I have had the oil breather eye candy for a few years now and I have the original PCV system untouched.
I haven't noticed any problems and I must be running rich from the looks of my sooty tailpipe.

Yeah I've actually had mine since before the rebuild and it didn't seem to have caused problems then. The strange thing is if you look at my plugs it would seem I was running perfect if not a slight bit rich. The maxed out fuel trims told another story though. It had me hunting down PCM ground wires and debating a replacement till I figured out this was the source. I'd love to see someone else that uses one try looking at their o2 mv and fuel trims with and without one. My issue was obvious though, it affected my idle. Strange stuff I guess...

Could we see a pic? I'm not sure I know what you're talking about. I'm fairly interested, because last time I scanned my car I got some weird O2 readings. Probably not related, but I'd still like to see a visual.

Hmmm... okay, got another one for you: what'* it do? Lol, I understand a little bit from the previous posts, but do you have a quick Oil Breather 101 link or explanation? Thanks Jay.

Sure, I'd type it myself but I'm a little tired. Here'* a few choice paragraphs:

Other materials which collect in the crankcase, such as water, acids, and unburned fuel, may be in the form of either liquid or vapor. These materials are by-products of the combustion process. For example, when gasoline is burned in the presence of an adequate air supply, water is produced at a rate of about one gallon of water for each gallon of gasoline that is burned.

Most of the water and acids created as vapor in the combustion chamber are carried out of the engine through the exhaust. However, some of these vapors reach the crankcase as blow-by. This means that vapor is forced between the rings and the cylinder walls by combustion pressures which are as high as 700 lbs. per square inch. Blow-by occurs even with engines in good condition, but increases as engines become worn. Unburned fuel resulting from incomplete combustion may also enter the crankcase as blow-by vapor. Additionally, some unburned fuel may be forced into the crankcase on the compression stroke of the engine before the fuel/air mixture is ignited. Pressure in the combustion chamber during the compression stroke may be as high as 200 lbs./psi.

Positive Crankcase Ventilation (PCV) is a system that was developed to remove harmful vapor from the engine and to prevent vapor from reaching the atmosphere. The PCV system accomplishes this by using manifold vacuum to draw vapor from the crankcase into the intake manifold. Vapor is then carried with the fuel/air mixture into the combustion chambers where it is finally burned. Thus, PCV is effective as both a crankcase ventilation system and as a pollution control device.

OPEN PCV SYSTEMS
The open system draws fresh air through a vented oil filler cap. This presents no problem as long as the vapor volume is nominal. However, when the crankcase vapor becomes excessive it is forced back through the vented oil filler cap and into the open atmosphere. Therefore, the open PCV system though successful at removing contaminated vapors from the crankcase is not 100% effective as a pollution control device.

CLOSED PCV SYSTEMS
The closed PCV system draws fresh air from the air filter housing. The oil filler cap in this system is NOT vented. Consequently excess vapor will be carried back to the air filter housing where it enters the intake manifold through the carburetor. The closed system prevents vapor, whether normal or excessive, from reaching the open atmosphere. The closed system is very effective as an air pollution control device.

Blow-by gases and vapor should be removed at about the same rate they enter the crankcase. Since blow-by is nominal at idle and increases during high-speed operation the PCV valve must control the flow of vapor accordingly. The PCV valve is designed to compensate for the ventilation needs at varying engine speeds. It is operated by manifold vacuum, which increases or decreases as engine speeds change.

http://www.magnumproducts.com/faq.htm

I'm still seeing a oil cap breather has a leak that would cause high fuel trims. But this thread has started some moving of gears in my head so I'm gonna test out my old breather on my 98.

Maybe I'll pick one up and give it a go. What'* a good source for an appropriate breather cap?

So, what is the advantage to running an oil breather?

Jr's3800: in your '91, what changes do you notice, and the "stalling" you get when you pull it off, is that with the PCV system still intact?

If I wanted to eliminate the PCV system, could I just use this oil breather, and get rid of my Charcoal Canister while i'm at it?


-justin

There'* no benefit to removing the PCV valve. If you're gonna do only breathers, you'll probably want to do a new valve cover with the breather on the back.