My 2015 Panamera 4 is just under 60K miles. I am doing the 60K Service and part of what I will be doing is walnut blasting the intake valves (this will be my first time with this). After removing the intake manifold, I looked in all intake ports and found a possible cause for concern on Intake port for Cylinder #5. This is the port with most oil and is the worst looking one. This port also happens to be under the AOS (also know as Crankcase Vent Valve). I have also noticed some oil consumption after ~2500 miles since the last oil change, possibly 1/4 - 1/2 qt. I have attached photos of all Cylinders. By looking at Intake 5, could that indicate a possible failed or failing AOS?

Intake Port for Cylinder 1


Intake Port for Cylinder 2


Intake Port for Cylinder 3


Intake Port for Cylinder 4


Intake Port for Cylinder 5


Intake Port for Cylinder 6


Thank you for any input!

 

Looks normal, considering the AOS is near cylinder 5.

I view PCV and AOS components as replacement items at high mileage, loosely defined. Since you are "in there" already I would replace any PCV and AOS components you have removed during the intake valve project.

If you intend to keep the car as long as possible, replace these plastic parts which easily plug and sludge with oil residue.

 

Agree with the above.... I would actually say the intake valves look pretty clean. But yes, suggest replacement of the AOS. Also, pay close attention to the AOS lines as well as they can become brittle from the numerous heat cycles.
Lastly, there are also coolant lines that run under the intake and now would be a great time to inspect/replace.

 

Thank you both for the replies and information. I went ahead and ordered a new AOS and the two plastic lines for it. I was already planning on replacing the coolant breather line (the plastic coolant line that connects to both sides) while the intake manifold is off since that seems like a common failure.

 

This (walnut blasting) is something I've been considering recently. What kind of tools did you need to invest in?

 

Apologies for the late reply @sac02 I wanted to complete the entire service before commenting and here are the tools / thoughts on how it turned out.

I am from the US and tried a small handheld media blaster from Harbor Freight - Specifically the "CENTRAL MACHINERY 18 oz. Portable Abrasive Blaster Gun Kit" - https://www.harborfreight.com/18-oz-...kit-59490.html This comes with shorter nozzles that were not able to reach all the way down to the valves, and I believe the walnut media was getting spread out over too wide of an area. So I got an extension nozzle that fit from amazon at This allowed me to continuously spray (until the compressor tank ran low on air and had to wait some time for the compressor to refill the air tank) but made it much easier. I used this intake adapter with a shopvac to do the blasting -
However I found I had to reload the walnut media many times and became a pain. The winning combo was that extension nozzle paired with https://www.harborfreight.com/air-to...kit-37025.html This allowed me to continuously spray (until the compressor tank ran low on air and had to wait some time for the compressor to refill the air tank) but made it much easier. I used this intake adapter with a shopvac to do the blasting -
Valves look so much more clean! Photo below of the after:




While I was in there, I ended up replacing the plastic coolant line above the V block. Do not be like me and think you can wiggle the new one in even if you can get the old one out, without removing the fuel rail. So I pulled the fuel rail. Also don't be like me and think because you pulled the fuel rail you need to replace the fuel injector o rings. Those actually sit outside each fuel injector and hold it to the injector bracket. I mistook the o-rings for the small black rings INSIDE the injectors and pulled the inners of the injectors out which turned out to be small mesh screens. And they all broke when I pulled them out, so I ruined all of my fuel injectors. So those had to be replaced, lessons learned on my part. But hey, I will also consider it kinda maintenance since injectors CAN go bad... Oh well.

I also ended up replacing the AOS, the AOS lines, intake manifold gaskets, belt tensioner (that was leaking pretty bad), belt tensioner pully, idler pulleys, and drive belt. After the engine bay was wrapped up I ended up changing the PDK fluid and filter, replacing the transmission mounts (they crumbled on the way out to get to the filter), and changed both front and rear differential (final drive) fluids. A large 60K mile service but should hopefully keep the Panamera in good working order! As the new owner of this car (I have only had it under 2500 miles / 2 months), I am happy to know it should be in tip top shape now.

 

On injectors, small mesh can be replaced :

 

AOS stands for Air Oil Separator if I'm not mistaken, so yes if there is a lot of oil getting by it then replace. AOS is more of a "catch can" than a PCV valve.

 

@Marcus13190 Good info on this, I did not know, today I learned! Thank you!

@djdonte My thoughts exactly which is why I replaced that system.

 

Thanks, great info.

What kind of air pressure did you need (currently have mine set to 110psi, but could theoretically go up to 150) and how much walnut media did you go through?

 

@sac02 I had my pressure set to 120 PSI on my compressor, anywhere between 80 and 120 PSI seemed to have good results. I have a smaller air compressor and tank so there was a good amount of waiting for the air to recharge between blasts.

I used a 25 Lb bag of walnut media from Harbor Freight, I probably used about 5 - 10 lbs for all cylinders, there is still quite a bit left.

 

If your air oil separator went out, I would strongly suggest after placing all of its related houses. There have been several instances around where an air oil separator being replaced on a Porsche engine, or a Volkswagen or Audi engine, can later cause oil leaks. This is particularly true turbo charged cars as apparently the oil separator system helps keep boost out of the crank case. there’s a Panamera in my local dealer right now that’s had to have its entire engine gaskets replaced, including rear, main, front main and timing chain cover boxes, etc. It is a turbocharged car. This is also a problem on the V8 Cayenne that are turbocharged as well.

 

PCV systems on modern engines are a liability and regular maintenance items.

PCV = fresh air intake into the crankcase + oil vapor exhaust out of the crankcase.

Fresh air intake into the crankcase includes small diameter tubes and check valves, starting downstream of the air filter and leading into the crankcase. These do not see too many failures because in relative terms the air is cool, and there is no oil vapor present. But if these tubes or check valves become blocked, excessive vacuum can build in the crankcase, sucking in seals and failing them. MB 4.0TTV8 is doing this in the field.

Oil vapor exhaust out of the crankcase is where most problems happen. Anything on this side of the PCV system can and does get sludged with oil. Both MB and Porsche have current problems with failures of this side of the PCV system. This side of the PCV system (tubes, check valves, AOS, etc.) should be replaced before 100k miles. 50k-70k miles seems about right.

Carmakers have pushed the bubble in the wallpaper (oil vapor sludge) from the back of the intake valves to the AOS. Hard to say if any progress has been made, because it’s arguable little harm is done from intake valve deposits. It’s clear what harmful effects failed PCV components can cause (failed RMS, blown up intake manifolds, etc).

 

Do you have a part number for the mesh filter? I am looking to change these out on mine before I put the intake back on.

 

I bought mine through this firm.
https://injector-rehab.com/product/b...x-13mm-filter/

Do note it is recommended to replace the teflon seals anytime the GDI injectors are removed, but requires special tools to install/compress the new seals... I suspect a person could reinstall w/out issue...