Warpath]

PCV is gone. I pulled the valve and tubes out of the heads and intake and replaced them with APC breathers. I pluged the remaining holes. I don't have a picture. I'll take one when I get home if I remember.

I can't say Billy is incorrect. All I can say is that Pande at Pande Performance told me the first thing they do is yank it out since it draws in oil. Also, Lidio built my engine and he didn't express concern about oil leaks or excessive pressure. He did mention the unwanted smell and unmetered air. Lastly, FWIW, there were some people on corral.net who have been running w/o PCVs and only breathers for several 10s of 1000s of miles with no issues.

Some people have placed oil traps in the lines before the intake to remove any oil which is sucked out. I may try that one day.

The breathers will allow the crankcase to vent when the crankcase pressure gets over 1 atmosphere. When I first start the engine, a little smoke will come out of them. It stops when the engine is hot and the pistons expand.

Another thing - I mentioned the carbon build up is from oil. I forgot about EGR. It may have produced the carbon build up. I don't have EGR hooked up anymore either.

[Warpath]

I should add that I wasn't too crazy about doing it in the first place. But, when my engine was damaged, I noticed a crazy amount of oil being sucked into the blower. I think the oil was being blown into the intake tubing because the pistons were cracked creating a great deal of crank case pressure. But, it made me concerned about sucking oil into the intake which is a greater fear than running the breathers. Its a compromise to me.

[BillyGman]

I can't say Billy is incorrect. All I can say is that Pande at Pande Performance told me the first thing they do is yank it out since it draws in oil. Also, Lidio built my engine and he didn't express concern about oil leaks or excessive pressure. He did mention the unwanted smell and unmetered air. Lastly, FWIW, there were some people on corral.net who have been running w/o PCVs and only breathers for several 10s of 1000s of miles with no issues.


Thanks for your post Warpath. Just remember that there seem to be many serious racers on the corral.net board, and the modification kit that I posted a pic and a link to from Summit Racing in my previous post is what most serious racers use, which BTW is why Summit Racing stocks that kit. That is the best and most legitimate way to prevent oil from getting into the intake charge.

[Warpath]

Both Pande and Lidio knew my Cobra is street only. I haven't checked on corral.net in a while (too busy). So, I don't know the latest info. But, I don't remember anyone running vaccuum pumps. There were some looking for 100% duty cycle pumps with no success. They may have been looking for electric pumps. I was not planning to run one so I didn't pay much attention.

I guess an added con to this mod are the unknowns. You do it at your own risk. Personally, I think if you stay N/A, don't bother with breathers. Otherwise, buyer beware.

I didn't get a chance to check out that Summit kit. I will when I get a chance.

[BillyGman]

No Warpath, I'm not talking about the vacume pump. That wouldn't be practical for the street since it costs about $400, and it has to be cleaned of oil very often. I'm talking about the header bungs being welded in the collectors w/the one-way check valves which enables you to use the exhaust flow as a vacume. That's what all the serious racers do. You don't even have to go to the Summit Racing site because I posted a pic in one of my previous posts. Apparently you didn't see it, so here it is again......

[Warpath]

Oh. I missed the part about the vaccuum pump in your other post. I suppose an oil trap could be put in place to prevent oil from getting into it. You'd just have to drain it every so often. I caught the rest of your post originally. But, I got distracted and forgot it (I was at work). Thanks for the clarification.

That Summit kit looks like a good idea. I think it would work anyplace in the exhaust as long as the exhaust velocity is high. Although, connected to the headers would allow any oil to be burned off in the cats. But, since I'm cursed with a miniscule engine compartment, I have to lift the engine or drop the K member to remove the headers.

[BillyGman]

The time to install that modification that I've been talking about is when you purchase the headers, and before they're installed. And there's nothing novel nor new about this idea. This isn't by any means something that Summit racing has come up with, but it's been something that racers have been doing for years. Infact the kit that Summit Racing offers for this is made by a company named Moroso. Uhmm, you might have heard of them before. :D


But my point is that if someone's going to decide to eliminate the PCV valve, then they should do it the right way. And this is the right way to do it. If you look at magazine article write-ups that have pics of featured race cars that have V8 gasoline engines that are pushing serious HP, then you'll see that many of them have this same modifcation performed to the header collectors and valve covers in order to eliminate the oil getting into the fuel/air charge via the PCV valve. However there have been some aftermarket companies recently who offer some rather half-baked cheesy alternatives to that approach which any serious racer of a V8 powered RWD high HP track car would never endorse.

[David Morton]

Well, I am an expert, factory trained by GM and an ASE Master certified technician which includes tune-up. The Positive Crankcase Ventilation system works like this: crankcase vapors (blow-by gasses) are pulled into the intake charge through the PCV valve to be burned instead of vented to the air. There is not enough of this blow-by to overcome the capacity of the valve to take it all in (by design), so, in order to keep the crankcase from operating in a vacuum, some ventilation is needed. The manufacturers have allowed for this by running a tube from the 'other' valve cover (in our case, as most, the PCV valve inserts into a grommet in one valve cover) and into the filtered air side of the intake tube, upstream of the throttle body. So please let me help clear up some misconceptions here.

1)This is supposed to replace the PCV valve, which is a bad thing for horsepower.
This better not be designed to be used for that purpose because the law prohibits manufacturers from making things designed to disable emissions equipment. EPA will shut them down. As to the PCV being bad for HP, first, oily vapors have proved to be a very good thing for intake valve stem life and for upper compression rings as well. And, if water vapor helps effective octane value of the charge, why would these gases be bad? I know of no reputable authority that says this small amount of gas and oil is causing HP loss. If anything it helps fuel efficiency (recycling the escaped fuel mix) and adds life to the parts exposed to the vapors.

2)Putting this "breather" on the valve cover prevents oil from getting into the throttle body.
The only two ways oil can get into the throttle body through this tube is if the PCV valve is malfunctioning or if the compression rings are toasted, aka, the engine is "blown".

And if this is happening, guess where all that oil is going to be with this "breather" sticking out of your valve cover. Did somebody say "a little smoke will come out of them."?! Tell us about it in 10,000 miles when this "little smoke" has become a greasy mess that has degraded all of your coolant and vacuum hoses.

Honestly, sometimes I get frustrated with the silly stuff people come up with to re-engineer a system that works perfectly. I think the main appeal of this piece of junk is that it is another 'thingy' sticking out that looks cool, costs money and has a nostalgic aura about it. Once comitted, people will say anything to justify the crap they've bought into. Glad they are the ones having one more maintenance item to take care of, the filter, not me.

Have fun, boys. I'll be saving my money for real improvements like a Trilogy Supercharger.

[BillyGman]

I agree with you on that David. It seems that some modifications are simply invented for the sole cause of making $$, and do nothing for the target customers. And in turn some people seem to want to make a modification just for the sake of modifying their vehicle. I mean no offence to anyone here, but this just isn't a good mod IMO on a hi-tech street engine which also has many emissions devices.


David, the points that you made about lubrication I've never thought about. I wouldn't think that's the case, but I cannot claim that you're wrong about that so I'll assume that you're correct. But as far as oil, I remember seeing a puddle of oil contanimated fuel on the floor of the intake manifold on my 73 Vette engine more than once when I had the carburetor off. I could tell it had oil in it because of the color, and I did run a PCV valve. But that might be irrelavent here since that was a simple Low-tech engine w/out many emission devices at all. The only one being the PCV valve itself. No EGR, no cats, nothing.

[Marauderjack]

PCV valves extend engine life exponentially!!

The PCV system was designed and proven many years ago by the US military. In depth evaluation with very scientific data has proven that "sweeping" low boiling contaminants (blow-by) and moisture out of the crank case will extend bearing life 10x and oil change intervals can be much longer since major sources of contamination are removed and burned in the cylinders....harmlessly expelled through the exhaust. :cool:

Granted, "Race Engines" are set up with "open" crank case venting or vacuum systems to ensure minimal crank case pressure thus maximum HP!! Keep in mind that contaminants don't come into play in true "Race Engines" since they are only run a few hours before rebuild or replacement!! :beer:

Do yourself a BIG favor and leave the PCV system in place!! Work toward "Mods" that make sense. :burnout:

Marauderjack :D

[Brutus]

I found this while doing my research:





Theres a right and a wrong way to bypass your PCV (Positive Crankcase Ventilation) system. Before we show you the how to, lets first understand the function of the PCV system. The PCV system is intended to relieve the crankcase of any positive pressure by allowing it to vent through the free flow of air, either into or out of the crankcase. Prior to advent of emissions, the crankcase was just vented through a breather on the valve covers or intake manifold to the environment. Emissions requirements necessitated a “cleaner” way to vent the crankcase to prevent the hot oil laden vapors from damaging air quality. That led to the inclusion of today’s modern PCV systems. Current PCV systems are still pretty simple, consisting of an air inlet, a valve, and an outlet. The air inlet (the vent tube) supplies filtered and metered airflow into the crankcase. The PCV valve, which when opened by either internal intake manifold vacuum or positive crankcase pressure, vents into the intake manifold, allowing the now oil contaminated but otherwise filtered and metered crankcase ventilation airflow to be consumed by normal combustion processes.






Its important to note 2 significant issues:


1) The crankcase ventilation airflow is metered since the vent tube is located after the MAF. Because the airflow is metered, it must make it into the intake manifold to assure that the air/fuel ratio is correct. Therefore, if we bypass the PCV system, it must done in such way that no unmetered air can reach the intake manifold, for if it does, the air/fuel ratio will be adversely affected. Similarly, any metered airflow in the PCV system must make it all the way to the intake for the same reason. What this means is, if you bypass the PCV system, it must be bypassed completely, both the inlet and the outlet air transfer paths must be blocked. You just can’t block off one and not the other.


2) The PCV valve is intended to be opened by intake manifold vacuum (negative pressure), but can also be opened by positive crankcase pressure. Therefore, whenever vacuum is present in the intake manifold, the crankcase pressure will vent into the manifold and the ventilation air is “drawn” into the intake manifold through the PCV valve all the way through the crankcase, vent tube, MAF, and air filter. Furthermore, when positive crankcase pressure is present, it will be vented through the PCV valve into the intake manifold. There’s no problem at all under most circumstances, but there can be very significant issues in certain applications, especially if substantial cylinder blowby is present, if the PCV system is overly effective, or if supercharged. Who needs to bypass the PCV system? In most applications, the PCV system works just fine, but certain hipo applications may run better with the PCV system bypassed, even though your car will no longer be emissions legal. In that case, the decision is yours, bypass the PCV or remain emissions legal? High compression engines setup with low tension oil control rings are a real good application for PCV bypass. Engines with poor ring seal and substantial blowby will also benefit because the incoming air charge will not be oil laden, which effectively lowers the octane of the air/fuel mixture and increases susceptibility to pre-ignition, detonation, etc. The 99-up models seem to have acute issues with overly effective PCV systems, just about every intake manifold we’ve seen has been thoroughly soaked with oil. In fact, Ford issued a service bulletin for valve cover replacement reportedly using revised baffling to minimize oil contamination of the air charge. However, we think that has been ineffective. More on that later.

[jaywish]

Hi Brutus,

Where did you find that info?

The concern about overly effective PCV systems could be important.

Thanks
Jay

[Warpath]

...Infact the kit that Summit Racing offers for this is made by a company named Moroso. Uhmm, you might have heard of them before. :D ....However there have been some aftermarket companies recently who offer some rather half-baked cheesy alternatives to that approach which any serious racer of a V8 powered RWD high HP track car would never endorse.

Yeah, that name rings a bell. :) There were a couple of posts on corral.net where people bought air compressor oil traps and put them in line with the PCV system. Talk about cheesey.

I'm the one with the "little smoke." It disappears in a few minutes at the same time the piston slap disappears. I have forged internals. Also, if I was concerned about emissions, I wouldn't have done half the mods I have.

Anyway, these posts are the first I've heard of replacing the PCV with breathers as being damaging. I have every other hole plugged. So, the only thing open is through the filter. I can't disagree with any of these posts since I am not educated enough. However, most of what I heard is repeated in Brutus's post. I'll leave the breathers in for now. I trust those whom I contacted. They were only $15-$20 and putting them in was free. So, no big loss out of the mod fund.

[BillyGman]

Warpath, I can't say that I agree with you on this, but I want to thank you for having a good attitude about this discussion in the midst of my disagreement, and for allowing me to voice my opposition. I appreciate your mature approach in this discussion. I sincerely mean that (no sarcasm intended here).

[Brutus]

Hi Brutus,

Where did you find that info?

The concern about overly effective PCV systems could be important.

Thanks
Jay
Sent you a PM

[Warpath]

Brutus - Can you please post or PM that info to me as well regarding your post. I'm interested in it too.


Warpath, I can't say that I agree with you on this, but I want to thank you for having a good attitude about this discussion in the midst of my disagreement, and for allowing me to voice my opposition. I appreciate your mature approach in this discussion. I sincerely mean that (no sarcasm intended here).

You're welcome. People can think what they want about me. So, I don't ever take these discussions personally and I'm not looking to be considered an expert. I try to be the devil's advocate and state that every mod has its consequences regardless of what anyone says. I missed that this time. I find it a bit disturbing, for example, that people put these big wheels with rubber bands on their cars and don't know or don't care that the suspension may come apart from the abuse. I hear that..... Ah, I've babbled on long enough. Sorry to depart from the topic of the thread.

[David Morton]

... I remember seeing a puddle of oil contanimated fuel on the floor of the intake manifold on my 73 Vette engine more than once when I had the carburetor off. I could tell it had oil in it because of the color, and I did run a PCV valve.Yeah, I've seen a lot of that in the early PCV systems that were typically done in the dumbest of configurations, like on your old 'Vette, valve at the back of the manifold coming from an inadequately baffled valve cover bringing in splash oil from the pushrods. As long as oil consumption wasn't a problem, engineering (which I believe resented the mandated emissions systems) didn't care.

Today, most manufacturers have well designed systems that distribute well baffled vapors only because they are consumer satisfaction driven and the improved reliability on PCV equipped engines is an accepted fact that is taught in Emissions 101.

BTW, replace the PCV valve every 10,000 miles whether it needs it or not and you will never have any problems from the system. It's cheap insurance and too easy to replace.

[BillyGman]

I had aftermarket valve covers, and I moved the PCV valve to the front position on the valve cover, but yes, they weren't baffled to well, so the oil went right through the tube that led to an intake vacume port on the base of the Holley Double pumper carb that I was running. Not an efficient set-up to say the least. The car ran mid 13's, but it was a pig on gas (10.5 MPG!!!).