Why install an oil catch can?

davenew · 06-21-2006, 03:06 PM

We can debate the effects of oil entering the engine all day long. It "allegedly" decreases efficiency of the ICs, causes carbon buildup in the engine, and can also contribute to knocking. I'm not sure what it does to sensors like the air temp sensor behind the throttle body.

All I can say for sure is.. No oil in my Y-pipe!! This area normally had a nasty oil buildup every time I pulled the valve out. This is after running the catch can for a few days. The past few days of driving included fats pulls, etc. I ran it extra hard today just to be sure I tested the can at max airflow.

In my opinion, if you have oil buildup here, you need a can. IF not, then you probably don't. I'll drain the can after two weeks and see how much it's catching. I don't expect much more than a teaspoon of oil, but you never know. I also plan on flushing the ICs, especially the driver side.

BTW, I have no idea how much residual oil enters the intake manifold thru the F-hose (or relocated pvc port at rear of manifold for >'00 models).

jazz215 · 06-21-2006, 03:34 PM

or a tampon for the y pipe

Mike2kS4 · 06-21-2006, 03:41 PM

Otherwise, your blowby gases will have nowhere to go but condense in the crankcase, and oil contamination will increase.

I'm this-way that-way on replacing the pcv valves. I'd probably clean and keep the OE variable-rate valves, since they're optimized for our blowby rates throughout the RPM range.

06-21-2006, 03:46 PM

davenew · 06-21-2006, 04:00 PM

I agree 100% on the factory limiting valve. The main reason I bought the new spider hose was for the valve. Mine got pushed against the coolant reservoir and cracked. The old spider hose was old and more brittle, but I couldn't find any cracks in the hoses.

Are you saying the catch can might be too restrictive? I guess I'll know if I drain it and nothing comes out. That would show there wasn't enough airflow in the pvc hose to pull oil into the can. It was pulling it before so it should pull the same amount into the can, right?

Mike2kS4 · 06-21-2006, 04:13 PM

Did you retain the manifold vacuum line on the spider? That's the important one. The one on the Y is to provide a purge during boost conditions... also important.

If you did these two things, I don't see a problem.

06-21-2006, 03:06 PM	#1
davenew AudiWorld Super User Account #: 70028 Join Date: Feb 2004 Posts: 7,828	Why install an oil catch can? We can debate the effects of oil entering the engine all day long. It "allegedly" decreases efficiency of the ICs, causes carbon buildup in the engine, and can also contribute to knocking. I'm not sure what it does to sensors like the air temp sensor behind the throttle body. All I can say for sure is.. No oil in my Y-pipe!! This area normally had a nasty oil buildup every time I pulled the valve out. This is after running the catch can for a few days. The past few days of driving included fats pulls, etc. I ran it extra hard today just to be sure I tested the can at max airflow. In my opinion, if you have oil buildup here, you need a can. IF not, then you probably don't. I'll drain the can after two weeks and see how much it's catching. I don't expect much more than a teaspoon of oil, but you never know. I also plan on flushing the ICs, especially the driver side. BTW, I have no idea how much residual oil enters the intake manifold thru the F-hose (or relocated pvc port at rear of manifold for >'00 models). __________________ '00 S4 EPL Stg 3 (March'04-May'08) '08 BMW 135i Dinan Stg 2 (May'08-Present) '00 S4 Imola widebody AWE Stg 3 (Bought Nov'08. AWE stg 3 kit is sold.. I'm switching over to ASP GT soon)

06-21-2006, 03:34 PM	#2
jazz215 Junior Member Account #: 83410 Join Date: Nov 2004 Posts: 676	wow, i definitely need one. or a tampon for the y pipe __________________ Jose@eurotech saved my motor! hooray WMS Cared, ASP Stg 3

06-21-2006, 03:41 PM	#3
Mike2kS4 Elder Member Account #: 38083 Join Date: Jun 2002 Posts: 12,105	Looks good to me, Just make sure you have vacuum in the system. Otherwise, your blowby gases will have nowhere to go but condense in the crankcase, and oil contamination will increase. I'm this-way that-way on replacing the pcv valves. I'd probably clean and keep the OE variable-rate valves, since they're optimized for our blowby rates throughout the RPM range. __________________ 2002 S4 Avant, 6spd. Bone stock. <a href="http://www.autospeed.us"> </a> Caveat: Any advice I express regarding potential tuning and such is purely informational. If your knowledge and abilities are not up to the task, no amount of advice can assist.

06-21-2006, 03:46 PM	#4
NO.BRAZIL::WTF Guest Account #: Posts: n/a	Red X

06-21-2006, 04:00 PM	#5
davenew AudiWorld Super User Account #: 70028 Join Date: Feb 2004 Posts: 7,828	I basically spent $100+ just to retain the stock valve.. I agree 100% on the factory limiting valve. The main reason I bought the new spider hose was for the valve. Mine got pushed against the coolant reservoir and cracked. The old spider hose was old and more brittle, but I couldn't find any cracks in the hoses. Are you saying the catch can might be too restrictive? I guess I'll know if I drain it and nothing comes out. That would show there wasn't enough airflow in the pvc hose to pull oil into the can. It was pulling it before so it should pull the same amount into the can, right? __________________ '00 S4 EPL Stg 3 (March'04-May'08) '08 BMW 135i Dinan Stg 2 (May'08-Present) '00 S4 Imola widebody AWE Stg 3 (Bought Nov'08. AWE stg 3 kit is sold.. I'm switching over to ASP GT soon)

06-21-2006, 04:13 PM	#6
Mike2kS4 Elder Member Account #: 38083 Join Date: Jun 2002 Posts: 12,105	Cool... Did you retain the manifold vacuum line on the spider? That's the important one. The one on the Y is to provide a purge during boost conditions... also important. If you did these two things, I don't see a problem. __________________ 2002 S4 Avant, 6spd. Bone stock. <a href="http://www.autospeed.us"> </a> Caveat: Any advice I express regarding potential tuning and such is purely informational. If your knowledge and abilities are not up to the task, no amount of advice can assist.

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