oil breather cap - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

Emvici · 09-19-2015, 07:52 AM

I was reading a post this morning from someone that was experiencing an oil leak due to excessive pressure in the block. They had mentioned they replaced the oem oil cap with a breathable one. This sounds like a great idea, but I wanted to run it past who ever might be knowledgeable out there on the concept. Is it a good idea?, Can it throw anything off, with the compression or in the combustion chamber?. If it is a good idea, can anyone recommend one?. and Lastly how much can I expect to pay for a relatively good one? thanks to all, happy trails.

FunkedOut · 09-19-2015, 08:23 AM

pressure in the crankcase is a result of blow by.
the blow by is a result of combustion.
combustion is a result of spark, fuel and metered air. that means the ECU knows how much air entered the engine.

the PCV system should route the crankcase pressure back into the intake.
if the breather cap allows it to escape to the atmosphere, the ECU thinks there's more air in the engine than there really is, and will command too much fuel, making you run rich.

eta: actually, the blowby enters the intake post meter, displacing volume that would've otherwise been filled with fresh metered air. the blowby is generally void of O2 so fuel calcs are good. a breather cap eliminates this, but also allows unmetered air to enter the intake via the PCV system, altering fuel mixtures.

if this happens in closed loop, the narrowband O2 sensors may be able to compensate, depending on the amount of air leaving the breather cap and the amount of trims left in the ECU.

most likely, excessive blow by happens at WOT, where the engine runs in open loop, and the commanded afr is rich. only way to know how much is to measure with a wideband O2 sensor.

Emvici · 09-19-2015, 08:28 AM

I am using an Apex oil catch can, because when you started talking about the combustion blow-by it made me think of the catch can. Does this catch can essential do what the breathable cap would do and maybe better?.

ZMEnow · 09-19-2015, 09:04 AM

Quote:

Originally Posted by Emvici

I was reading a post this morning from someone that was experiencing an oil leak due to excessive pressure in the block. They had mentioned they replaced the oem oil cap with a breathable one. This sounds like a great idea, but I wanted to run it past who ever might be knowledgeable out there on the concept. Is it a good idea?, Can it throw anything off, with the compression or in the combustion chamber?. If it is a good idea, can anyone recommend one?. and Lastly how much can I expect to pay for a relatively good one? thanks to all, happy trails.

Using a Metco from Jannetty, he puts a quick release valve in them, and then resells..

FunkedOut · 09-19-2015, 03:30 PM

the catch can simply condenses and collects oil vapor on its way from the crankcase to the intake (along the PCV system)

the breather cap with check valve should work well without allowing additional air (unmetered) into the intake.

eta:
not sure if the ECU cares whether the cylinder load goes out the breather cap as blow by or if it goes out the exhaust.
probably the worst thing is for it to go back into the intake.

jayno20 · 09-19-2015, 10:29 PM

Quote:

Originally Posted by ZMEnow

Using a Metco from Jannetty, he puts a quick release valve in them, and then resells..

This.

Best release valve I've seen as well... Opens very easily and seals shut tight to not let unmetered air in.

Emvici · 09-20-2015, 09:29 PM

so the answer was the Catch can does not release the pressure that builds up in the block?. what is a metco?

thanks

Redlineviper · 09-21-2015, 07:06 AM

The catch can is just a pit stop the air and oil vapor make. The oil hops out and the air continues to their original destination at the front of the intake.

You can set up your system like I did and have a catch can with a breather but then need to cap off the where the lines fed the intake and may need to tune for the changes. The draw back to this is you will often smell some of the oil vapors that have a very easy way out through the ZL1 hood and into your car.

I rerouted mine to the lower fender area and that resolved that issue.

jayno20 · 09-21-2015, 12:17 PM

Quote:

Originally Posted by Emvici

so the answer was the Catch can does not release the pressure that builds up in the block?. what is a metco?

thanks

http://www.jreperformanceparts.com/2...-breather.html

Best breather I have used. It's pricey, but seems to be worth it.

RankSS · 09-21-2015, 12:36 PM

^^^ plus 1^^^

winterboy8 · 09-21-2015, 01:19 PM

What about installation, will it fit the stock oil fill cap opening or do you need to install it into the valve cover somewhere?

jayno20 · 09-21-2015, 01:28 PM

Quote:

Originally Posted by winterboy8

What about installation, will it fit the stock oil fill cap opening or do you need to install it into the valve cover somewhere?

It fits the stock opening. The engine cover will need to be modified if you are keeping it on.

Emvici · 09-21-2015, 05:41 PM

gee 110.00 for a glorified oil cap, I wonder if the benefits justify the price?. what exactly are the benefits of this breathable cap?.

RankSS · 09-21-2015, 07:24 PM

Quote:

Originally Posted by Emvici

gee 110.00 for a glorified oil cap, I wonder if the benefits justify the price?. what exactly are the benefits of this breathable cap?.

It only breathes when there is excessive crankcase pressure. A one way valve ensures no unmetered air get into the system.
I am not even sure if mine has ever even had to breath but it is cheap insurance against blown seals etc. for us FI people.

09-19-2015, 07:52 AM	#1
Emvici Drives: 2014 ZL1 White Convertible Join Date: Aug 2013 Location: St Pete Fl Posts: 682	oil breather cap I was reading a post this morning from someone that was experiencing an oil leak due to excessive pressure in the block. They had mentioned they replaced the oem oil cap with a breathable one. This sounds like a great idea, but I wanted to run it past who ever might be knowledgeable out there on the concept. Is it a good idea?, Can it throw anything off, with the compression or in the combustion chamber?. If it is a good idea, can anyone recommend one?. and Lastly how much can I expect to pay for a relatively good one? thanks to all, happy trails.

09-19-2015, 08:23 AM	#2
FunkedOut Drives: Black 2010 SS Join Date: Dec 2012 Location: FL Posts: 447 View My Garage	pressure in the crankcase is a result of blow by. the blow by is a result of combustion. combustion is a result of spark, fuel and *metered* air. that means the ECU knows how much air entered the engine. the PCV system should route the crankcase pressure back into the intake. if the breather cap allows it to escape to the atmosphere, the ECU thinks there's more air in the engine than there really is, and will command too much fuel, making you run rich. eta: actually, the blowby enters the intake post meter, displacing volume that would've otherwise been filled with fresh metered air. the blowby is generally void of O2 so fuel calcs are good. a breather cap eliminates this, but also allows unmetered air to enter the intake via the PCV system, altering fuel mixtures. if this happens in closed loop, the narrowband O2 sensors may be able to compensate, depending on the amount of air leaving the breather cap and the amount of trims left in the ECU. most likely, excessive blow by happens at WOT, where the engine runs in open loop, and the commanded afr is rich. only way to know how much is to measure with a wideband O2 sensor. Last edited by FunkedOut; 09-19-2015 at 04:41 PM. Reason: correction

09-19-2015, 03:30 PM	#5
FunkedOut Drives: Black 2010 SS Join Date: Dec 2012 Location: FL Posts: 447 View My Garage	the catch can simply condenses and collects oil vapor on its way from the crankcase to the intake (along the PCV system) the breather cap with check valve should work well without allowing additional air (unmetered) into the intake. eta: not sure if the ECU cares whether the cylinder load goes out the breather cap as blow by or if it goes out the exhaust. probably the worst thing is for it to go back into the intake. Last edited by FunkedOut; 09-19-2015 at 04:00 PM.

09-21-2015, 07:06 AM	#8
Redlineviper Drives: 2013 ZL1 Join Date: Jan 2015 Location: Orlando Posts: 936	The catch can is just a pit stop the air and oil vapor make. The oil hops out and the air continues to their original destination at the front of the intake. You can set up your system like I did and have a catch can with a breather but then need to cap off the where the lines fed the intake and may need to tune for the changes. The draw back to this is you will often smell some of the oil vapors that have a very easy way out through the ZL1 hood and into your car. I rerouted mine to the lower fender area and that resolved that issue. __________________ 2013 A6 ZL1

09-21-2015, 12:36 PM	#10
RankSS Drives: 2010 Camaro SS Join Date: Oct 2013 Location: Saskatoon SK Can. Eh Posts: 365	^^^ plus 1^^^ __________________ 2010 Camaro SS RS, Maggie with 3.4" pulley, 60# injectors, ADM dual fuel pumps, ADM Stage 2 Cam with Brian Tooley springs and pushrods, black CAI intake, Stainless Works long tube headers w/gutted cats, ZL1 Diff w/offset bushings, Pfadt lowering springs, Pfadt sway bars, Pfadt solid sub frame mounts, BMR trailing arms and toe rods, Hurst short throw shifter, Painted on Hugger Orange stripes, Forgestar F14 Piano Black wheels, Nitto NT05 rubber.

09-19-2015, 08:28 AM	#3
Emvici Drives: 2014 ZL1 White Convertible Join Date: Aug 2013 Location: St Pete Fl Posts: 682	I am using an Apex oil catch can, because when you started talking about the combustion blow-by it made me think of the catch can. Does this catch can essential do what the breathable cap would do and maybe better?.

09-20-2015, 09:29 PM	#7
Emvici Drives: 2014 ZL1 White Convertible Join Date: Aug 2013 Location: St Pete Fl Posts: 682	so the answer was the Catch can does not release the pressure that builds up in the block?. what is a metco? thanks

09-21-2015, 01:19 PM	#11
winterboy8 Drives: 2015 ZL1 Blue Velvet Metallic Join Date: Mar 2015 Location: Melbourne, FL Posts: 720 View My Garage	What about installation, will it fit the stock oil fill cap opening or do you need to install it into the valve cover somewhere? __________________ Roto-Fab CAI, ARH LT, SW 3" catback, JRE tune, Elite-2 CC, VMAX TB, Big Gulp, WW II relo, Lingenfelter S/C reservoir

09-21-2015, 05:41 PM	#13
Emvici Drives: 2014 ZL1 White Convertible Join Date: Aug 2013 Location: St Pete Fl Posts: 682	gee 110.00 for a glorified oil cap, I wonder if the benefits justify the price?. what exactly are the benefits of this breathable cap?.