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Old 08-01-2015, 03:55 PM   #1
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Cheap AOS

I keep reading about people changing a bad AOS and having it go bad again, a year or so later. Are there any upgrades available? I'd like to spend more and trust that it will last a while. I'm about to do mine as a preventive maintenance item and I'd like something good.

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Old 08-01-2015, 04:26 PM   #2
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Plumbing a Jeggs AOS in line into mine has worked. Not the solution for everyone...
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Old 08-01-2015, 07:10 PM   #3
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Was the Jegs unit a complete replacement or an add-on to the Porsche AOS
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Old 08-02-2015, 08:39 AM   #4
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AOS mods & upgrades

"Plumbing a Jegs AOS in line into mine has worked. "
This would be a great way of being able to check the volume of oil being passed by the AOS. Useful if you think it is beginning to fail.
If you want something more OEM looking ,perhaps one of these ?
Oil Catch Cans
But the critical part IMHO is -how ,exactly did you connect it? What fittings and where ? It looks/measures as if a 3/4" line would work.
We are not alone with this issue.The BMW guys have also fitted oil separators:
My CVV (Oil Separator) DIY Journey in Pictures - Bimmerfest - BMW Forums
Lots under "catch cans" on Fleabay. Need one with AN12 or 3/4 or 20mm fittings, perhaps 5/8"?
This might work/ The orientation of the fittings is convenient.
http://www.ebay.com/itm/SHR-Tru-Billet-Universal-Oil-Separator-Black-/221738029620?hash=item33a09dd234&vxp=mtr
http://www.silverhorseracing.com/shr-tru-billet-oil-separator-universal.html
http://www.stangmods.com/JLT-Oil-Separtor-p/01369.htm

Last edited by Gelbster; 08-06-2015 at 03:15 PM.
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Old 08-02-2015, 08:51 AM   #5
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Isn't there an opportunity for someone to make a better aftermarket unit? I wonder how much longer these will be available from Porsche.
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Old 08-02-2015, 09:09 AM   #6
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There is a theory that you can upgrade the diaphragm (the part that rips!) with a superior one scavenged from a BMW AOS.
It would be a great diy to replace the cheapo OEM diaphragm with a piece of Viton or similar/better?
http://www.amazon.com/Fluoroelastomer-Durometer-Smooth-Finish-Backing/dp/B00CCGYGEG
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Old 08-03-2015, 10:10 AM   #7
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Quote:
Originally Posted by thom4782 View Post
Was the Jegs unit a complete replacement or an add-on to the Porsche AOS
i can't speak for 'fro, but the aos vents three different locations - both heads and the case. that would mean a lot of hose re-routing and fabbing adaptors to replace the aos altogether. prolly the easier route would be to put the aftermarket aos between the stock unit and the intake as a backup.
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Old 08-03-2015, 11:31 AM   #8
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Someday I plan to flip my "T" plenum upside down to move the AOS connection to the drivers side where there's more room to install a catch can etc. inline.
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Old 08-03-2015, 12:27 PM   #9
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Quote:
Originally Posted by Gelbster View Post
There is a theory that you can upgrade the diaphragm (the part that rips!) with a superior one scavenged from a BMW AOS.
It would be a great diy to replace the cheapo OEM diaphragm with a piece of Viton or similar/better?
http://www.amazon.com/Fluoroelastomer-Durometer-Smooth-Finish-Backing/dp/B00CCGYGEG
I was thinking the same thing, although I have no experience with the BMW PCV system. It would be nice to have an AOS like the motorsport version, but with a replaceable diaphragm. Viton would be perfect as it is unaffected by oil and fuel.
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Old 08-03-2015, 12:59 PM   #10
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I was thinking the same thing, although I have no experience with the BMW PCV system. It would be nice to have an AOS like the motorsport version, but with a replaceable diaphragm. Viton would be perfect as it is unaffected by oil and fuel.
Brad Roberts claims to make something like this
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Old 08-06-2015, 09:09 AM   #11
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Quote:
Originally Posted by The Radium King View Post
i can't speak for 'fro, but the aos vents three different locations - both heads and the case. that would mean a lot of hose re-routing and fabbing adaptors to replace the aos altogether. prolly the easier route would be to put the aftermarket aos between the stock unit and the intake as a backup.
That's exactly what I've done. I cut the connector end off the old AOS to give me a good end, then tapped and threaded in a brass hose fitting. Did the same on the intake side (cutting into a perfectly good 75mmTB intake gave me the willies). I had to plumb in a smaller T into the AOS line to accomodate the fuel vent line.

When that bowl in the supplemental AOS gets about 1/4" of oil in it I will pour it back into the oil filler. When I'm AXing or driving hard, hardly any oil accumulates at all. When I'm poking along on the interstate/ steady state low throttle driving I'll drain it about every 360 miles or per fuel fill-up.
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Old 08-06-2015, 03:36 PM   #12
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Interesting progress here.
There seem to be 3 parts to the AOS upgrade issue?
1. substitute barbed brass pipe connectors into the stock plastic connections of the AOS - cut +epoxy.This allows easy connection of generic hose.
2. collect any oil condensate from a correctly functioning AOS in a small catch can -like the Jegs one linked previously.
This also serves as a catch for any larger volume of oil dumped when the AOS diaphragm begins to fail . Functions as a visual early warning system ?

3.The big challenge is to upgrade the material of the diaphragm to something that is unaffected by heat & oil fumes. Viton seems the obvious choice but I am guessing. Replacing the diaphragm would require careful slicing of an old AOS and then glue-ing in a Viton replacement. A 9" diam plain Viton diaphragm is $7 on EBay.I have no idea if it would work but is sure big enough for several attempts !!
http://www.ebay.com/itm/VITON-FLUOROELASTOMER-Disc-Rubber-Gasket-Material-9-inch-Disc-x-1-16-1-piece-/261556610601?hash=item3ce5fd2629

Last edited by Gelbster; 08-06-2015 at 03:41 PM.
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Old 08-08-2015, 11:36 AM   #13
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Quote:
Originally Posted by Gelbster View Post
Interesting progress here.
There seem to be 3 parts to the AOS upgrade issue?
1. substitute barbed brass pipe connectors into the stock plastic connections of the AOS - cut +epoxy.This allows easy connection of generic hose.
2. collect any oil condensate from a correctly functioning AOS in a small catch can -like the Jegs one linked previously.
This also serves as a catch for any larger volume of oil dumped when the AOS diaphragm begins to fail . Functions as a visual early warning system ?

3.The big challenge is to upgrade the material of the diaphragm to something that is unaffected by heat & oil fumes. Viton seems the obvious choice but I am guessing. Replacing the diaphragm would require careful slicing of an old AOS and then glue-ing in a Viton replacement. A 9" diam plain Viton diaphragm is $7 on EBay.I have no idea if it would work but is sure big enough for several attempts !!
Viton Fluoroelastomer Disc Rubber Gasket Material 9 inch Disc x 1 16" 1 Piece | eBay
I have wanted to do this but never get around to it, I'll send you my extra AOS if you are ready to experiment.
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Old 08-08-2015, 12:12 PM   #14
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Bill ,
I would be pleased to try this. My engine is still out of the car so the timing is perfect.And my engine already has one of your pistons ,so whay not an AOS also:-).
I am apprehensive/puzzled why others have not already tried this upgrade. The modifications are simple,inexpensive,require no special tools/skill .
The AOS problem has bedeviled the M96 community for a long time ,so can it be that only Brad Roberts has this solution?Perhaps he just substitutes a complete BMW system? see links below.

The BMW AOS/vent system may be more durable than the M96(??) but it still causes adverse comments on Beemer Forums.
I would try one but am confused about the quality. Some are $50,others $150:
BMW PCV Crankcase Vent Valve Oil Separator Breather Hose Kit Premium 566 | eBay
BMW PCV Oil Separator Crank Case Vent Valve Breather Hoses Kit Genuine | eBay

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