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08 CTT PDCC Failure, Lessons learned, and a bleeding question
Hey guys, don't hang out around here all that often anymore, but I still check in from time to time I figured some of this was worth sharing, sorry for the long post.
Last night while driving the wife's 08 CTT somewhat spiritedly, I heard a loud "pop" and got a chassis failure warning. When I pulled over, I could see tons of fluid all over the right front suspension. Time to call the wrecker. Once I got it home, I realized one of the braided lines had burst causing a huge mess.
The line that failed runs parallel to the line in the top picture. You can see a rubber 'bumper' on the line. It turns out this is to prevent chaffing with the power steering cooler mount
On the failed line, there is visible wear on the line and the mount right where it burst. These lines are under a tremendous amount of pressure, and any small breach rapidly becomes a nightmare. The rubber bumpers are just slid over the lines, and can somewhat easily be slid up and down the line. This is not good for several reasons. If you look at the last picture, you can see the entire sway bar, and the torsion motor in the center. As the system works, this twists providing torque on the swaybar to keep the body level. When it twists, the lines move with it.
The root of the issue lies in the fact the oil filter is directly above the power steering cooler, and PDCC lines. Every time the engine oil filter is changed, the cooler loop is dismounted, and the lines are pushed out of the way. I'm sure during this process one of the rubber pieces was slid on the hose just enough to allow contact with the mount.
I would strongly suggest you take a look at yours and make sure the rubber pieces are preventing any contact. (there are actually three on one hose and two on the other) You do have to pull the under tray off, which is pretty simple.
Fortunately, I still have fluid left in the reservoir, so hopefully my pump is ok. If run dry, even for a short time, the pump can be ruined. $$$$
It is also scheduled maintenance to replace the fluid reservoir every 48k miles or so. ($45.00 from the dealer)
I'm getting quite the education on this system, and while very, very cool, it's not without its idiosyncrasies. I also learned that the durametric tool does not have the functionality to properly bleed the system
Does anyone know if there is a way to manually bleed the system, or do I need to load it on the trailer for the 60 mile trip to the dealer for that?
I hope this helps some of you overt disaster on your p!gs.
Wow, that's really unfortunate! Thank you very much for posting the warning.
When I picked up my '08 CTT with PDCC about 10 months ago, I changed the oil and discovered that the lines down there were never correctly returned to their proper positions. It took my a while to sort out exactly where things were supposed to go and I also found out that one of the rubber mounts had been broken by the dealer who had done almost all the service.
This is a very timely post as I am going to change the oil next week. I will check again to ensure that everything is in its proper place and secured.
Do you know if the reservoir is difficult to replace? I assume that mine has been replaced, but that is the only item that I do not have in the service records.
The reservoir is a simple change. If you pull the plastic cladding on the driver's side of the engine bay it's easily accessible. I'm really hoping I can find a solution to the bleeding issue.
I went to pick up the new hose and reservoir today and Porsche has made some improvements. The new hose has a rubberized coating, and there is an additional spacer to install.
After speaking with the lead tech, he walked me through the bleeding procedure. Basically, run the car at idle for 10 minutes to let the system stabilize, then they run a program with the PIWIS to open the valve blocks to fully exercise the system. We both agreed that if the fluid returning to the reservoir was free of bubbles, and there were no system faults, it would be just fine to go exercise the system by driving to cycle the valve blocks. If I get any system faults, or pressure warnings, or if there appears to be air bubbles, my plan is to trailer it over to them to run the full bleed.
I went to pick up the new hose and reservoir today and Porsche has made some improvements. The new hose has a rubberized coating, and there is an additional spacer to install.
After speaking with the lead tech, he walked me through the bleeding procedure. Basically, run the car at idle for 10 minutes to let the system stabilize, then they run a program with the PIWIS to open the valve blocks to fully exercise the system. We both agreed that if the fluid returning to the reservoir was free of bubbles, and there were no system faults, it would be just fine to go exercise the system by driving to cycle the valve blocks. If I get any system faults, or pressure warnings, or if there appears to be air bubbles, my plan is to trailer it over to them to run the full bleed.
I'll update after it's done
Thanks very much for the update. I will be ordering a new reservoir next week. Do you think the spacer is available separately from the hose? Also would you kindly post the part numbers for the reservoir, etc... the techs at my dealer are okay, but the parts department is seriously challenged. I may just order from Suncoast...
Bled the system, and it seems to be okay. At first it sucked the reservoir almost dry and foamed really badly. I filled it up again and the foam decreased after 1 or 2 minutes. I also cracked the bleeders on the sway bar, and got a good bit of air out. Let them run until good clean fluid came out.
No error codes, and the level is stable and foam free. Not too bad a job after all. Total cost under 150.00
Bled the system, and it seems to be okay. At first it sucked the reservoir almost dry and foamed really badly. I filled it up again and the foam decreased after 1 or 2 minutes. I also cracked the bleeders on the sway bar, and got a good bit of air out. Let them run until good clean fluid came out.
No error codes, and the level is stable and foam free. Not too bad a job after all. Total cost under 150.00
Great work. It is very encouraging to hear that the PDCC system can be serviced by us mere mortals!
I replaced the PDCC and power-steering tanks/filters, both PDCC lines, and it only needed 9/10ths of a liter of Pentosin CHF 202 to refilll both. No bleeding required, but I did have to put the front wheels back on the ground to get the chassis warnings to go away.
Reviving an old thread here. I just had a PDCC line blow at about 60 mph on a seriously (properly) banked 270-degree offramp while getting off the freeway. There was a loud pop as I set up the corner and the "suspension failure" warning came up. When it went, it felt exactly like a sway bar link giving way...but with more control. I pulled off the ramp into a parking garage and shut it down. The PDCC system then dumped ton of fluid on the ground. I had it flatbedded home and have the replacement lines on order.
Before the trolls jump in here and say, "this is why I won't have a car with PDCC..." I am still very impressed with the engineering of the system, just not the mounting for the lines. After 78k miles,
it failed while I was pushing it really hard and the failure happened in the way it should, without loss of control or complete failure. Stange to say but the failure was actually confidence-inspiring in the vehicle and in the technology. A real sway bar link failure in such conditions would have been a lot more catastrophic. I still will only own a modern Porsche with PDCC!
Funny how I am back posting in this thread out of necessity three years and a different Cayenne later. I'll keep you all posted as to how the repair goes...
Reviving an old thread here. I just had a PDCC line blow at about 60 mph on a seriously (properly) banked 270-degree offramp while getting off the freeway. There was a loud pop as I set up the corner and the "suspension failure" warning came up. When it went, it felt exactly like a sway bar link giving way...but with more control. I pulled off the ramp into a parking garage and shut it down. The PDCC system then dumped ton of fluid on the ground. I had it flatbedded home and have the replacement lines on order.
Before the trolls jump in here and say, "this is why I won't have a car with PDCC..." I am still very impressed with the engineering of the system, just not the mounting for the lines. After 78k miles,
it failed while I was pushing it really hard and the failure happened in the way it should, without loss of control or complete failure. Stange to say but the failure was actually confidence-inspiring in the vehicle and in the technology. A real sway bar link failure in such conditions would have been a lot more catastrophic. I still will only own a modern Porsche with PDCC!
Funny how I am back posting in this thread out of necessity three years and a different Cayenne later. I'll keep you all posted as to how the repair goes...
Cheers,
TomF
Tom, did your line that failed abrade through the stainless and was it a raw stainless line or one of the newer style braided stainless with some type to polymer coating over it?
12-29-2014, 10:39 PM
08 CTT PDCC Failure, Lessons learned, and a bleeding question
I figured some of this was worth sharing, sorry for the long post. 
