Porsche 928 Workshop Manual page 1112

928
Automatic Transmission/Gears, Valve Body
38
ATF level in transmission will change with fluid
temperature. Max. and min. marks on transparent
tank are in reference to an ATF temperature of
80 'C. When ATF temperature is 20 to 30 "C, the
maximum ATF level will be below the minimum mark
(see figure). The amount of ATF between min. and
max. marks is 0.2 liters.
1 = max. at 80 'C ATF temperature
2 = min. at 80 'C ATF temperature
3 = max. at 20 to 30 "C ATF temperature
Add ATF to correct level. Cleanliness is essential!
If ATF level is too low, oil pump will draw in air,
which can be heard. ATF will foam and cause
incorrect readings when checking ATF level. Stop
engine until ATF foam disappears (approx. 2 minutes)
Add ATF and recheck ATF level.
Excessive ATF must be drained or drawn off, since
otherwise transmission components would splash
excessively and raise the temperature too much, until
finally foamed oil is forced out through vent. This
condition could damage transmission on a longterm
basis.
After correcting ATF level to specifications,
operate brake pedal, leave selector lever in each
position (R-N-D-N-R) several seconds and then
return it to "N", IO that working pistons of power
parts are filled with ATF. Recheck and, if
necessary, correct ATF level.
C -Stall Speed Test
This check provides information on operation of
engine, converter and transmission. It is applied,
when top speed cannot be reached or acceleration
is insufficient.
Note:
During this check all the engine power is converted
into heat in the converter, which is why this test
must not last longer than 5 seconds.
Rear wheels must not be permitted to turn for this
check.
Also engine must be at operating temperature and
develop its full power.
Extra equipment, e. g. compressor for air con
ditioner. must be turned off.
Check must not be made with car's tachometer.
1. Connect tachometer that it can be read from
driver's seat.
2. Run engine at about 2,000 rpm approx
2 minutes prior to testing.
3. Apply parking brake fully and depress brake
pedal with left foot.
Printed in Germany - ~11, 19 86
Checking Transmission Operation 38.103
(Transmission Type A 28.01)