Icarus944

Hi guys, I am new and this is my first post as a member. I've trolled this forum many times, however and you guys are the best!. The dealer recommended a fluid change on my 2009 Cayenne GTS and when I got it back it was really loud. They said it was a bit noisy, but that some get louder as they get older? Nonsense. It wasn't like that before I took it in. I then gave it a bit of a hard drive on a curvy road and one of the lines blew coming out of the front valve block - fluid everywhere - Towed back to dealer. They replaced line... same noise. After a bit of troubleshooting - I looked at the PDCC reservoir which is vibrating big time - squeezed the Power Steering return hose (not the supply) and the system returned to quiet, normal sound. Is this pressure? Could this vibration be from improper bleeding of the PDCC with air pressure causing cavitation somewhere?? Or is there some kind of pressure reducer the dealer could have not put back in when changing the fluid? Why would squeezing the line fix it? This is not the PDCC "hum" that others observe.

CAVU

A few thoughts come to mind in order of likelihood:


- Air introduced after changing the reservoir out and not following the refill procedure.
- Did not follow the very detailed process described in the PWIS.
- Wrong fluid
- Did not shake the Hyd Fluid bottle before use per the instructions (contents settle).

You might ask them to rerun the procedure (from alldatadiy.com, worth the few dollars for a 5 year subscription):

Open the PDCC reservoir -1- . See: Service Precautions
Fill the reservoir with Pentosin until the fluid level remains fixed.
Briefly start the engine, let it run for approx. 1 second and add Pentosin again. During this process, the fluid level in the reservoir may drop quickly. This depends on the quantity of oil required. Therefore, always top up with Pentosin. Repeat this process several times. If the fluid level in the reservoir does not fall any further when the engine is briefly turned over, start the engine again and let it run at idle speed.
Check the fluid level several times at idle speed. If the fluid level is still dropping, keep topping up until the fluid level remains constant in the reservoir. If the oil level drops to the bottom of the tank, or if several air bubbles rise to the surface and/or a significant amount of foam forms in the reservoir, air is still present in the hydraulic system. It is quite normal for a few air bubbles to appear in the reservoir immediately after topping up.
Switch off the engine and set the correct fluid level. The fluid level must be between the -MIN/MAX marking- .


Markings on dipstick (example)

After completing assembly, move the vehicle into an open area to bleed it. See: Service Precautions
Close the doors and lids. Connect the PIWIS Tester to the vehicle.
One worker should sit in the vehicle and select "PDCC" "Maintenance/repairs" "Control unit start-up" in the control unit search on the Porsche System Tester. This includes bleeding and the worker is guided through the menu. The vehicle body will roll to a significant degree. The 2nd worker must ensure complete safety around the vehicle.
Repeat the bleeding process twice. Then open the engine compartment lid and reservoir. Check the fluid level and hydraulic fluid when the engine is running and top up with the required amount of oil. The fluid level must not drop anymore and only a few air bubbles should circulate. There must be a significant reduction in the amount of air bubbles and/or foam formation compared to Step -- 4.
Switch off the engine and set the correct fluid level. The fluid level must be between the -MIN/MAX marking- .
If this is not the case, the bleeding process must be repeated. If the fluid level continues to drop, the system must be visually inspected for any signs of leaks. Repeat the bleeding process following repairs.

MountainStone

That is quite a procedure for bleeding the PDCC system. I had intended to replace my PDCC hydraulic fluid reservoir myself in a few thousand miles (manual recommends at 60K) but it looks like this is a task best left to a dealer.

Petza914

Thank you for that detailed bleeding lrocedure write-up. I'm planning to do this in the next week or so as I'm taking the lines loose to cover them with heat shrink protective clear plastic to prevent any possible abrasion and possibility of a line failure. The new lines available from Porsche actually come this way now - braided stainless with clear protective cover.

Do you know if a Durametric Pro has the ability to put the vehicle into PDCC bleeding mode or does it require the Porsche PIWIS system?

Thanks.

uphoto

Don't let this scare you!

This does not apply to replacing your reservoir!! Your reservoir can be replaced by using a syringe/turkey baster to remove ONLY the fluid from the reservoir, remove reservoir and replace with new. Then top off the fluid with new fluid. You don't need to replace all of the fluid or bleed the whole system.

wkearney99

I'll just chime in here and say, a fine example of why I didn't add the PDCC option to my '17 GTS...

TomF

Yep, and you are missing out on a fantastic option!

Cheers,
TomF

Petza914

+1

After having it, I wouldn't own a Cayenne without it !

wkearney99

Nothing in local inventory had it. Nobody local that I could reach had it. It's a bunch of added hydraulic gear that requires it's own service and may require being R&R when other things need servicing. And the handling it affects is likely never going to see use.

At PECATL I did try an S without PDCC, and a Turbo S with PDCC and there wasn't a significant enough difference in the handling to stand out. This on the road course, but arguably only for a few minutes. Hardly enough time to be certain, but enough to offset any lingering doubts I had about omitting it.

Maybe the, what like, 1500 pound weight reduction over previous model years helps? I don't know.

Meanwhile I'm absolutely delighted with the handling that the '17 GTS offers. Even better with one less subsystem to maintain...

But hey, don't let confirmation bias cloud your judgement.

TomF

LOL.

Something that many don't realize is that PDCC has advantages on potholes and rough surfaces as well. It makes the ride smoother. Remember, the system was introduced on the Cayenne first in an Offroad package...

My CTTS that I am picking up today has PDCC as did my 2008 CTT. I wouldn't have a Cayenne without it.

Cheers,
TomF

Crozzer

I am dredging up old threads trying to figure out why my PDCC line is vibrating and making noise. It was fine. I did the reservoirs, flushed the fluid using the “burp” procedure (connect return line to bucket, crank for a second, refill reservoir, continue until flushed, reconnect return line, and yes my tool runs the bleed program….) about a month later, oil change and maybe mucking about with PDCC expansion loop down there? Now there is a power steering whine, and the PDCC line vibrates. Steering side is solid, no vibrating.

First question; anybody who feels they have a good handle on this, would you go out your fingers on the PDCC line near the reservoir while it is running? Is it solid, or vibrating? (Is this vibrating normal?)

what causes this? What cures it?

I already spent a few K bucks having a bad shop do the power steering pump ($$$). Not fixed. Not happy.

I could try: tracing all the lines to be sure they have the right clips that might dampen vibration? More flushing? Another power steering pump (not excited about that idea…)

any other ideas!? Much obliged.

Crozzer

Hmmm “shake before use” I wonder if this matters, or if “yet another” full flush might help with the whining noise and vibration.

has any body wrestled this bear and won?

manipou

Did anyone find the cause of the PDCC return line vibration? Seems to be fairly common but not much info on a definitive cure?

Crozzer

For me, the key was to replace a few plastic clips along the lines. Definitely put it back in the “nothing wrong” noise level, even if it is “usually” louder than might be expected.

I think I broke one while doing the oil change and was messing with the pdcc expansion loop. (That obnoxious loop in the way of oil changes.). For me the busted clips were behind that loop, and over in the driver side front wheel well.

just trace them on autoatlanta or similar to find the part numbers and help identify any that are missing.

I have heard elsewhere on this forum, and from a Porsche master tech, that this is a commonly overlooked easy fix for the noisy pdcc pump issue.

good luck!

manipou

I had a significant pulsing vibration on the return pipe at the PDCC reservoir at around 1500-1800rpm. So loud it was annoying in the cabin. New PDCC pump from Porsche and now no vibration.