- Author: Ed Lee, Contributing Editor
- Subject Matter: ZF5HP19
- Issue: Shifter can’t tolerate heat
A 1997 Porsche Boxster was towed to a transmission shop. The vehicle was equipped with a ZF5HP19 transmission (Porsche calls this transmission A86.00 Tiptronic) and had 48,408 miles on the odometer. The customer complaint was that the vehicle would drive fine when cold, but the warmer the transmission got, the greater the effort to move the shifter. The shifter would get to a point that it would not move at all. At one point the shifter assembly broke because of the force applied to it.
The vehicle had previously been to a Porsche dealer for the shifter repair. The dealer replaced the shifter assembly and the shifter cable at a cost of more than $1,900. The dealer told the customer that the restricted movement was an internal transmission problem and would cost an additional $10,000 to replace the transmission. That is when the vehicle was taken to the transmission shop. The shop verified the complaint and disconnected the shifter cable at the transmission to isolate the problem. With the cable disconnected the shifter and cable moved freely. Next the pan was dropped and the technician again tried to move the shifter lever. The lever would not move and an attempt was made to move just the manual valve. The manual valve was stuck solid. The valve body was lowered and as soon as it was allowed to cool the manual valve moved freely (figures 1 and 2).
In 1997 the manual valve in the ZF transmissions was made of “Bakelite.” This proved to be a bad idea and this practice only lasted one year. As the transmission temperature increased the valve would expand and seize in the bore.
The good news is: the aftermarket sells this valve separately for about $6. This same manual valve is also used in several other ZF transmissions so it is possible to get a replacement valve from a donor transmission.
The bad news is: if you owned one of these vehicles, you could have the shifter assembly, shifter cable, and transmission replaced and still have the same problem. Locally, there is a 1997 Audi with very low mileage that was never able to be fixed – until now of course.
Needless to say, the owner of the Porsche Boxster was elated. His bill was considerably less than his $10,000 estimate.