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991.2 - Turbo Failure - Oil Leaking from the Compressor
This weekend I upgraded my intercoolers with a set from AMS and found oil upstream of the turbo all the way back to the Intake plenum from my passenger side turbo. I have heard a roamer that there may be a high failure rates of 991.2 Turbo's and wanted to see if this was something that was prevalent.
This weekend I upgraded my intercoolers with a set from AMS and found oil upstream of the turbo all the way back to the Intake plenum from my passenger side turbo. I have heard a roamer that there may be a high failure rates of 991.2 Turbo's and wanted to see if this was something that was prevalent.
I cannot say there is a high or low rate. However mine were both replaced due to the same issue.
there has recently been a thread poster here with someone else observing the similar issue, I’ll find the link.
This weekend I upgraded my intercoolers with a set from AMS and found oil upstream of the turbo all the way back to the Intake plenum from my passenger side turbo. I have heard a roamer that there may be a high failure rates of 991.2 Turbo's and wanted to see if this was something that was prevalent.
We've found the OEM Air Oil Separator is only adequate. Under boost, the crankcase vacuum us supplied by the passenger side turbo inlet. If the AOS does not perform well, it will allow oil saturated crankcase gasses into the turbo inlet. This leaves the residue and potentially liquid accumulation of oil. What you really won't like is when you look into the intercooler down the road from now. The temperature drop the intercooler provides causes oil vapors to condensate and accumulate more rapidly. Oil accumulation is not necessarily bad, to a point, but an oily film on the internal surfaces of the intercooler can reduce the thermal efficiency of the intercooler. What is not known is the long term effects of this on the 991.2. From a performance optimization standpoint, it's not an ideal condition.
We've got several AOS units in Alpha and Beta testing with good results in regards to this issue; eliminating oil build-up on the passenger side intake tract. Testing takes time as we want to assure ideal performance and reliability under varying performance and environmental conditions. We are close
Originally Posted by Rapter
I cannot say there is a high or low rate. However mine were both replaced due to the same issue.
there has recently been a thread poster here with someone else observing the similar issue, I’ll find the link.
I believe that is a pre-991.2 car, so not that same turbos you'd find on a 991.2. Also not certain if it's the same issue or relative to the turbo oiling itself?
We've found the OEM Air Oil Separator is only adequate. Under boost, the crankcase vacuum us supplied by the passenger side turbo inlet. If the AOS does not perform well, it will allow oil saturated crankcase gasses into the turbo inlet. This leaves the residue and potentially liquid accumulation of oil. What you really won't like is when you look into the intercooler down the road from now. The temperature drop the intercooler provides causes oil vapors to condensate and accumulate more rapidly. Oil accumulation is not necessarily bad, to a point, but an oily film on the internal surfaces of the intercooler can reduce the thermal efficiency of the intercooler. What is not known is the long term effects of this on the 991.2. From a performance optimization standpoint, it's not an ideal condition.
We've got several AOS units in Alpha and Beta testing with good results in regards to this issue; eliminating oil build-up on the passenger side intake tract. Testing takes time as we want to assure ideal performance and reliability under varying performance and environmental conditions. We are close I believe that is a pre-991.2 car, so not that same turbos you'd find on a 991.2. Also not certain if it's the same issue or relative to the turbo oiling itself?
Why do these issues with both the turbo chargers and AOS exist on such a premium car?
Porsche has been messing around with turbos for near 40 years... can they get this right and establish quality control along the supply chain? Frustrating....
The post stated that the turbo was leaking but did the OP confirm that? This is a fairly common find on the older gens and the oil comes from the intake system, not from the turbo itself. Pull the hose off and take a look up into the turbo, likely it's completely dry as the oil didn't originate there. As Vektor points out the cause can be the AOS. Not certain if it's the same in the 991 but overfilling the oil can cause this in the 997 turbos. As excess oil gets in the intake it then pools at the hose between the turbo and the IC as it's the lowest point in the intake system.
Not a big deal as it all can be cleaned out. If one is reusing the IC it can be pulled and flushed with mineral spirits or kerosene, important thing is that the solvent evaporates quickly and dries clear.
Edit: The AOS returns to the passenger side which is probably why the OP saw the oil there. My new to me TT has 2 ounces of dirty motor oil pooled on the passenger side while the driver side was completely dry. Virtually certain at some point in the past the oil was overfilled as I've been keeping an eye on it since I cleaned it out and things have been fine. Looking forward to what Vektor comes up with regarding an improved AOS.
Why do these issues with both the turbo chargers and AOS exist on such a premium car?
Porsche has been messing around with turbos for near 40 years... can they get this right and establish quality control along the supply chain? Frustrating....
Just my opinion but the issues don't exist (or are way overblown at a minimum). People overfill the oil because they don't understand how to use the measurement system or don't realize an oil change doesn't completely drain the case and put too much in. Turbo reliability is very good, failures are rare. An oil film in the IC degrades cooling, but it's not the end of the world can be easily cleaned out as I mention above. If you are worried about it add an IC flush to your maintenance list like a belt change. Not selling anything, just passing along lessons learned.
We've found the OEM Air Oil Separator is only adequate. Under boost, the crankcase vacuum us supplied by the passenger side turbo inlet. If the AOS does not perform well, it will allow oil saturated crankcase gasses into the turbo inlet. This leaves the residue and potentially liquid accumulation of oil. What you really won't like is when you look into the intercooler down the road from now. The temperature drop the intercooler provides causes oil vapors to condensate and accumulate more rapidly. Oil accumulation is not necessarily bad, to a point, but an oily film on the internal surfaces of the intercooler can reduce the thermal efficiency of the intercooler. What is not known is the long term effects of this on the 991.2. From a performance optimization standpoint, it's not an ideal condition.
We've got several AOS units in Alpha and Beta testing with good results in regards to this issue; eliminating oil build-up on the passenger side intake tract. Testing takes time as we want to assure ideal performance and reliability under varying performance and environmental conditions. We are close
I believe that is a pre-991.2 car, so not that same turbos you'd find on a 991.2. Also not certain if it's the same issue or relative to the turbo oiling itself?
That is fantastic, I did indeed notice the extra large hose leading to the left side intercooler assembly, but I was not sure if that was it or not. In the old days I would always disconnect the crank case ventilation and PCV and run them to atmosphere. Then I learned to build multistage separators for industrial purposes and started adding "Catch Cans". I am interested to see what you find, with the engine so low auto oil return will be tough and space is certainly at a premium.
I did not pull the compressor suction only the discharge, and there was oil pooling in the housing, intercooler, charge piping, hump hose, TB and intake! Enough that it was dripping out of all the piping.
As for the oil change I change it myself and always add less oil than the manual calls for then add as needed. The last cycle I added 8 qt, brought it up to temp then another 0.5 qt which put me 15% below the full indication. That beings said for most of my other cars I would generally run them on the low side of the indicator for instance the S2000 which is know of eating oil. I might run it say 25% of the indicated Min-Full bar.
Thank you all very much for your input, my outlook is much better today!
Why do these issues with both the turbo chargers and AOS exist on such a premium car?
Porsche has been messing around with turbos for near 40 years... can they get this right and establish quality control along the supply chain? Frustrating....
Well.... Why do the water pumps fail I agree, frustrating.
That is fantastic, I did indeed notice the extra large hose leading to the left side intercooler assembly, but I was not sure if that was it or not. In the old days I would always disconnect the crank case ventilation and PCV and run them to atmosphere. Then I learned to build multistage separators for industrial purposes and started adding "Catch Cans". I am interested to see what you find, with the engine so low auto oil return will be tough and space is certainly at a premium.
I did not pull the compressor suction only the discharge, and there was oil pooling in the housing, intercooler, charge piping, hump hose, TB and intake! Enough that it was dripping out of all the piping.
As for the oil change I change it myself and always add less oil than the manual calls for then add as needed. The last cycle I added 8 qt, brought it up to temp then another 0.5 qt which put me 15% below the full indication. That beings said for most of my other cars I would generally run them on the low side of the indicator for instance the S2000 which is know of eating oil. I might run it say 25% of the indicated Min-Full bar.
Thank you all very much for your input, my outlook is much better today!
Glad to hear it! I remember when I first pulled off the lower discharge hose, oil dripped out, and my heart sank. Thought for sure I had bad seals in the turbo but everything turned out fine. I was pretty surprised how much brownish gunk came out of the IC after sloshing mineral spirits around in it. Probably 90% came out with the first treatment but I did it about six more times until what came out was clear.
Are you the original owner? That discharge hose being so low it effectively acts like a catch can (though not a very good one) so that oil could have been there for years.
Glad to hear it! I remember when I first pulled off the lower discharge hose, oil dripped out, and my heart sank. Thought for sure I had bad seals in the turbo but everything turned out fine. I was pretty surprised how much brownish gunk came out of the IC after sloshing mineral spirits around in it. Probably 90% came out with the first treatment but I did it about six more times until what came out was clear.
Are you the original owner? That discharge hose being so low it effectively acts like a catch can (though not a very good one) so that oil could have been there for years.
I am the first owner and car has roughly 8K miles on it. Since the IC are new, I will drop a QT of oil out of it and then check it again in a few months to see if it is the turbo or I was running the oil too high.
It's very easy to over-fill the oil in these cars! The owner's manual shows that the oil indicator graphic in the dash should NOT be at the top line, but people do it all the time. Even my local dealer likes to "put in a little extra" when they do changes. (I let the dealer do oil changes so it is always documented in Porsche database and on CarFax)
As a public service, here's the owner's manual info on how full engine oil should be. Most would assume "max" is ideal, but nope. I've over-filled before, and it's not ideal.
07-12-2020, 12:56 AM
991.2 - Turbo Failure - Oil Leaking from the Compressor
