Help Interpreting Manometer test (12 inH2O)

Hi all, I have a 2004 C4S that I posted about in another thread. Its been running fantastic, and still is, however, I did start noticing some oil loss recently. Not a lot, and within the factory spec but for the first 3k miles I put on it it consumed ZERO oil so this was odd to me. No smoke or anything or sooty tailpipes. Engine sounds fantastic no weird ticking, very smooth. I had the engine removed and a ton of things replaced when I first got the car - including AOS Did manometer test today with vacuum line hooked up to (-) terminal of the manometer and pulled a 12! My guess is I am a victim of the early AOS failure lottery but wanted to check in with the community to see if there was anything else that could be causing this like a vacuum leak? I'd like to put on the UAOS but don't want to just throw parts at it. Appreciate the help!!

With a -12 inh2o, you for sure have an early AOS failure. Nothing else will cause a high negative vacuum in the crankcase. Yours is the third or fourth case I have heard of in the last week or so of a "New Factory AOS failing" in short order. I suppose you still have a Warranty on it ?? Get a refund ..... You Tube UAOS is also now available at LN Engineering

Excellent! Thank you for confirming. Yeah, I bought it from FCP so it will for sure go back. This is the exact video I referenced to run the test - very useful test and very easy. I guess it will go into hiding until UAOS goes in.

UAOS is the way to go so you never have to worry about it again. Did you do the replacement yourself? I had much higher vacuum on mine, -30+ and as high as -60 and the car ran perfectly, although drank oil like a 1st year college student.

No, I had a shop do it and I used genuine Porsche part. The engine was out and it seemed like a good item to check off but perhaps monitoring inH20 w/ manometer and waiting for these to fail before replacement with UAOS is the best COA nowadays vs gratuitous preventative replacement.

I am one of the new AOS failures that Skip mentioned. I only have 300 miles since rebuilding my engine (including a new AOS) and started seeing smoke. Tested vacuum and was getting 19. I just purchased the UAOS AL from Skip and will be installing that. I really wish I would have done that last fall when I was assembling my engine rather than doing it now with the engine in the car, but... what's the odd's of a new AOS failing? I guess from what I'm hearing, it's not that usual but certainly not unheard of. I would follow Skip's advice (Porschetech 3) but I don't think you will find anyone suggesting to just monitor it. Your AOS is bad and it's not worth risking the potential to hydrolock your engine. In my opinion, you should bite the bullet and just have a UAOS installed now.

Yes, you and Dan and a couple of others have confirmed recently that their NEW Factory AOS has failed at very low time, less than 1 year, were probably bad out of the box. AOS failures have been so common that people who know these engines have been advising to replace the AOS every three years. But the problem has been way overshadowed by the IMSB issue. I emphatically DO NOT recommend driving a car with a failing or questionable AOS. Watch this video to see why.. You Tube

Quotes source post: 17433516

Yup. Car is sitting until the UAOS shows up and gets installed. Really glad I decided to do this test after noticing oil consumption change.

Skip, Are there enough miles on installed UAOS to know if the failure rate of the diaphragm is the same or better than factory parts? Isn't the diaphragm you supply the same material as the factory part? I guess my real question is wouldn't the same quality issues that plague factory parts affect your parts as well?

Unfortunately because of COVID I’ve put about 4000 miles on my 996.2 since I installed my UAOS. If not for COVID I’d have closer to 15,000 miles. The diaphragm is a factory VW/Audi part. I’d expect it to be at least as reliable as the Porsche AOS, which is not really saying much. I’m sure there is data for the VW/Audi part. It does not fit the FSI engine, but the diaphragm sure looks similar to the VW PCV diaphragm. The VW TSI engine diaphragm is NOT known for being reliable either. But the UAOS alerts you to a diaphragm failure and the accumulator captures oil to help prevent hydrolocking and possibly destroying the engine. Also it just takes 2 minutes to replace the UAOS diaphragm versus 4-6 hours for the Porsche AOS. Reliability of the diaphragm is of MUCH less concern with the UAOS. It is a MAJOR concern for the Porsche AOS.

Quotes source post: 17436450

I get why you�re asking but my opinion is... Really, it doesn�t matter. You can service it in 15 min and cheap enough to keep a spare on hand.

Quotes source post: 17436543

...add to that, if it does fail, the reservoir collects the excess oil that would hydrolock the engine and alerts you with a warning light.

The warning light works... I've seen it... ya know... testing Point of all this... there is NO GOOD REASON TO NOT put a UAOS on if ... 1. Stock one on the car is junk and needs to be replaced 2. You have the motor out 3. You plan on taking your car to the track

I have a UAOS sitting in my house. I will install this week it while my drivetrain is out waiting for the tranny repair. So yes, I agree with everyone, but still wonder why such a basic part fails so often. Could the vacuum in the system actually be higher than rated so the diaphragm comes apart from fatigue after a while? Or perhaps it is heat related being stuck in the back of the motor (for the OEM design)? The Indy who removed my engine is an Audi specialist and tuner (as well as a long time P-car specialist). He told me newer Audis and VWs are having similar failures, especially in really cold weather when the AOS freezes up and causes catastrophic engine damage. You'd think VW Auto Group would've figured this out by now.

Quotes source post: 17434333

I think the amount of labor required, whether DIY or shop, is enough of a reason to go UAOS. Can you share what the oil consumption looked like? I think it would be an interesting data point to collect. i.e. - I had a failed reading of X and noticed oil consumption of Y in 1000 miles or so. Furthermore, and I know Skip is a data junkie, It would be cool to see what everyone's failed readings looked like, after UAOS install (feel free to include your location / elevation) and any other symptoms, like oil consumption or noises.

I can't watch the video from work, what should the manometer read for a good AOS? Can someone post a link to a manometer?

Quotes source post: 17437885

Stock AOS: 4-7inh2o UAOS: runs just under 4 to 7. Mine is under 4, but I live at 35' above sea level.

@sasilverbullet , my Manometer looks like this one: Amazon Amazon You just need an adapter for the oil cap. They're easy to make. Let me know if you need any fittings. I still have a bunch from when I was makings these and selling them.

Quotes source post: 17438007

Ok, just ordered the meter, do you have an old cap with a fitting to send me?

Quotes source post: 17438030

I'm out of pre-made ones. (I sold my last pre-made a week or so ago) But I think I have a few brand new caps and I have tons of fittings. I could make you one and have it mailed by the end of the week. PM me your address.

Quotes source post: 17436450

Hi Joel, The UAOS has been out for 17 months and no diaphragm ruptures to date. The diaphragm I use is substantially more robust than the OEM Porsche diaphragm Pictures below). The Facotry diaphragm is only .016 in thick all the way across the diaphragm. The UAOS diaphragm has a nylon support that is molded into it that is .200 thick and covers 90% of the surface, the remainder is 1/3rd thicker than Factory. I don't expect it to last forever but I do expect it to last longer than OEM Factory. I recommend replacement/service at 4 years. ( the UAOS diaphragm can be opened and replaced or cleaned/serviced) , but using the URO just makes since to replace it, and it is so easy to get to on the UAOS system. The UAOS pre-sealed AOS carries a "lifetime warranty" (since there is nothing to fail inside after mod) all other components carry a 2 year Unlimited Mileage Warranty.(same as Porsche OEM parts) I have evaluated/tested 8 different brands of the same diaphragm and can say that some are really low quality, I won't bore everyone with all the technical details that I could rattle on about, as I am in the sales marketing mode right now. Pics of a OEM Porsche Factory diaphragm, (blue) and a UAOS diaphragm, (red)..

Skip, Thank you for the explanation. So the UAOS kit with a URO 15629 has the red diaphragm?

Quotes source post: 17438007

That reminds me. And I had to pull it up again to refresh my memory (along with shock and disbelief). Pic appears to be the same exact manometer as a $42 one on Amazon. Or is a "crankcase AOS vacuum measurement tool" different? Of course you get the tubing and cap so I guess that's worth the extra $400? Oh, and that pad print is different. In the realm of overpriced bearings, oil, UOA, etc? I'd go with "yup!".

Quotes source post: 17439841

Yes, the red one is used on the UAOS system,( although your 15629 # doesn't cross reference) It is identical to the one used in the OEM VW/Audi units made in the Cech Republic . The blue one is from an OEM Porsche unit made by Mann+Hamell same company that make the Porsche Motorsport AOS.

Skip, Thank you - I know - a thousand questions *after* buying a UAOS (kind of like a post PPI - ha ha). Did URO just get lucky with their design or do you think they addressed a problem discovered with Audi/VW? Meanwhile, Porsche takes the lowest cost part, installs it in thousands of cars and then tells their customers to pound sand.

I'm surprised Porsche HQ hasn't contacted PorscheTech3 to arrange buying out this product for themselves. Seems like an ingenious product that would save lots of these engines, especially the ones that go to the track.

Quotes source post: 17440721

The URO brand (part of APA Industries) has a hit-n-miss type of reputation. Some parts are not well developed but others are above and beyond the Factory stuff and I think they "try" to improve parts as seen by there obvious upgraded URO Aluminum AOS connector vs the Factory plastic piece. This diaphragm/flow regulator was also backordered last year for a few months while they were doing an update to the design,( was mainly for the Audi cold weather sludge/icing issue) although I could not tell the before vs after difference, there was an update that took a couple months. The OEM Porsche AOS has been updated 5-6 times and is still junk..

Quotes source post: 17440837

What, and admit they made a mistake, never! Just like they didn't purchase the IMS Solution patent. We should all be grateful they didn't. The prices would have quadrupled.

Quotes source post: 17440961

Lol, I think you'd have to look to a Falcon9 rocket to find a bearing more expensive than the IMS Solution, or most of the others for that matter. As far as Porsche's AOS, don't forget about their "Performance version designed for track use" (at only $936!). I guess they realized their shelf unit DOES have some deficiencies when their cars are used as they advertise: https://www.pelicanparts.com/More_In...s=0&SVSVSI=900 If I tracked I'd surely go for Skip's UAOS, a brilliant design. For my typical "spirited" drive I'm good with the stock unit. I think for the average guy like me the chances of a hydro lock would be extremely rare, and that would be if I ignored the symptoms.

Quotes source post: 17440837

Well, if Porsche HQ ask's where to find me, be sure to tell them... and I'll just retire..."again"...

Most people have no idea how frequent AOS failure is or how sneaky the "Silent Killer" can be, it has been over-shadowed by other M96 issues (IMSB). It doesn't have to be a big rip that blows a ton of smoke and causes a CEL, rough running or any other symptom, it can happen slowly without notice on a mildly driven car., It has to do with the way the intake manifold is designed and shaped internally. There is a depression or cupped like shelf that runs alone each intake that can hold enough oil to lock the engine. It can accumulate very slowly over time and then dump as you turn into a steep driveway or sharp turn. This is actually how most of them die..Kind of like a red Solo cup sitting on top of the front door with a string tied to it that when it gets full of oil it dumps as you open the door.

[Image-only post; no author-written text. Original image references:] https://cimg1.ibsrv.net/gimg/rennlist.com-vbulletin/2000x1504/img_9792_d456a7adf7c36140c893454cef09bd66d9eb0b5b.jpeg

Quotes source post: 17437713

I replaced the AOS with brand new Porsche part in April of 2020. No oil consumption at all between then and beginning of 2021. Part failed at approx 2k miles if you back into that. The car used approximately 1qt of oil within the span of about 1000 mi. I live at roughly 200' ASL (San Diego). No other symptoms. My car is currently sitting under a cover until I receive the UAOS I ordered, not my daily driver anyway so no need to risk damage for no reason. I am also going to do the CPS and fuel injectors as well since the thing is going to have to all come apart again.