Cayenne PDCC reservoir .. get it changed .

deMort · 3 Sep 2019

This reservoir has a filter in it , its a 6 year service interval to have it replaced .

i'm starting to see problems with this system as has MarkGolf here , his was the inspiration that got me searching for an explanation as to what's going on here .. thank you Mark.

My guess .. OPC and indeed Indy are not replacing it when due .. it may or may not help but the images and costs make it a worthwhile item to not chance up on and get it replaced .

My second PDCC fault recently .. rear valve body the suspected item but the fault code lists every item of this system so not a lot of help ..

i replaced rear valve body .. all x4 pipes are corroded solid so cant be removed .. cut every one of then off .. we are into £1100 ish at this point .

Second time i've had to do this .. the pipes never come undone so what is an expensive repair becomes a lot more so .

i stripped out the old body to have a look .. the solenoid seals had failed .. that's obvious but there is a fair amount of metal particles inside ..

whilst i agree i cut the pipes so that could introduce metal the oil was flowing out as i cut so would tend to wash it away rather than ingesting it .

My feeling .. a pump or a roll bar is generating metal over time .. an old knackered filter thats not been changed is not catching this debris and its blocking the system .

both have been rears that i've worked on so this seems to be where it collects .

In short .. Make dam sure your pdcc reservoir is changed on time .

Chrome .. open image in a seperate tab to get a bigger picture .. plenty of metal in this valve body .

squelch · 3 Sep 2019

Good shout deMort! Especially as the Porsche Warranty specifically excludes the PDCC Expansion Tank as a wear and tear item!!

MarkGolf · 4 Sep 2019

Nice work Iain!

The PDCC system initially scared me but after getting hands on with it and learning from you, I discovered it is really simple!

I believe the following steps could help someone having trouble with their system.. When I refer to trouble, if you turn the car on and IMMEDIATELY get a warning, I think something electrical (ECU) would be the issue but if like me, you get the warning when you turn or pull away, it will be pressure related, the below may help.

A hopeful fix
Change fluid (CHF11S) and reservoir (The BMW equivalent uses ATF) - Original fluid gets dirty and could contain particles which are blocking the pressure sensors/solenoids.

Beyond the above, you need to get your hands dirty.

Remove and test solenoids with 5v, give them a clean.
Clean pressure sensors

Change seals on the long body solenoids (I want to work out what seals would suit, if the seals are not doing their job, under the HUGE pressure seen in the system, a pressure leak in 1 chamber could cause a chassis error.

Beyond the above and if problems persist, weak/worn pump or bad seals in ARB. According to a Porsche document, a mist of oil from the ARB is OK but if fluid is dripping out and leaving a patch on the floor, the only option is to change the ARB. There does not appear to be a way to dismantle the unit to replace seals.

The issue on my 2008 GTS was a Chassis System error. It would pop up upon hard cornering initially but then developed into appearing when I hit 4mph. I changed fluid/bottle, no joy. I then fitted new pressure sensors, no joy, then I changed a solenoid for one bought from a BMW and cleaned the other, SORTED.
I now want to obtain correct seals and if my error ever reappears, changing the seals on the parts which are original will be my next port of call. I don't think I will need to but I want to have them to save delay.

Iain, thanks for your contribution, this info can really save PDCC people thousands!

deMort · 4 Sep 2019

I think with this particular car then there was no saving it .. far too much debris in the system .. you could in theory pull the solenoids then pour some pentosin through to try and wash out the metal .. but that's not a cheap way to flush it out .

In short i don't really know of anything that could be used .

Solenoid seals had failed along with metal in the system .. that could well cause a future problem .

As you see .. all the pipes had seized .. i also had issues at the other ends ..

Cut pipes .. a very large 2 foot spanner and a socket / airgun to remove the front to rear connections .. thats bad !!

These are never going to be a cheap fix when this corroded ..

The car is also a 2012 so slightly different from the 08-10 GTS .. one of the pipes is modified .. don't get the wrong one .. it doesn't fit well .. as i found out .

Regular change of the reservoir i feel after looking at it and how the filter works.. and i also think .. perhaps every 4 years instead of 6 .

spongebob squarepants · 4 Sep 2019

Iain,
Same on a 991?
:dont know:

deMort · 6 Sep 2019

Whilst the system works on the same principle it is very different between a 991 and a Cayenne .

Trust me if this fault happened on other models i would post about it in the relevant forum

This is Cayenne only but i will add .. if something is due at Time or mileage then its due at that .. 6 years but only 3k mileage is no excuse .. i have examples of just this and it can be an issue .. just do what the book says

SD99 · 8 Oct 2019

Finding this thread quite interesting.

I assume replacing the reservoir makes no difference at all to the Whine on start up?

I`ve never been completely happy with the noise of my pump. Am thinking of getting it replaced. System is functioning fine apart from the noise.

I see the old 955 part has been superseded with 95831402200 and so wonder if that would make any difference to the whine.
:?:

deMort · 8 Oct 2019

A superseded part number often indicates a part has been modified or a newer item from a later model is used .. it may make a difference .

A fluid change is always the first point of call .. cheap but difficult draining the fluid from the lines .. nothing comes undone , but replacing the reservoir replaces a lot of the fluid along with the filter .

As yours is working ok then i would suggest a reservoir change only , this will replace a fair amount of the fluid and is a service item at 6 years.

See what it is like after that before proceeding to the pump .

Matrixxxx · 8 Oct 2019

Just replaced my PDCC tank , not made a lot of difference. on the other forums they have replaced the pump and still have the noise. I have read that some have stopped the noise by changing the fluid with a different type like "royal purple". but not realy a good idea.

deMort · 9 Oct 2019

Pump would be the next logical solution as noises are only caused by 2 things .. a worn pump or air in the system .. a leak which allows bubbles into the system perhaps .

Ive changed pumps on these in the past for noises .. the trouble is what actually caused the pump to wear .

Matrixxxx · 10 Oct 2019

I had a CL55AMG which the tandem hydraulic pump failed from cavitation.

Cayenne PDCC reservoir .. get it changed .

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