Porsche Boxster 987.2 pdk whine sound

Hello Guys! First post here. Its great place of knowledge I need your help with my car. Ive got porsche boxster 987.2 PDK 2012 with low mileage (32k km). It makes strange whine sound. Its connected with RPMs. Its started 2 months ago and its getting worse. I was in 2 mechanic shops (one porsche specialist, another automatic gears specialist). Checked steering pump, AC - this side is ok (no belt, still whining). PDK oil is also ok. First mechanic told me that it could be something with PDK , thats why I came to specialist of automoatic gears. He told me that he couldnt find anything... (no dismantle) PDK is working good, no jerking and so on. Car has aftermarket exhausted system and I am curious If it could be connected? I am digging in internet but couldnt find anything :/ Thank you for all tips. Hubert

whine under car

whine during driving

Since the noise is strictly correlated to the engine RPM, independent of even or odd gear selection, means that the source of the noise needs to be before the clutches fo the PDK . Everything after that should either change RPM with even or odd gear, or with the speed of the car. So only the parts indicated in yellow on the schematic below are always rotating at the speed of the engine (at the left of this image). So that means that in the part of the drivetrain depicted in the schematic above, we have only a few bearings that might be affected. I'd not exclude a component outside of the gearbox just yet ... Does the noise loudness or characteristics change with load(/torque), or is it really only correlated to the engine rpm? EDIT: inside the gearbox there is also the pump that generates the pressure for the actuators. I expect that to be running together with the engine (before the clutches) EDIT2: Two interesting videos from a reputable forum member might make this more easily understandable:

Its correlated with engine speed like in video. Is it any chance to check where is it located without dismantle everything? Even after dismantle gearobox how to check which bearing? Noob question: Is it possible to start engine without gearbox? Thank you for your help!

I think @glennvdb has given you a few big clues where the problem might be. And I understand why you want to know if the engine can be started with the gearbox not connected - - if in that case the noise goes away you've isolated it to the gearbox. There are a number of people here who I hope look in on this thread since they have gotten deeper into the PDK transmission than most Porsche shops have.. Oh - I forgot to answer about starting the engine with the transmission disconnected - to me - that's a maybe. Maybe if you don't disturb the flywheel in removing the transmission from it and you leave it more or less in place with all the wiring connected - maybe the engine might start and run. Or maybe not. I haven't heard of anyone doing it..

Do you think It could be related with differential? It is not connected with engine speed isnt it?

The differential is after the entire gearbox, so cannot be the cause of this noise, I'd say. Do you still have access to the bottom of your car? Could you make another video recording the noise in different positions more slowly than the ones you shared before? This could be helpful to identify the source ...

Now, I haven't. I will try organize and make video. Thanks.

What do you think about adding this: 2023 Porsche 911 GT3 RS Coupe 992 4.0L H6 ATF Additive - Liqui Moly (250 ml Tube) - 20040 ATF Additive - Liqui Moly (250 ml Tube) - 20040 www.vertexauto.com

In general - I'm against adding any magic additives to any fluids in a car. If they were useful manufacturers would provide the fluids with the additive package already in the fluid. That said - I did, several times, "fix" a sticky lifter using a top-end oil (light and very aromatic oil additive, supposed to loosen crud and wash it away in the oil..) But both of those times it was on engines much more primitive than the ones in our cars. ATF additives are trying to compensate for some flaw in the transmission. They won't so much fix the flaw as they hide it. This particular one claims it's magic for many parts of many systems in the car besides the AT... that's another hint to me - it isn't designed to address the exact issue you're having. Also you have to consider the PDK is not an automatic transmission, it's an entirely different design, and if you bought this additive, which of the two oils in the transmission would you add it to? You mentioned you have an aftermarket exhaust. Who made it? Who installed it? Is it possible one of the gaskets between the header flanges and the heads has developed a leak? That could cause a whistle and probably will get worse with time/use,.