Buick LeSabre 1965 Service Manual page 361

SUPER TURBINE "400'
TROUBLE DIAGNOSIS 5 - 1 4 7
SECTION 5-E
TROUBLE DIAGNOSIS
CONTENTS OF SECTION 5-E
Paragraph Subject Page
5-37 Diagnosis Procedure 5-147
5-38 Diagnosis Sequence 5-147
5-39 Diagnosis Guide • • 5-147
5-40 Oil Leaks • • 5-148
5-41 Possible Points of External
Oil Leaks 5-148
Paragraph Subject Page
5-42 Super Turbine 400 Transmissions-
Oil Pressure Check 5-148
5-43 Transmission Oil Leaks 5-149
5-44 Possible Points of Transmission
Oil Leaks 5-149
5-45 Super Turbine 400 Diagnosis Guide
Transmission Problems and
Related Causes 5-149
5 - 3 7 SUPER TURBINE
4 0 0 AUTOMATIC
TRANSMISSION
TROUBLE DIAGNOSIS
PROCEDURE
Accurate diagnosis of transmis-
sion problems begins with a
thorough understanding of normal
transmission operation. In par-
ticular, knowing which units are
involved in the various speeds or
shifts so that the specific units or
circuits involved in the problem
can be isolated and investigated
further. Analytical diagnosis will
protect the technician from come-
backs and certainly will improve
owner satisfaction.
An important and often overlooked
aspect of diagnosis is finding out
specifically what the customer is
complaining of. For this purpose
a short ride with the customer
will often prove beneficial. It may
be found that the condition the
customer wants corrected is
s t a n d a r d and should not be
altered.
The following sequence, based on
field experience, provides the
desired information quickly and
in most cases actually corrects
the malfunction without requiring
the removal of the transmission.
Details of the items listed in this
sequence are covered further in
the text.
5 - 3 8 SEQUENCE FOR
DIAGNOSIS I N THE
SUPER TURBINE 4 0 0
1. Check and correct oil level.
2. Check and correct detent and
stator switches.
3. Check and correct vacuum line
and fittings.
4. Check and correct manual
linkage.
5. Road Test
Install line pressure gauge and
road test, (correcting Items 1, 2,
3, and 4 on previous page may
have eliminated the complaint.)
a. Road test using all selective
ranges, noting when discrepancies
in operation or oil pressure
occur.
b. Attempt to isolate the unit or
c i r c u i t i n v o l v e d in the
malfunction.
c. If engine performance indi-
cates an engine tune-up is re-
quired, this should be performed
before road testing is completed
or transmission correction at-
tempted. Poor engine perfor-
mance can result in rough shifting
or other malfunctions.
d. If the malfunction or complaint
is determined during road test,
check list of transmission prob-
lems and related causes as de-
tailed in this diagnosis section.
After having used the above
sequence to find the source of
the problem, the cause of the
problem can be corrected.
5 - 3 9 OIL LEVEL CHECK
Always check the oil level before
road testing. Erratic shifting,
pump noise, or other malfunctions
can in some cases be traced to
improper oil level.
1. Oil level should be checked
with the selector lever in the
Park (P) position, engine running,
and the vehicle on level pavement.
2. CAUTION: With unit at room
temperature (engine running) oil
must be visible on dipstick prior
to operating the vehicle.
3. Bring the transmission oil to
operating temperature of 170° F.
(This can be accomplished by
driving approximately five miles
with frequent starts and stops.)
If oil level is low, add automatic
transmission fluid to "Full"
mark.