From research, I've read that hard shifting problems occur in the 120,000 to 150,000 miles. My symptoms were a bit different that the normal "banging" between shifts. My Cayenne would slip like in neutral when shifted into park and then bang into the normal 2nd gear start.
It may be that fluid changes ever 60,000 miles would reduce these failures. The factory transmission service schedule for the Porsche Cayenne 955 recommends changing the transmission oil and filter every 240,000 kilometers (160,000 miles) or every 16 years.
Valve body R&R isn't much more difficult than a transmission oil service. I found that when the transmission service was done in 2023, there were a few companies that rebuilt these specific valve bodies. There are rebuild kits available but I don't have experience to do that. I didn't wish to wait a week or two for a rebuild to be done so I elected to purchase a new one from a Porsche dealership. It pays to shop around, some dealers are several hundred dollars less expensive than others. It might be possible to find a less expensive one via cross referencing to VW or other channels.
- 20230627_145904 Valve Body LR.jpg (585.01 KiB) Viewed 316 times
- 20230627_140427 Valve Body LR.jpg (377.4 KiB) Viewed 316 times
If anyone needs a core 955-325-039-13 valve body (Cayenne VR-6 and non-turbo V8), I kept mine and don't have a need for it.
Rich
928 OC Membership Chairman
1993 928 GTS Cover Girl
1987 928 S4
1979 928 5-speed rescue soon to be upgraded to 1986.5 level with "beast" internals
1979 928 Euro 5-liter track beast soon to be cannibalized
2009 Cayenne Base