Porsche 928 Workshop Manual page 792

38
Automatic Transmission / Gears. Valve Body
928
CHECKING TRANSMISSION OPERATION
Prior 10 making repairs on an automatic trans-
mission. rrouhleshoor rransmission as insrrucied
below and with help from rhr following tests.
A - General Checks
B - Transmission Fluid Level
C - Stall Test
D - Test Drive
E - Pressure Tesl
1mpurtant
All jobs, which require that engine runs, should
only be carried out with selector lever in "N" or
"P" and parking brake applied.
Exceptions: Tests, which require briefly a different
selector lever position.
A - General Checks
Following jobs musr be performed prior to any
resting of rransmission, and if defects are found.
they must be eliminated before continuing with
other work on transmission.
1. Check engine tuning (ignition timing, idle and
tI.ansirion).
2. Check for external damage, e.g. leaks on
transmission (ATF) or final drive (hypoid oil)
and missing or loose mounting bolts.
B -
Transmission Fluid Level
The specified fluid level is extremely importanr
for proper operation of automatic transmission,
so rbar following rest musk be canied out wirh
great care.
Checking ATF Level
Also check appearance and odor of ATF. Buint
friction linings cause a burnt odor. Contaminated
oil could cause failure in valve body.
In this case transmission must be removed and
repaired or replaced.
Test is carried out at engine idle speed, parking
brake applied and selecror lever at "N". Car must
be on level surface.
Let engine run at idle speed 1 to 2 minutes before
checking fluid level, so rhar torque conversed will
be full.
ATF level can be checked o" a cold 01 warm
transmission. However, the level will be more
accurate on a cold rransmission (20' - 30°C/
66' - 86' F ATF temperature). An ATF temperarue
of 80' C/116' F can only be guessrimated.
38 2
Checking Transmission Operation Printed in Germany