Internal AOS signs of failure

[dphatch]

Can anyone tell me if there are any signs of the failure for the internal AOS for 2007 997 C4S. I have read several posts regarding the primary AOS but none relating to the internal 2 internal versions.

Have replaced one faulty AOS with a tear in internal membrane but would like to rule out issues that may arise with the internal versions before I replace a second primary AOS.

[JFP in PA]

1 hour ago, dphatch said:

Can anyone tell me if there are any signs of the failure for the internal AOS for 2007 997 C4S. I have read several posts regarding the primary AOS but none relating to the internal 2 internal versions.

Have replaced one faulty AOS with a tear in internal membrane but would like to rule out issues that may arise with the internal versions before I replace a second primary AOS.

 

The AOS in the sump are an entirely different system design than the external one that controls the sump vacuum levels, and does not use a membrane.  I can't honestly say that I have ever heard of one of the internal AOS units failing.  If you have already replaced the external unit, and it has failed, I would be willing to bet it was an aftermarket unit (often sold an OEM style unit) which are well known for incredibly poor build quality and short life spans.  Many shops, mine included, only use the factory piece.

[dphatch]

It  wasn't after market as it  was purchased from Sunset Porsche directly,  prt #  997-107-038-00,  in July 2014 .  New part number still ends in 00  so should I expect to get the same  service from it IE..   life span of the factory part ?  Is the racing version of the part worth the $800 + price tag for a street car drive with gusto , but well short of racetrack gusto and that only with the hope a semi-permanent  fix ? 

 

One other question, the 2 parts they call "oil separators " that appear to go to either side of the engine ( in Sunsets parts diagram they carry the same part number as the main AOS  )  do you know what function they serve and should I replace as the same time  assuming they are external and not internal parts ?

Edited August 3, 2019 by dphatch

[JFP in PA]

40 minutes ago, dphatch said:

It  wasn't after market as it  was purchased from Sunset Porsche directly,  prt #  997-107-038-00,  in July 2014 .  New part number still ends in 00  so should I expect to get the same  service from it IE..   life span of the factory part ?  Is the racing version of the part worth the $800 + price tag for a street car drive with gusto , but well short of racetrack gusto and that only with the hope a semi-permanent  fix ? 

 

One other question, the 2 parts they call "oil separators " that appear to go to either side of the engine ( in Sunsets parts diagram they carry the same part number as the main AOS  )  do you know what function they serve and should I replace as the same time  assuming they are external and not internal parts ?

 

If you are suffering issues with the factory AOS, I would be looking at your oil sump level; cold, it should be one to two lines below the maximum level.  Overfilling the sump to the max indication can shorten the lifespan of the AOS.  We see this issue all the time as people tend to fill the oil to the max line and beyond (there is no indication of when the system is overfilled). That said, the factory AOS units, while the best available, are not impervious to failures.  Like brake pads or a clutch, they are considered maintenance consumables.

 

I think the two parts you are referring to are oil scavenging units, which are designed to help get the oil out of the cam covers and back to the sump, and they are rarely if ever replaced.

[dphatch]

Great,  that answers my questions and confirms what I had heard regarding the oil levels and its effect on the AOS. Unfortunately that info was not widely distributed either during the lifetime of the first AOS or that of the replacement so they where both self-destructing as a result.  The owners manual makes no mention of that issue nor did the local dealership when they filled the sump to the line above the "fill line " the few times I let them change it. I will follow that advice from now on and feel better about the potential lifespan the new part may enjoy after the install.  Thanks.  

[JFP in PA]

3 hours ago, dphatch said:

Great,  that answers my questions and confirms what I had heard regarding the oil levels and its effect on the AOS. Unfortunately that info was not widely distributed either during the lifetime of the first AOS or that of the replacement so they where both self-destructing as a result.  The owners manual makes no mention of that issue nor did the local dealership when they filled the sump to the line above the "fill line " the few times I let them change it. I will follow that advice from now on and feel better about the potential lifespan the new part may enjoy after the install.  Thanks.  

 

We fix them for a living, so over time we develop “work arounds” to offset problems like this.  When we get a customer complaining about constant smoke start ups, first we check the sump vacuum level with a digital manometer to make sure the AOS is still functional, then we look at the oil level.  Lowering the oil level just slightly helps, but the part was designed to be serviced on regular intervals, much like the water pumps, which need to be changed out proactively to prevent the impellers from breaking up and getting scattered through the cooling system.  It is just the way things are......