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Gelbster · 10-04-2017, 09:13 AM

Yes, 5" of water Vacuum is the maximum BUT-
I just fitted a new AOS and it shows 4.6" but has huge clouds of oil smoke !
Diagnosis:
I suspected the old AOS was due for replacement based on age and some white smoke after start up. The old AOS tested O.K. but replaced it anyway. The new one seemed no different in terms of white oil smoke production.
I dissected the old AOS to see if the diaphragm was sagging/torn. It was perfect .I epoxy-ed it back together to carry as an emergency spare.
Now I have huge plumes of white oil smoke and 4.6" of water vacuum on the Pyle manometer.
BTW the oil pressure at start-up is 75+ lbs on a newly rebuilt engine and the compression/leakdown is perfect and even on all 6 cyl
So is the 4.6" AOS defective/marginal ? What should a new, perfect AOS measure? Pelican say 4-7" and above 9" is a fail. They have an excellent DIY here:
"If you're still not sure, you can take a closer look at the hose that connects the air-oil separator to the intake manifold (yellow arrow, Figure 2). If the unit is failing, then there will be a significant amount of oil or residue in this tube. If the car is running rough, then removing this tube and blocking off both ends should disable the system and restore previous performance. This is not a long-term fix, but instead a short-term diagnosis step to use before you replace the air-oil separator."
http://www.pelicanparts.com/techarticles/Boxster_Tech/09-ENGINE-Air_Oil_Separator/09-ENGINE-Air_Oil_Separator.htm
http://cdn4.pelicanparts.com/techarticles/Boxster_Tech/09-ENGINE-Air_Oil_Separator/images_small/Pic2.jpg
I ask because there has been discussion of defective,new AOS units from even reputable suppliers. I bought my new (4.6") one from name begins with Auto and ends AZ******************************** Az., hmmmmm.

10-04-2017, 09:13 AM	#11
Gelbster Registered User Join Date: May 2014 Location: S.California Posts: 2,027	Yes, 5" of water Vacuum is the maximum BUT- I just fitted a new AOS and it shows 4.6" but has huge clouds of oil smoke ! Diagnosis: I suspected the old AOS was due for replacement based on age and some white smoke after start up. The old AOS tested O.K. but replaced it anyway. The new one seemed no different in terms of white oil smoke production. I dissected the old AOS to see if the diaphragm was sagging/torn. It was perfect .I epoxy-ed it back together to carry as an emergency spare. Now I have huge plumes of white oil smoke and 4.6" of water vacuum on the Pyle manometer. BTW the oil pressure at start-up is 75+ lbs on a newly rebuilt engine and the compression/leakdown is perfect and even on all 6 cyl So is the 4.6" AOS defective/marginal ? What should a new, perfect AOS measure? Pelican say 4-7" and above 9" is a fail. They have an excellent DIY here: "If you're still not sure, you can take a closer look at the hose that connects the air-oil separator to the intake manifold (yellow arrow, Figure 2). If the unit is failing, then there will be a significant amount of oil or residue in this tube. If the car is running rough, then removing this tube and blocking off both ends should disable the system and restore previous performance. This is not a long-term fix, but instead a short-term diagnosis step to use before you replace the air-oil separator." http://www.pelicanparts.com/techarticles/Boxster_Tech/09-ENGINE-Air_Oil_Separator/09-ENGINE-Air_Oil_Separator.htm http://cdn4.pelicanparts.com/techarticles/Boxster_Tech/09-ENGINE-Air_Oil_Separator/images_small/Pic2.jpg I ask because there has been discussion of defective,new AOS units from even reputable suppliers. I bought my new (4.6") one from name begins with Auto and ends AZ******************************** Az., hmmmmm. Last edited by Gelbster; 10-04-2017 at 09:44 AM.