The original Volkswagen Touareg and Porsche Cayenne may not share an engine, but earlier models do share a transmission: the Aisin AW TR-60SN/09D.
This six-speed transmission is generally reliable, but develops problems with the valve body: the hydraulic fluid control assembly that regulates gear and clutch engagements. The classic valve body symptom is a hard shift from fourth to fifth. “It feels like you’re going through the windscreen,” is how Steve at JZM Porsche described his first experience of the problem.
I’ve been having gearbox problems with my Cayenne for a while now, with the valve body the prime suspect. My 2004 Cayenne S never had a huge problem changing gear: it was much more a clutch control issue, where the car would drop out of gear while waiting to pull out of a T-junction or onto a roundabout and leave you stranded at first, but suddenly find second, tearing off with a highly undignified bang. Cue eyeliner streaks on back-seat teenage cheeks.
The experience was most unbecoming, so I decided to fix it. The Internet provided two firms in the UK known to repair Cayenne valve bodies (mine shown above) by reaming the worn valve passages out and inserting bigger valves, and refurbishing solenoids where required. The cost was less than half that of a remanufactured Porsche part, said to solve the problems discovered in the earlier Cayennes.
I emailed the first firm. The owner answered a couple of my messages but stopped when I asked for a few more details on the process for a magazine article. The other firm’s contact was more amenable and sounded like he knew his stuff. We stripped the valve body out of the car and sent it away. It came back refurbished, we refitted it and the car hasn’t worked since.
We’ve tried two different valve bodies, both supposedly testing fine on the bench but not working in the car. I can get gears 1, 2 and 3 ok, but when it hits the shift to fourth, the display says it has shifted but the car drops out of gear, as if you’ve stepped on the clutch. It will rev away doing nothing, then it throws a gearbox fault and limp mode follows.
I’ve bitten the bullet and ordered the Porsche replacement valve body at £1030 plus 20% VAT. Plus another round of trans fluid changes and work time lost, and whatever bill I get for these unsuccessful valve bodies (one my original, the other going back). You can be sure of small claims repercussions there.
Learn from my mistakes. If you’ve got a reliable Subaru, stick with it. Do not buy a used Porsche Cayenne! Add this to the classic Cayenne problems of coil failures, coolant pipe failures, control arm fails, screenwash leaks and ECU destruction and so on and it gets very expensive to run a used Cayenne. Not to mention what happens when your engine fails – as many V8s and Turbos do.
Anyone well versed in auto gearboxes with some thoughts on the 4-5-6 issue, kindly drop me a line. We have triple-checked wiring connections, fluid levels, filters, pressures, gearbox operating temps and it works fine in first through third, if not as smooth as original. Very disappointing not to have the car outside the door, but we will sort it out eventually.