ive seen breathers replacing the oil cap on cars and ive seen breathers that looked liek they were going into the UIM, so im still not exactly sure whats its for, why would you want air in the oil? and how would oil not clog the breather? and what woudl be the poitn of a breather to the UIM if all the air is goign there anyway?

A vavle cover breather replaces the PCV on cars that have a modifacation the disables it, Such as a turbo.

A PCV is needed because some of the combustion energy bypasses the piston and goes down into the crankcase. This air has to go somewhere and the PCV lets it into the UIM.

To sum up your question, Breathers do nothing for our cars. Some folks like the looks of having one. And it does kinda give it that "Old School" look. But that'* about it. Purely cosmetic.

My car has a smoother idle, regardless of a new PCV. The idle changes noticeably when I remove the breather and re-install the cap, and with the breather, it seems to be slightly better revving.

But otherwise, with a proper working PCV, it'* not SUPPOSED to make a difference.

Why did I know Will would jump in and contradict me... :?

Don't get me wrong, I'm not saying there'* really any benefit to it. If I put my cap back on, it takes about 5 minutes for the PCM to re-adapt for idle. And the other way around, too.

SOMETHING is different.

Bill: Can you test the effects of breather effects by temporarily pulling the oil cap [of course not driving the car like that]?

-justin

Not necessarily. The cap is somewhat restrictive. And I don't really care that much to bother. My cap only breathes through a hole about the same ID as the PCV. Most are like that.

Okay.. because I had some free-revving issues, and I noticed my PCV Valve was a little loose. Oh well, a whole list of things could have been wrong, but I think we all know what step one is


-justin

Step 1: Do it again, asking for advice and help to ensure you do it right and don't have to take it apart again.

We are here to help out. Please, ask the questions.