Strosek Ultra

Fred, I just put down the information of how to prime the system in case you need to do that. Over a period of several years I have had intermittent PSD warnings on the red car. The warning usually showed at high speed on roads of minor quality (bumps). As it got worse I decided to take the whole system out and apart for inspection and cleaning. I did not find anything wrong except old dirty fluid and quite some dirt at the front ABS sensors, the rings were really messed up. The car is now back on the road and so far I have had no alarm. Hopefully flushing the system is the only thing you need to do in order to get the system to work properly again. Do clean the ABS sensors and rings. You living in a desert climate oxidation of electric connectors should not be an issue but better check to be sure.
Åke

FredR

Åke

I cleaned the front ABS pick ups during this work programme- they had quite a lot of magnetic pick up on them although I would think the front ABS has nothing to do with the problem but then maybe they create noise on the system as a whole. I may take a look at the rear ones albeit I clenaed those up last year.

You would be surprised as to what can happen over here corrosion wise- whereas we have very little rain on the coastal plain we do have humidity and at times quite a lot of it. The plastics/rubbers get hammered and then [preusmably] the humidity gets to the metal bits. That being said the contacts in the pump and solenoid valve socket connectors looked absolutely pristine. The connectors on the front wheel carriers are in ostensibly shot- I reckon if were to drive the car in the wet and wild UK it would probably grind to a halt in no time.

Rgds

FredR

Have not driven the car yet but this afternoon I managed to do the PSD flush successfully [as far as I can tell]. Once I had broken the PSD nipple stiction yesterday I had to fathom out how to atttack the slave cylinder nipple.

This morning I purchased a very nice rechargable LED inspection lamp- using this I was able to get a better feel for the layout around the diff and realised that I could in fact get a spanner over the nipple approaching it from the differential side of the nipple. I hung a 7mm ring spanner on the nipple and pushed the bleeder tube over the nipple.

The first thing I did was open the PSD nipple and then with the ignition on, ran the PSD pump with the retention clip removed. The pump ran and after some 30 seconds or so it switched itself off with the level dropping to just below the low level mark. I was not expecting the pump to stop at this point so I removed the pump plug. The accumulator gradually pushed more fluid out and when it dropped below the low level mark I pinched the bleed nipple to arrest flow.

I now needed to do the first reservoir replenishment. To achieve this I used a 500 ml plastic drinking water bottle cut into two sections and used the lower half to decant brake fluid into the reservoir putting about 100ml in each shot. I also fitted some paper kitchen towel sheets to the shelf under the PSD unit and around the reservoir bottle to help catch any spillage that might occur [as it did- but not much!].

I thus filled the reservoir to the neck, reopened the nipple and ran the pump. Again the reservoir level dropped some [i.e. the pump was primed], the pump eventually shutoff and the fluid came out of the bleed nipple presumably emptying the accumulator. I ran this cycle several times until the first 500 ml bottle of fluid was exhausted. Difficult to tell when the old fluid was gone and the new stuff resident because the stuff coming out was very clean. I thus decided that when the first 500ml bottle was exhausted I would move onto the slave bleed.

I then ran cables fom the battery positive post and the main earth to attach to the solenoid valva plug. The negative terminal I pushed the 1mm2 cable into the female earth terminal and for the positive I simply hand held the cable onto the positive post for about 6 seconds [i.e. not too long]. First attempt to bleed from the slave cylinder was not too successful- the ring spanner held captive when in the open position was falling down and effectively stopped flow. Pulled the hose off, removed the spanner, put the hose back on and opened the bleed without the spanner sat on it. This time the fluid flowed. When the fluid stopped coming out I filled the reservoir, ran the PSD pump and another batch of fluid came out. I repeated this cycle until the second 500 ml bottle of brake fluid was nearly exhausted. Tightened the slave nipple, put the clip back on the PSD pump connector, plugged it back on the pump and ran the pump. Topped up the reservoir to the full mark and called it a day. The fluid that came from the slave cylinder was noticeably more cloudy than came from the PSD unit so a tiely change I suspect and a reminder why it needs to be done [last time was over 2 years ago].

My preparation activity paid off and I am pretty confident were I to do this again it will be achieved in about 1 hour. Some pics below

Many thanks for the support.

Rgds

Fred

Randy V

Let us know if the green PSD light flashes during a traction loss event.

After I flushed my PSD it turned off the DIFFERENTIAL CONTR. OFF warning notice, but I don't see the green light in the instrument cluster light when the PSD kicks in, like it used to.

Not sure if it's just a bad indicator light bulb? Isn't the instrument cluster supposed to illuminate all indicator lights when the ignition is placed in Position 2? On mine the only one that illuminates is the ANTI-LOCK warning.

FredR

Randy,

No idea what is oging on with yours- on mine the display is as per the attached shot when the ignition key is intalled and moved to position 2- the PSD lamp is illuminated as are several other lamps but the main alarm display panel is not illuminated at all.

Still no idea as to why the oil pressure gauge goes full scale the way it does in this state but in operation it seems to work as it should.

Should be in a position to do some road testing either tomorrow or Friday.

Rgds

Fred

FredR

Took the thing for a test drive this afternoon- over the speed bumps no alarm just a PSD lamp when I gassed it rolling off one of the bumps.

Whether I have cured my original problem the jury is still out on that one but looking good so far.

skpyle

Well done, Fred!

AO

Fred,
THanks for documenting your issues with flushing the PSD. You encountered many of the common issues, so this will undoubtedly help others in the future. Now that I think about it, it's probably been a more than 4 years since I last did mine. It's probably due. (yay.... )

FredR

Hi Andrew,

What surprised me was just how easy it was to do this procedure once the ground work was done. It is not that long since it was last done on my 928 but anything with brake fluid in it needs changing regularly irrespective of use and the fluid that came out of the PSD slave looked distinctly cloudy whereas the stuff that came out of the accumulator was very clear.

Took the car for a run this afternoon and over the speed bumps it behaved impeccably with the green light coming on if I tried to hoof it and no alarm at all. Not sure why the alarm is no longer illuminating- the contacts in the pump and solenoid valve connectors were very bright as were the pins in the control signal connector. The wiring and other bits and pieces in the wheel well looked immaculate so I did not even touch them.

Rgds

Fred

Strosek Ultra

Fred, a couple of questions for you. From picture I see you have a rubber strip or whatever it is called in English at the edge of the aluminum sheet metal sitting below the PSD unit. Is that original, I do not have it in the red car? How did you do with the wheel well liner, did it fall apart in pieces as mine almost did? A few weeks ago I tried to order WW liners from Porsche in Germany and the reply was "nicht lieferbar" (not available). They did not say anything about a delivery time for the next batch to be in stock.
Åke

FredR

Åke

That strip has been present since I acquired the car 11 years ago and I assume it is original equipment but I do not know that for a fact.

The wheel well liner still confuses me a bit. As I remember what I have fitted at the moment is identical to what I had in my 90 S4 and that is a pair of thermo plastic baffle plates- one at the front and one at the rear of the wheel well shaped to the contours. If I understand the wheel well liner concept correctly I presume this would be similar to the front well with another moulded plastic inset that sits over the top of the two plates I have and mounts via two brackets in the ceiling of the wheel arch [that are present] and thus acts as a splash shield.

Over here we do not drive in wet conditions other than the odd day or two and even then we avoid driving in such conditions because the oil rises to the surface of the tarmac and the roads become treacherous. When I removed the rear plate to get to the PSD unit it was rather dusty in there so I put my eye goggles on and blasted the entire arch with air and after that washed everything with soapy water before I considered opening the reservoir cap.

If I was ever to drive the car in say the UK I would consider sealing the sides of the plastic plates I have in there with some kind of silicon sealant like we have these days in bathrooms etc.

Rgds

Fred

Tomkat80222

Here is what my instruments look like with the key in the on position. It looks like your oil pressure gauge is not working correctly or maybe it's mine. It would make sense that the pressure would be at 0 before you turn on the engine. As far as the differential warning, I 've never had that come on. Just the PSD as needed.

I highly recommend getting wheel well covers from Jerry Feather. I have had them for a few years now and they are still like brand new. He should be able to pack them together in one box. I can understand you don't have to driving in water, but I would be worried about a rock or sand blasting the PSD area.

FredR

The cover that are fittted [not shown in my pics] seem reasonably robust such that I might never have known something else was supposed to overlay them. The PSD system seems well protected from water ingress but as I said earlier it was a bit dusty in there but then so are my underpants- the dust literally does get into everything here!

Jerry's covers do look the business- if and when I manage to fix the remaining mechanical items I am a bit concerned about [mostly suspension] i will get around to those.

My pressure gauge still does some weird things- as you can see at ret it is pegged but still no idea why even though i have posted about this previously. Once the motor is running it behaves more or less as expected and when the engine is shut down -boing- off it goes to full scale deflection. I have had the dash panel out and and checked the connector strips, replaced the wiring from the 14 pin to the sender which is also new. The wires are connected to the sender a bit Heath Robinson in that we used a red crimp connector- crimped one side for the wire and push fit over the sender prong with the other half. It forms a very positive connection but whether there is some signal/earth leakage I do not know. Brasses me off and if anyone can suggest how to diagnose or fix this problem I would be delighted

Dave928S

I have that rubber sealing strip on my car too, and as it was one owner before me, and dealer serviced, I would assume it's original. I can't for the life of me find it in PET It's a bit like looking for something in the supermarket when you have no idea what category they've put it in ... looked under obvious sections such as lock control and body.

Strosek Ultra

I did a search too, both PET online and on my old mikrofilm catalog and I cannot find the rubber strip nor the sheet aluminum piece it is sitting on.
Åke