Porsche 928 Workshop Manual page 803

38
Automatic Transmission / Gears, Valve Body
928
Condition:
No power flow in all selector lever positions for
a brief period immediately after starting engine
(especially when car had not been used for a while)
Torque converter drains partially via leaky OI defective lubricating
ring or valve in input shaft.
Correction:
1. Check lubricating ring on input shaft, replacing if necessary.
2. Checking ball valve in input shaft, replacing input shaft if
necessary.
3. Check and clean lubricating pressure valve in shift valve
housing.
Condition:
No power flow in reverse gear
Correction: 1. Remove shift valve housing, check brake band B 3 and
adjustment.
2. Remove brake band piston B 3 and check seal.
3. Replace one-way clutch in gear set.
Jondition: Strong jolt when engaging selector Lever in "D"
:orrection: 1. Adjust idle speed and CO level to specifications
2. Check modulating and operating pressures. correcting
modulating pressure if necessary.
3. Check vacuum lint and connections for leaks.
Note:
4. Check whether pressure acceptance piston in rear transmission
case moves easily and is installed correctly.
5. Check whether feed bore for pressure acceptance piston in
rear transmission case is plugged.
If there is a hard engagement jolt when quickly shifting back
and forth between "N" and "D" several times, there is no fault.
The pressure pick-up requires a running time of approx. 2
seconds. If this time is given, the engagement jolt will also
be correct.
38 - 14
Troubleshooting
Printed in Germany