997.2 Vacuum Level at Oil Filler Neck (let's build a data resource)
A while back I replaced the AOS on my 997.2 3.6l. (DIY link here https://rennlist.com/forums/997-foru...rator-diy.html )
The car was running great and consuming an average amount of oil according to Porsche guidelines, so this was purely a preventative step. Although the car ran great before, it does actually feel a bit better/smoother after the AOS install (particularly at idle and in the lower rev range) After researching the subject I realized there is really no reliable data online regarding what typical/expected vacuum levels should be on the 997.2. I bought the Porsche service manual and can't find it there, and even our helpful experts at Renntech are struggling to find the data. It seems this value can be useful in diagnosing a faulty (or near faulty) AOS if exceptionally high vacuum exists, or possible poor ring sealing if very low vacuum exists. This could be better confirmed by the real experts. However I thought it could help us all if we had a reference source where members could post their readings. I bought the following Manometer from Amazon, and checked it against a water tube manometer for accuracy before starting. https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 I bought a new filler cap for my car and used the old one to rig up the following using a brass fitting and plumbers tape to ensure it was air-tight: https://cimg6.ibsrv.net/gimg/rennlis...e07889b788.jpg https://cimg0.ibsrv.net/gimg/rennlis...64c58bfa41.jpg https://cimg1.ibsrv.net/gimg/rennlis...ccb27f2245.jpg 09 997.2 C2 (72k miles) car fully warmed up / engine oil around 180 to 190 deg F Reading Before AOS replacement = 13.9 in. H2O Reading After AOS replacement = 17.5 in. H2O https://cimg2.ibsrv.net/gimg/rennlis...0923b3838.jpeg https://cimg3.ibsrv.net/gimg/rennlis...a65a85c39.jpeg The reason I found this interesting is that most advice regarding older variants of 911 (996 and 997.1 in particular) suggest you should be seeing about 5 in. H2O. So I went ahead and measured my Panamera GTS and Cayenne S for comparison (with full understanding that they are very different engines, but figuring it would be an interesting comparison nonetheless). The Panamera had 36in. H2O !!! The Cayenne had 8in. H2O. Both of the above cars also run beautifully with no oil consumption issues at all. Please post your results here on your 997.2 values so we can build a reference for all who may be trying to diagnose issues, as the AOS subject comes up quite frequently. thanks in advance |
2009 C2S 102.5K miles, MT, original AOS
Oil usage: Approx. 1 qt Mobil 1 0w-40 in 5K miles at 100K miles Cold start: 18.8 After rev drop 14.3 (after about 1 mnt from cold start) At full operating temp, 180 oil (full, top line), 13.1 To remove oil cap for my 2009: 1: Open and pull out spout 2: “close” oil cap (flip up like closed with spout out) 3: Gently pry, with thin screwdriver, at clip, do not force 4: Tube will not fall into engine, just push is back in and install new cap The cap hinge pin has flattened sides that allow for easy removal from clips. Close the cap and the flattened sides align with clips and very easily comes off Peace Bruce in Philly |
While I applaud your efforts, the reason that there is not a data resource on 997.2 cars is because the AOS has not proven to be a problem on the 9A1 engines as it was on the M96/97 engines.
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You have pm
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Originally Posted by phaphaphooey
(Post 13663215)
While I applaud your efforts, the reason that there is not a data resource on 997.2 cars is because the AOS has not proven to be a problem on the 9A1 engines as it was on the M96/97 engines.
The reality is that the diaphragm is something that will fail eventually even with the revised design. There are also quite a few 997.2 owners with concerns about high oil consumption, and the AOS is one of those parts that can be a contributing factor. The aim therefore, is to preemptively build a data resource for when these AOS failures do become more common as more cars get up in both mileage and age. As mentioned, even the RennTech team could not find the recommended figure and the Porsche technicians Servive manual I purchased doesn't have it either. Interestingly there are examples of other engines/manufacturers which list the pressure values clearly such as in the example below. (see top of pg 22) http://www.natef.org/NATEF/media/NAT...-6-FSI-SSP.pdf VW 3.6l FSI engine
Originally Posted by Dan GSR
(Post 13663395)
You have pm
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On my car (09 C2 3.6L) with 74k miles, I got a reading of 13.6-13.7 at normal operating temperature.
Thanks Rob |
Thanks Bruce and Rob for posting your numbers.
I'm starting to wonder if the updated AOS I installed (p/n 9A1 107 040 02) uses a different membrane or spring to sustain a higher vacuum. Note there were 2 prior versions of this part available ending in 00 and 01. Is there anyone out there that has the new part and could share their measurements? |
2009 C2 3.6
33,070 miles 16.1 inches of water 2011 C4S 3.8 52,142 miles 12.9 inches of water both measured fully warmed up |
2011 997.2 C2 3.6
Mileage: 16,007 I had oil (Mobile One 0W40) and oil filter kit changed 3 months ago. COLD START: measurement started with 16.6 in. H2O then climbed to almost 19 in. H2O and started to drop again. AFTER REV DROP (about a min from cold start): 13.5 in. H2O FULLY WARMED UP: 11 in. H2O Many thanks to "Bruce In Philly" for providing instructions to remove the cap. I used a flat screwdriver wrapped with electrical tape to remove the cap and used my thumbs to clip it back after the measurements. Just make sure to keep the cap in "closed" position while uncliping it and cliping it back. https://cimg4.ibsrv.net/gimg/rennlis...63a510ad43.jpg https://cimg9.ibsrv.net/gimg/rennlis...e9478d00a3.jpg https://cimg9.ibsrv.net/gimg/rennlis...9d882ee6a4.jpg https://cimg5.ibsrv.net/gimg/rennlis...737da428da.jpg https://cimg9.ibsrv.net/gimg/rennlis...dfaa83d25e.jpg https://cimg5.ibsrv.net/gimg/rennlis...079a4c0cb5.jpg https://cimg0.ibsrv.net/gimg/rennlis...20e3d5db96.jpg |
Thanks for posting your results EC.
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Originally Posted by EMC2
(Post 13720871)
Thanks for posting your results EC.
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Not much consistency in numbers
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Updated original post to include link to AOS DIY.
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2009 C4S - 72k miles - burns approximately 1qt of oil every 800 miles (confirmed minor bore scoring). Measurements done at 725’ above sea level. 20.5” H2O directly after cranking while engine has high RPM. 16.7” H2O 60 seconds or so after cranking when RPMs drop to idle. 14.5” H2O after a drive with engine oil around 190 F. |
I found this in another thread and felt it was worth placing here.
Originally Posted by Flat6 Innovations
(Post 13254808)
....the other test that can be performed to test both ring seal, and the AOS is a manometer test. The DFI engine should test at 16" of water column, and can be slightly higher at sea level, and slightly lower at low elevations.
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