08 987 AOS failure
11-25-2013, 11:31 AM
#1
08 987 AOS failure
An air/oil separator failed badly on my car last week. Vast clouds of whitish smoke. Oil contaminated the plugs, O2 sensors, air intake and exhaust, catalytic converter, and probably a few other things I don't recall. Parts and labor to repair? $10,500. Porsche has agreed to pay for half as a goodwill gesture.
There was no warning, no CEL, no noise or sudden change in power, no other indications at all except the huge smoke cloud pouring from the back of the car.
Car is at 68,000 with all maintenance done faithfully at the dealer I ordered it from. At least Porsche is assisting, and the dealer gave me very nice 2013 Cayenne Diesel as a loaner. I was scared to death the engine was blown, so even though that's a shocker of a repair bill, it wasn't as bad as I feared.
There was no warning, no CEL, no noise or sudden change in power, no other indications at all except the huge smoke cloud pouring from the back of the car.
Car is at 68,000 with all maintenance done faithfully at the dealer I ordered it from. At least Porsche is assisting, and the dealer gave me very nice 2013 Cayenne Diesel as a loaner. I was scared to death the engine was blown, so even though that's a shocker of a repair bill, it wasn't as bad as I feared.
11-25-2013, 08:40 PM
#4
Bart, I'm very sorry to hear that. 
Glad you're taking it in stride. 
I'm slightly puzzled, however, by the amount you were quoted and the number of things that needed replacing. FWIW, many, many people have had failed AOS and came nowhere even remotely close to the figure and the parts that you mentioned... Typically, it's just an AOS replacement ($500!!) +/- MAF sensor. MAF can be cleaned but AFAIK it's not very successful most of the time, i.e. need a new one (~$350-500).
I have no knowledge of your situation whatsoever and what may or may not have been involved, but could it be that they were going ultra-conservative and replacing anything and everything that could've possibly been affected by the ingested oil? Just sayin'................
Fred: AOS is the air-oil separator. The diaphragm can get torn over time and need replacing. Note that this is much more accelerated in tracked-hard 987.1 cars. AOS/VOS separates the air from oil and returns oil to the proper places where it belongs. A tear in the diaphragm will let the oil get sucked in and result in huge plumes of smoke in your wake, i.e. "crop dusting" - not to be confused with other reasons for why Porsches can smoke on start-up!
Many who track their 987.1s hard go with the Motorsport VOS, whether it's the 911 part that needs modifications to fit (PITA) or the 987 part ($$). No need to do so in street 987s, BTW.
Fred, since you have a 987.2 I'm happy to report that there's no need for you to worry about this as Porsche fixed most of the 987.1 shortcomings in 987.2s (believe me, I've owned both).
Just keep AOS in the back of your mind as a possible replacement item if your car starts smoking heavily (esp. on the track) in the future.
Glad you're taking it in stride. I'm slightly puzzled, however, by the amount you were quoted and the number of things that needed replacing. FWIW, many, many people have had failed AOS and came nowhere even remotely close to the figure and the parts that you mentioned... Typically, it's just an AOS replacement ($500!!) +/- MAF sensor. MAF can be cleaned but AFAIK it's not very successful most of the time, i.e. need a new one (~$350-500).
I have no knowledge of your situation whatsoever and what may or may not have been involved, but could it be that they were going ultra-conservative and replacing anything and everything that could've possibly been affected by the ingested oil? Just sayin'................
Fred: AOS is the air-oil separator. The diaphragm can get torn over time and need replacing. Note that this is much more accelerated in tracked-hard 987.1 cars. AOS/VOS separates the air from oil and returns oil to the proper places where it belongs. A tear in the diaphragm will let the oil get sucked in and result in huge plumes of smoke in your wake, i.e. "crop dusting" - not to be confused with other reasons for why Porsches can smoke on start-up!
Many who track their 987.1s hard go with the Motorsport VOS, whether it's the 911 part that needs modifications to fit (PITA) or the 987 part ($$). No need to do so in street 987s, BTW.Fred, since you have a 987.2 I'm happy to report that there's no need for you to worry about this as Porsche fixed most of the 987.1 shortcomings in 987.2s (believe me, I've owned both).
Just keep AOS in the back of your mind as a possible replacement item if your car starts smoking heavily (esp. on the track) in the future.
11-26-2013, 11:01 AM
#6
Bart, I'm very sorry to hear that. Glad you're taking it in stride.
I'm slightly puzzled, however, by the amount you were quoted and the number of things that needed replacing. FWIW, many, many people have had failed AOS and came nowhere even remotely close to the figure and the parts that you mentioned... Typically, it's just an AOS replacement ($500!!) +/- MAF sensor. MAF can be cleaned but AFAIK it's not very successful most of the time, i.e. need a new one (~$350-500).
I have no knowledge of your situation whatsoever and what may or may not have been involved, but could it be that they were going ultra-conservative and replacing anything and everything that could've possibly been affected by the ingested oil? Just sayin'................
Fred: AOS is the air-oil separator. The diaphragm can get torn over time and need replacing. Note that this is much more accelerated in tracked-hard 987.1 cars. AOS/VOS separates the air from oil and returns oil to the proper places where it belongs. A tear in the diaphragm will let the oil get sucked in and result in huge plumes of smoke in your wake, i.e. "crop dusting" - not to be confused with other reasons for why Porsches can smoke on start-up! Many who track their 987.1s hard go with the Motorsport VOS, whether it's the 911 part that needs modifications to fit (PITA) or the 987 part ($$). No need to do so in street 987s, BTW.
Fred, since you have a 987.2 I'm happy to report that there's no need for you to worry about this as Porsche fixed most of the 987.1 shortcomings in 987.2s (believe me, I've owned both). Just keep AOS in the back of your mind as a possible replacement item if your car starts smoking heavily (esp. on the track) in the future.
Glad you're taking it in stride. I'm slightly puzzled, however, by the amount you were quoted and the number of things that needed replacing. FWIW, many, many people have had failed AOS and came nowhere even remotely close to the figure and the parts that you mentioned... Typically, it's just an AOS replacement ($500!!) +/- MAF sensor. MAF can be cleaned but AFAIK it's not very successful most of the time, i.e. need a new one (~$350-500).
I have no knowledge of your situation whatsoever and what may or may not have been involved, but could it be that they were going ultra-conservative and replacing anything and everything that could've possibly been affected by the ingested oil? Just sayin'................
Fred: AOS is the air-oil separator. The diaphragm can get torn over time and need replacing. Note that this is much more accelerated in tracked-hard 987.1 cars. AOS/VOS separates the air from oil and returns oil to the proper places where it belongs. A tear in the diaphragm will let the oil get sucked in and result in huge plumes of smoke in your wake, i.e. "crop dusting" - not to be confused with other reasons for why Porsches can smoke on start-up!
Many who track their 987.1s hard go with the Motorsport VOS, whether it's the 911 part that needs modifications to fit (PITA) or the 987 part ($$). No need to do so in street 987s, BTW.Fred, since you have a 987.2 I'm happy to report that there's no need for you to worry about this as Porsche fixed most of the 987.1 shortcomings in 987.2s (believe me, I've owned both).
Just keep AOS in the back of your mind as a possible replacement item if your car starts smoking heavily (esp. on the track) in the future.The result was that compression was good and all within specs, but the oil damaged or ruined intake and emissions components, and even got into the exhaust. He said they aren't including replacing the muffler, but that it will likely smoke for a while as the oil burns away.
I have a really good service rep there, and I know one of the main Porsche mechanics as well. I actually trust them a bit lol. And the dealer will stand behind their work.
I know I could try to relocate the whole mess to an outside shop and maybe have the repairs done for less, but at what ultimate cost? The fact that I bought there and have all the maintenance done there (dealer is literally 2 blocks from my office) means they really know me and the car, and I always get a great loaner. Since Porsche is chipping in, it might not be that much less somewhere else, and I'd still need to rent a car for a couple of weeks.
So all in all it might have been a lot worse. I am very, very fond of this car.
I'm going to follow up with him after the holiday and ask a few more questions about what they speculate happened and how to prevent it.
I'll keep everyone posted.
11-26-2013, 12:56 PM
#7
I have a really good service rep there, and I know one of the main Porsche mechanics as well. I actually trust them a bit lol. And the dealer will stand behind their work.
I know I could try to relocate the whole mess to an outside shop and maybe have the repairs done for less, but at what ultimate cost? The fact that I bought there and have all the maintenance done there (dealer is literally 2 blocks from my office) means they really know me and the car, and I always get a great loaner. Since Porsche is chipping in, it might not be that much less somewhere else, and I'd still need to rent a car for a couple of weeks.
I know I could try to relocate the whole mess to an outside shop and maybe have the repairs done for less, but at what ultimate cost? The fact that I bought there and have all the maintenance done there (dealer is literally 2 blocks from my office) means they really know me and the car, and I always get a great loaner. Since Porsche is chipping in, it might not be that much less somewhere else, and I'd still need to rent a car for a couple of weeks.
Hope you're back to Porscheing soon!
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11-26-2013, 04:41 PM
#8
Rennlist Member
11-27-2013, 06:14 PM
#9
My current understanding is that the AOS is a plastic component that is part of the emissions control system, and does not rely on oil lubrication to function.. the weak link appears to be the diaphragm inside the part that performs the actual separation of exhaust gasses from minute oil droplets- with the purpose of re-igniting and burning recovered vapors to reduce pollution.
When the diaphragm fails (in my case) or begins to fail (other cases I've read) it allows oil to invade areas it should not. Apparently even minute amounts of oil gaining access to the combustion area will cause lots of smoke... which is the very sudden symptom I experienced.
Meanwhile, oil invaded the intake and exhaust systems and contaminated everything in it's path.
So far the only effective advice I can relay is that the diaphragm can rupture at 68,000 miles even if you follow Porsche's engineered maintenance schedule to the letter. We know that synthetic oil does not degrade like natural oil, thus removing the need for replacing the oil as often as you suggest.
I could say Porsche engineers know what they're doing lol, and I do actually think that, but clearly this part has a weakness. Right now my strategy would be to replace this part at less than 50k mile intervals to hopefully avoid this.
Thoughts :-?
11-27-2013, 06:35 PM
#10
I am enjoying the uber comfort of the Cayenne as a loaner, it's got damn near everything on it. It feels good to be taken care of a bit in this way honestly.
I dig the glass roof a lot, the heated steering wheel and using the keyfob to open the liftgate is as I approach is fun too. I have to say the whole vehicle is thoughtfully programmed. And in sport mode it actually doesn't wallow all that much lol.
But yes.. I REALLY miss the taughtness of my Boxster- which is what 'Porscheing' really means to me. It's being repaired though, and I hate thinking about how much worse it potentially could have been. Who expects this kind of thing to happen to them?
11-27-2013, 06:45 PM
#11
Race Director
On the surface that sounds like good advice, but can you elaborate on how that would specifically prolong the life of the AOS?
My current understanding is that the AOS is a plastic component that is part of the emissions control system, and does not rely on oil lubrication to function.. the weak link appears to be the diaphragm inside the part that performs the actual separation of exhaust gasses from minute oil droplets- with the purpose of re-igniting and burning recovered vapors to reduce pollution.
When the diaphragm fails (in my case) or begins to fail (other cases I've read) it allows oil to invade areas it should not. Apparently even minute amounts of oil gaining access to the combustion area will cause lots of smoke... which is the very sudden symptom I experienced.
Meanwhile, oil invaded the intake and exhaust systems and contaminated everything in it's path.
So far the only effective advice I can relay is that the diaphragm can rupture at 68,000 miles even if you follow Porsche's engineered maintenance schedule to the letter. We know that synthetic oil does not degrade like natural oil, thus removing the need for replacing the oil as often as you suggest.
I could say Porsche engineers know what they're doing lol, and I do actually think that, but clearly this part has a weakness. Right now my strategy would be to replace this part at less than 50k mile intervals to hopefully avoid this.
Thoughts :-?
My current understanding is that the AOS is a plastic component that is part of the emissions control system, and does not rely on oil lubrication to function.. the weak link appears to be the diaphragm inside the part that performs the actual separation of exhaust gasses from minute oil droplets- with the purpose of re-igniting and burning recovered vapors to reduce pollution.
When the diaphragm fails (in my case) or begins to fail (other cases I've read) it allows oil to invade areas it should not. Apparently even minute amounts of oil gaining access to the combustion area will cause lots of smoke... which is the very sudden symptom I experienced.
Meanwhile, oil invaded the intake and exhaust systems and contaminated everything in it's path.
So far the only effective advice I can relay is that the diaphragm can rupture at 68,000 miles even if you follow Porsche's engineered maintenance schedule to the letter. We know that synthetic oil does not degrade like natural oil, thus removing the need for replacing the oil as often as you suggest.
I could say Porsche engineers know what they're doing lol, and I do actually think that, but clearly this part has a weakness. Right now my strategy would be to replace this part at less than 50k mile intervals to hopefully avoid this.
Thoughts :-?
11-27-2013, 07:49 PM
#12
OK. I'm seriously not just asking for details to be a dork lol....
Just so I know I understand what you're saying-- when you bought your 2002 Boxster you soon discovered a high level of water contamination in the factory supplied oil? And so decided to replace the oil at roughly half recommended mileage? If that's correct, may I ask how much you drive the car annually? Have you ever experienced an AOS issue with the 986?
My usage means it doesn't ever sit idle for longer than a week, and that's only when I travel several times a year. Otherwise I'm about average daily driver at 12k a year, and I faithfully wait for the warmup idle to drop the second time before the car even moves. For me this is a car that should be driven, and one I intend to keep.
I simply mean I see the AOS thing as something fairly important to understand fully.
Just so I know I understand what you're saying-- when you bought your 2002 Boxster you soon discovered a high level of water contamination in the factory supplied oil? And so decided to replace the oil at roughly half recommended mileage? If that's correct, may I ask how much you drive the car annually? Have you ever experienced an AOS issue with the 986?
My usage means it doesn't ever sit idle for longer than a week, and that's only when I travel several times a year. Otherwise I'm about average daily driver at 12k a year, and I faithfully wait for the warmup idle to drop the second time before the car even moves. For me this is a car that should be driven, and one I intend to keep.
I simply mean I see the AOS thing as something fairly important to understand fully.
12-19-2013, 10:39 AM
#13
Follow up
Just getting around to doing a follow up!
Got the car back on 12/14, so about 3 weeks in the shop.
They removed and cleaned the exhaust system, replaced both banks of cat converters, all 4 O2 sensors, 6 spark plugs, 6 ignition coils, mass airflow sensor, air filter, all associated gaskets and seals (and of course the air/oil separator that caused it all)
.... grand total $4793.86
Even though that is a kicker of an unexpected repair bill, I'm very grateful to Porsche for their goodwill in providing about $5k of parts at no charge.
The loaner Cayenne was a nice comfort too, but I missed the sport exhaust wail of my RS60. What's done is done... and this weekend in SE Virginia is forecast to be in the mid 70s, so it's top down at xmas time
Got the car back on 12/14, so about 3 weeks in the shop.
They removed and cleaned the exhaust system, replaced both banks of cat converters, all 4 O2 sensors, 6 spark plugs, 6 ignition coils, mass airflow sensor, air filter, all associated gaskets and seals (and of course the air/oil separator that caused it all)
.... grand total $4793.86
Even though that is a kicker of an unexpected repair bill, I'm very grateful to Porsche for their goodwill in providing about $5k of parts at no charge.
The loaner Cayenne was a nice comfort too, but I missed the sport exhaust wail of my RS60. What's done is done... and this weekend in SE Virginia is forecast to be in the mid 70s, so it's top down at xmas time
04-21-2014, 08:07 PM
#14
2nd Gear
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AOS separator
I have looked at the price of motorsports separator for cayman s and it cost around 1400 to 1700. It is noted in the thread it could cost 500. Any idea where to get it and does anybody know if the new AOS would experience the same diaphragm failure in a tracked car?
Oj
Cayman S 2008
Oj
Cayman S 2008
04-23-2014, 05:11 PM
#15
Oj,
There are two types of Motorsport AOS that can be used. The one for the 996 used to be $500 but interferes with the air pump bracket and requires messing with the bracket. The other version is the 987 part. It costs about $1300 but installation is a piece of cake compared to 996 version.
Rob
There are two types of Motorsport AOS that can be used. The one for the 996 used to be $500 but interferes with the air pump bracket and requires messing with the bracket. The other version is the 987 part. It costs about $1300 but installation is a piece of cake compared to 996 version.
Rob