Transmission noisy in
Neutral
1.
Worn or damaged front bearing
2.
Worn or damaged gears
3.
Lack of lubrication
4.
Countershaft gear assembly bearings worn
or damaged
5.
Output shaft pilot bearing worn or damaged
6.
Countershaft gear antilash plate worn or
damaged
7.
Lubricant contaminated with broken bits of
gears, bearings, or other parts
1.
Replace bearing
2.
Replace gears
3.
Fill to filler plug
4.
Replace bearings, countershaft gear, and
countershaft
5.
Replace all rollers
6.
Replace plate or countergear as required
7.
Disassemble, clean and repair transmission
Transmission noisy in
direct drive
1.
Defective front (input shaft) bearing
2.
Defective output shaft bearing
3.
Defective synchronizer assembly
4.
Defective speedometer gears
1.
Replace bearing
2.
Replace bearing
3.
Replace damaged parts
4.
Replace damaged parts
Transmission noisy in
reduction gears
1.
Defective countershaft bearings
2.
Defective synchronizer assembly
3.
Counter gear or bushings worn, loose
1.
Replace bearings
2.
Replace damaged parts
3.
Replace damaged parts
Transmission noisy in
overdrive gears
1.
Defective countershaft bearings
2.
Defective synchronizer assembly
3.
Counter gear or bushings worn, loose
1.
Replace bearings
2.
Replace damaged parts
3.
Replace damaged parts
Transmission noisy in
reverse
1.
Defective reverse idler gear
2.
Defective countershaft bearings
3.
Defective reverse synchronizer
4.
Counter gear or bushings worn, loose
1.
Replace gear
2.
Replace bearings
3.
Replace damaged parts
4.
Replace damaged parts
Transmission noisy in all
gears
1.
Insufficient lubrication
2.
Worn or damaged bearings
3.
Worn or damaged gears
4.
Wrong lubricant
5.
Excessive synchronizer wear
6.
Defective speedometer gears
7.
Transmission misaligned
8.
Excessive input or output shaft and/or
countershaft gear endplay
9.
Contaminated lubricant
1.
Fill to filler plug
2.
Replace bearings
3.
Replace gears
4.
Drain and fill with recommended lubricant
5.
Replace synchronizer
6.
Replace gears
7.
Correct alignment
8.
Adjust endplay
9.
Disassemble, clean, and repair transmission
Figure 8-2 - Transmission quick reference diagnosis chart (cont).
1.1.1 pecting the Transmission
A good preventive maintenance program can help avoid failures, minimize vehicle down
time, and reduce the cost of repairs. Often the transmission failure can be traced
directly or indirectly to poor maintenance.
Daily Inspections.
Many of the practices listed here are part of the driver/operator pre-
trip inspection:
•
Air tanks.
Drain air tanks to remove water or oil. To be sure of removing all liquid
contaminants from an air tank, the drain cock must be fully opened and all air
discharged. Most of the liquid will drain from the tank after the air has been bled.
•
Oil leaks.
Visually check for oil leaks around bearing covers, PTO covers, and
other machined surfaces. Check for oil leakage on the ground before starting the
truck each morning.
•
Shifting performance.
Report any shifting performance problems such as hard
shift or jumping out of gear.
A Inspection.
The following should be checked at each A or lube inspection.
•
Fluid level.
Remove filler plug(s) and check lubricant level. Top off if necessary
and tighten plugs securely.
•
Fasteners and gaskets.
Use a wrench to check the torque on bolts and plugs,
paying special attention to those on PTO covers/flanges and the rear bearing
cover assembly. Look for oil leakage at all gasket mating surfaces.
8-9
NAVEDTRA
14050A