I installed a catch can on my '99 MN6 about seven months ago. I checked it every month and usually got about a tablespoon worth to drip out. I assumed that all was well and that not a lot of oil was flowing and fouling.

Well......I took my TB off to replace in and I stuck my hand into the mouth of the Fast intake. TONS of oil. All over the floor of the intake. I mean puddles. It was clearly coming from where the hose from the catch can connects into the intake.

What the heck is going on!? Anyone else had these issues??

 

Oh man, are you singing my song....

After finding it puking into my MAF at the track I did some investigation...I had puddles at the intake port on the heads, all through the system etc. AND I was running a can.

Apparently, this oil is so find it comes through the breather hose into the throttle body this way. My personal thought is it happens more on deceleration in the autos but I could be wrong about that. The solution I have seen is to put a second catch can on. I tried t-ing the two lines together and got the strangest whining noise you have ever heard...honestly, don't do that. Its scary how much it sounded like a front trans pump on its way out.

Anyway, best solution I have seen is two cans. Also seen ones baffled and vented to atmosphere rather than back into the intake, although this is for off road use only (! ).

Cassidy

 

You guys saying that just made me want a catch can and also be scared of them. Do you guys recommend a can for a basically stock car?

 

Which catch can are you guys running?

 

AMW baffled.

 

I have a stock A4 with the Elite Engineering catch Can. I'm collecting about 2 teaspoons every 2-3k.

 

I have two C5s, one with an Elite can that catches plenty and another with an offbrand that has never caught a drop. There's a new Elite setting behind me right now. Anybody want a hot deal on the offbrand?

 

I have an Elite can and drive my car very hard on the street. I get about 12-16 oz (1.5" in the can) last check at around 6K. If you are at higher rpms (say 3500 to redline shifting a lot like me, then it will pull quite a bit out)

 

I'm catching very little, I really did not have a problem but installed one just in case

 

I haven't run the additional tubing to include that line in my catch can yet, but my catch can is catching a lot of oil still. I think my oil ingestion is also causing knock retard at the track.

 

Yes, my engine is stock save for headers, and I get a good bit out of my EE can.

 

I get maybe a teaspoon per 1,000 miles from the ELITE ENGINEERING catch can on my car. I don't drive the car hard and it's only got 5,700 miles on it, so maybe that's got something to do with it.

 

I have one and it is a really nice piece, well worth what I paid. Unfortunately I just added it so I don't know how well it will work. I also switched over to an LS6 PCV setup to help with oil consumption. If I had to pick between the two the LS6 PCV setup will probably do more than a catch can. It will also help clean up the engine bay and is a bargain at about 65 bucks.

 

Keep in mind that most of the high-dollar catch cans are nothing more than stainless steel brillo-pad-like material in an aluminum can. Oiled piston compressors are somewhat similar to engines in that oil will get past the cylinder rings as "blowby". Industrial users of said compressors often have to trap this oil before it gets into and onto sentitive components or materials. To do so, both particulate and coalescing filters are used, depending upon the length of air line between the compressor and the sensitive parts.
Take a look at a coalescing filter element and compare it to the filter "mesh" in a typical catch can. You'll find that the borosilicate glass fiber element is far more dense than the course stainless steel mesh. The higher density pretty much guarantees that more of the airborn oil is trapped.

Can a coalescing filter trap ALL the oil from blowby? No, since almost every filter requires a certain amount air velocity and pressure to maximize its trapping ability. When we accelerate aggressively, vacuum pressure drops dramatically and at the same time, blowby oil volume increases. However, it is especially important to have as dense a filter as possible without impeding flow. This is why coalescing filters are better choices for trapping oil in automotive systems.

Disadvantages? The only disadvantage of using a low-cost coalescing filter is that you may not want to mount it to glowing hot headers or other super-hot engine parts. And you may have to replace its filter every few years, but overall, your intake should be better off.

For a more in depth article about trapping oil, see:

http://www.conceptualpolymer.com/PCV...oval%20101.pdf

Dave

 

Whats a catch can ?

Whats a filter ????




DH

 

Well not many will want to go to my extreme but here is what I have:

TWO catch can (one Elite and one AMW)
TWO Watts filte setups as DAVE suggests (one with the coalescing element and one with the hard stone like material that was in the old Home Depot cans)

The main line has the AMW followed by the Watts with coalescing elem.
The fresh air line has the EE followed by the Watts with stone element.

Both catch some oil depending on how I'm driving. The main line always has more.


DH

 

I've said it before and I'll say it again - Howie is THE catch can master!

 

what happens if you dont have a catch can?

 

Oil in your intake manifold will inevitably result in carbon buildup on the pistons and pinging under load due to higher compression. The ECU will then retard timing (as it does when the intake air gets very hot), resulting in a loss of power.

Catch cans are intended to be oil "traps" to prevent this from happening. However, as you read in the first post, they don't always do very well in that respect.

 

1 - The engine will work as designed.

2- normal wear and tear of your engine lets the engine build up more blow-by gasses that will make their way to your intake system.

Installing just about any catch can and servicing your PVC system more often will help reduce any problems.