kenhebe

I was curious to know if there would be a negative side effect to me installing an oil breather on the valve cover and eliminating the PCV hose that runs from the valve cover into the intake. I figured that it is not doing anything but pulling hot oily air into the air intake so if I eliminate it completely and jsut install an oil breather on the valve cover that would work. Thoughts?

FASTL61

i have done the same no effects

Silv3r

I've heard some get CEL's from having the breather filter on, but someone will have to back me up with some info/evidence.

Just do a catch can mod.. https://www.cobaltss.net/forums/general-cobalt-68/catch-can-update-96499/
There used to be a how-to but it got deleted it seems.

Shermen

i used to have it done on my SS/SC, no cels or anything, i put a gready catch can on now. i used a little stumpy rubber thing and a hose clamp on the intake pipe side to plug the hole.

Johnboy12358

I was looking for this how to the other day, wonder why its gone...

Cobaltxfe09

ive done this also on my 2.2 no problems here

leviticus88

I know nothing about catch cans, can you point me in the right direction? My throttle body and intake is always dirty.

kenhebe

I am well aware of the catch can thing as I am the originator of the idea on this site. I did not do the how to, but I was the first to do it. With the cathch can though, your air intake is still sucking in hot air from the top of the motor. By eliminating that whole system and just putting a breather filter on my valve cover and capping off the stub on my cold air intake, I was able to lower my both my intake air temp 2 by 9 degrees. Good mod for $10

csementuh

iTrader: (18)

You could just do an oil cap breather...

impulseballer

yours is kind of redundant because you still have the breather from the intake pipe also. unless your pushing very high boost you wouldn't need both. i saw u have the 2.7 but you still probably don't need both.

ps i removed the hose and put a breather on so I didn't have to tap my beautiful rdfabs one piece.

Jplaya023

i was looking into doing this...what do i put on the other end of my intake inlet pipe because i have the gmpp intake and its got a huge nipple poking out if it to connect the hose too and im not positive what to connect the there

csementuh

iTrader: (18)

The stock line is not a "breather", it is vacuum line recirculating to the intake tract similar to a PCV system without the valve. I doubt the breather is "redundant"... You might not "need" the stock vacuum line running into the intake, but I haven't felt like removing it, and it certainly isn't hurting anything. In fact it's likely barely moving any oily air with the large breather installed, so a catch can is likely unnecessary in the stock line with my setup. People have problems with the stock LSJ's blowby bad enough to pop the dipstick out, I'd venture a guess that 18 pounds of boost certainly isn't "hurt" with a breather...

Comments? Recommendations?

impulseballer

i was under the impression that air goes into that hose not out of it. so if that's the case it is a breather.

Witt

If you remove that line or put a breather on the valve cover you just put an air leak into the intake system. It has about the same effect as drilling a hole in the intake pipe after the MAF.

It doesn't pull air from the PCV bypass pipe, it pulls air from the intake manifold through a hole drilled between intake port 2 and 3. The line running to the intake pipe pulls vacuum and replaces the air drawn from the crankcase into the intake manifold.

1badBlueberrySC

small crankcase breather on mine, with vacuum line removed! NO CELS

Edubs

I had my RD Fabs intake made w/o the return line. Threw a breather on the vc and haven't had any issues in 20K miles...

csementuh

iTrader: (18)

The oily air is pulled from the valve cover into the intake piping through that line via the vacuum created in the intake piping.

I believe that capping off the nipple in the intake piping and putting a breather filter on the valve cover is essentially the same thing as I did with the oil cap breather, although it require no other modification to anything... It will also still pull some vacuum through the stock line and keep everything in check.

Also FYI, modifying the line, removing the line, breathers, etc, are all modifying emissions equipment, and will make your car fail emissions... If you care...

Edubs

I pass emission testing every year. It's all about knowing which shop to go to...

csementuh

iTrader: (18)

I understand that... But it does not legally pass a visual inspection... (not like anyone gives a **** anyways) That was just a warning for n00bs...

My 69' Chevelle SS also passes inspection every year when I drive it over to my buddy's shop, and he goes "lookin' good man... looks mechanically sound" and slaps a window sticker on it...

Witt

That isnt correct. Its pulled from the head through the intake manifold. The air pulled from there is replaced with air in the intake pipe through the bypass line to the valve cover.

Again, when you put a breather filter on the valve cover or remove that line, you are allowing unmetered air to enter the intake pipe through the intake manifold. Since the engine is ingesting the air drawn through the intake manifold from the crankcase its now being replaced with air from the atmosphere that hasnt passed over the MAF.

csementuh

iTrader: (18)

Al, I'm a bit confused... Is *MY* setup OK or not..? I have only the oil cap breather installed. The stock "bypass line" is intact.

If you were getting excessive unmetered air, wouldn't that throw a code? I know before I had a leak in the IM and got a code for it. Also I monitor my wideband and don't go lean...

The time I saw your engine, I though I recall you having a similar setup on yours? An oil cap breather?

Can you please state the correct method of doing this...

kenhebe

I installed the breather on the valve cover and capped off the nipple on the intake so that there is no unmetered air going through the intake. So what is wrong with that?

Bika

iTrader: (3)

If i understand this, you're saying that with the intake port blocked off, and a filter placed on the valve cover port, the engine will ingest atomspheric air through the valve cover breather?
If this is true, the only way to mod this would be an inline catch can.

[valve cover]--->[catch can]--->[intake]

csementuh

iTrader: (18)

Isn't the whole point of the valve cover breather mod to vent crankcase gases out of the motor so that the blowby gases trapped in the crankcase do not give the piston more resistance to push against...?

If soo, what is the *CORRECT* way to do this mod so that it is beneficial...???

impulseballer

i thought the same thing.