I understand the benefits from replacing the PCV with a crankcase breather, but are there any drawbacks?

What is the benefit?

By not running the crankcase gasses through the cylinders some (minimal) power is freed up. Also, residue builds up in the intake (probably as it cools in the intake and falls from suspension).

you will still get residue (coking) from open intake vales after the engine is turned off even without a PCV

True, but with a breather will it be as bad? Will it make residue through the entire intake manifold? In the TB?

the only thing I can think of is the PCV actually pulls the gasses, while the breather relies on the gasses being pushed
which basicly means the PCV does a better job

and, while minor: with the breather, the gasses are just realeased. which means in a garage, or while standing still - the air around the running engine gets "oily". That same "build-up" people complain about in the intake is now everywhere else. you breath it in. it coats the engine bay. garage. etc.

Yeah, just leave it.... the engine was designed to run with the PCV in place. Want more power, remove weight from the car.

PCV was first "Emission" device... (Look it up.)
It will cut emissions and extent engine life allot. By removing crankcase fumes, with contains unburnt fuel, cuts oil sludge and make oil itself last longer.
No breather on it's own will do the job like PCV can.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Yeah, there's zero power benefit to removing the PCV system and replacing with a breather. Without positive crankcase ventilation, i.e. using vacuum to pull out the fumes and thus bringing in clean, filtered air, the oil's life will be shortened due to increased contamination.

This brings me to a question I've had. Why does the duke have a PCV valve going to the TB as well as a breather connecting to the intake?

-Michael

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"A guy know's he's in love when he loses interest in his car for a few days." -Tim Allen

He who dies with the most toys... still dies.


My '84 Resto

quote Originally posted by Fierology: This brings me to a question I've had. Why does the duke have a PCV valve going to the TB as well as a breather connecting to the intake?

Not just a breather... Air intake filter for PCV system.
They put a small filter in main intake if the engine gets too much blow-by for PCV can handle. Location of filter is backup for PCV. That way oil etc gets sucked in to engine in two places not all over the engine bay, ground, road,,,,

Many use this kind of "Breather"


And some engines don't use a separate filter. They pull air after main filter.

[This message has been edited by theogre (edited 06-10-2011).]

If an engine, any engine, has a breather replacing its pcv valve, and no oil, or oil vapors seem to be on the breather is something wrong? I have a Buick 350 that has been run that way for 3 years and no oily residue.

quote Originally posted by 2.5: If an engine, any engine, has a breather replacing its pcv valve, and no oil, or oil vapors seem to be on the breather is something wrong? I have a Buick 350 that has been run that way for 3 years and no oily residue.

350 - V8 - so - is there a breather on BOTH sides? or just one? it maybe that there is in fact a PCV on one side, and a breather, which is acting like a fresh air supply, on the other.

quote Originally posted by Pyrthian: 350 - V8 - so - is there a breather on BOTH sides? or just one? it maybe that there is in fact a PCV on one side, and a breather, which is acting like a fresh air supply, on the other.

Actually there is a PCV in the back of the intake I supopse that takes care of it (forgot about that). There is only a breather on one valvecover, the other is sealed. I do think the PCV though is hooked to a vacuum port on the front of the carb and not filtered at all, normal?

quote Originally posted by 2.5: Actually there is a PCV in the back of the intake I supopse that takes care of it (forgot about that). There is only a breather on one valvecover, the other is sealed. I do think the PCV though is hooked to a vacuum port on the front of the carb and not filtered at all, normal?

the Fiero V6 PCV is not filtered either. it just uses baffles in the valve cover to filter the oily air.

Some, usually old, engine have no plumbing to air cleaner.
Any such engine get blow-by too much for PCV can handle then "breather" let all waste product out... Very messy engine and engine bay will result.

Filter not getting oil etc? Is ok. Mean good plumbing design and engine has little to none of ring wear.

In Fiero's 4 cyl, some oil can get thru to filter because no baffle to stop oil having easy access to filter in valve cover.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Ok, EGR will remain. A little carb/TB cleaner is much cheaper than a new bottom end. To heck with the maybe 1 or 2 hp.

Hey you guys....you can run both. WAAAAAAAAAAHT?!?!?! This is correct and I will tell ya how
You know that little thing called a PCV valve that is just ugly to look at? Great! Now pull it off along with the rubber grommet. Oh yea, you need the upper plenum off for this. Got it off? Good. Now remove the big ol vac tube. Is it off? GREAT! So now you have the rattle thing (pcv), grommet, 90 degeree rubber thing to attach rattle thing to sucky vac tube thing. Now what with all these parts? Not so fast speedy! Do you see that tube that connect to the rear valve cover and then to the intake tube? Good, take it off and throw it at the nearest person. Now walk around home depot with the intake tube and ask for a cork that fits in the hole. Get the cork.....Make sure its rubber. Put the cork in the hole and weld it together with a heat gun! Better yet, figure out how to plug your own damn hole. Now you have some random hole in the back of your engine on the valve cover. Random hole can be seen here

Now do this. I will draw a state of the art model in MS paint!
Come to think of it....This pic just about sums it up. If you have any more questions just ask.

EDIT: Heh, i put the valve covers on backwards. This is becoming a friggen time consuming habit.
Here are pics of previous backwards mistakes

[This message has been edited by 87antuzzi (edited 06-11-2011).]

I believe the greatest benefit to breathers in place of the traditional PCV system is on highperformance or forced induction engines. The reason being that they have a tendency to build a greater level of crankcase pressure that may exceed the ability of the stock PCV system to vent it. It's been a while but I recall reading something on the effects of piston ring sealing as it relates to elevated crankcase pressure and this is particularly important to a high mileage engine with worn rings on the intake stroke where pressure in the crankcase may result in oil getting past the rings and into the combustion chamber as it works in unison with the vacuum being pulled in the cylinder at the same time.

So it's best to keep your PCV system in place and install a good oil catch can to help reduce the amount of oil sludge builup in the intake.

I've personally dealt with high crankcase pressure forcing oil out of the turbine end of a turbo as the pressure worked its way up the oil drain. This is not a common occurence unless of course you burn the rings (Yes I did) or, you have a worn or poor sealing turbo.

Another reason a breather is more beneficial on a forced induction or HO motor is that crankcase pressure will work on every seal designed to keep oil in the engine. When I increased crankcase pressure ventillation from the engine a mysterious oil leak disappeared. I had an oil catch can in place that had 3/8" fittings but barely 3/16" passages through them so it actually reduced ventillation from the crankcase and caused a problem.

I recall two configurations for the PCV system, one fed valve cover gasses directly ahead of the throttlebody with a fitting in the flex tubing from the airfilter, and another with a fitting on the airfilter canister itself on the Fiero 2.8.

An easy way to address the carbon/oil build up in the engine would be to use a spray bottle to mist water into the engine while holding the throttle open to a steady rev on occasion. In water/meth injected engines the combustion chambers stay squeaky clean as a result of the steam cleaning from the immediate evaporation process.
Look it up on the net. You will not hydrolock the motor with a mist.

Previous owner put a breather filter on my 2.8 but it also has a vacuum line attached to the side of it and the engine bay is fairly clean. The breather looks like a traditional one for a v8 but has a 90°vacuum port on the side of it. Assuming what you all wrote is it still a good idea to install a stock pcv on it?

quote Originally posted by Pyrthian: the Fiero V6 PCV is not filtered either. it just uses baffles in the valve cover to filter the oily air.

Actually, the air supply for the PVC system on the V6 is filtered, that's what the hose is for that runs from the snorkel to the valve cover. Clean air from the air filter goes through that metal hose, in one valve cover, through the crankcase, out the over valve cover through the PVC valve, and into the intake downstream of the throttle body. BTW, the PVC valve's primary function is to act as a check valve so that an intake backfire can't ignite oil vapors in the crank case. The orifice on the valve acts as a calibrated air leak so that the amount of air entering the intake is a fixed and known amount.

When I had my 06 GTO, there was a can system you could put in place. it still allowed the PVC system to work, but the can filter would trap any dirty oil. The LS2 guys said that it kept oil clean and cut back on the sludge. Wondering if this could be done for the 2.8 V6?