C Inspection.
•
Check lubricant change interval.
This means checking the type of lubricant
used in the transmission. Remember that many synthetic lubes are performance
rated for oil change intervals upward to 500,000 miles, so it is wasteful to change
them more frequently. If an oil change is required, drain and refill the
transmission with the specified oil. Transmission oil analysis can be used to
establish more precise oil change intervals that are better suited to the actual
operating condition of the vehicle.
•
Gearshift lever. (8)
Check for bending and free play in the lower housing. A
lever that is excessively loose indicates wear.
•
Shift tower assembly.
(9) Remove the air lines at the slave valve and remove
the shift tower from the transmission. Check the tension spring and washer for
wear and loss tension. Check the gearshift lever spade pin/shaft finger for wear.
Also take a look at all critical contact points.
1.1.2 Cause of Leaking Lubricants
Oil leakage in standard
transmissions is not common, but
when leaks occur the rear
transmission seal is a common
offender (
Figure 8-4
). A leaking
rear main seal can lead to
complete transmission failure, so it
must be repaired. It can be difficult
to source oil leaks on
transmissions, however, so be
sure to identify the leak path
before disassembling any
components. You can use a
checklist such as the following to
help you identify the source of oil
leaks, but it is most important
before beginning to pressure wash
the transmission, removing all
evidence of oil leaks. Take care
not to directly aim the pressure
hose into the rear main seal.
Rather, use a wiper to clean up
this area. Next, run the vehicle. It
Figure 8-4 - Transmission yoke seal.
can really help to run a vehicle on a chassis dynamomter when attempting to locate
hard-to-find leaks, because leaking oil is not smeared all over the transmission housing
by the air flow.
Transmission oil checklist:
1.
Inspect the speedometer connections. Both mechanical and inductive
speedometers connect to the tailshaft assembly. Check the speedometer sleeve
torque and ensure the O-ring or gasket has not failed. Hydraulic thread sealant
applied to the threads can sometimes cure this type of leak.
2.
Inspect the rear bearing cover assembly bolts for tightness. These fasteners
should be torqued to specification. Thread sealant is required to seal the fastener
8-11
NAVEDTRA
14050A