Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2
This step tests for the proper release of the clutch. If the clutch reserve is not correct, the mainshaft gears may be turning, causing the gear to clash.
- 5
This step inspects for the proper transmission fluid. The proper fluid is required for the correct lubrication of the synchronizers.
- 7
A static shift test is performed by shifting into all of the gear positions with the engine not operating. While performing the test, you should note how the shift lever movement feels. Also, while shifting from one gear to another, feel for binding in the shift rails. You should be able to feel the detent plungers operating when coming out of a gear and going into a gear. Excessive play in the gear shift lever may prevent the shift forks from fully engaging the synchronizer.
- 9
A dynamic shift test is performed by shifting into all of the gear positions with the engine operating at idle. Test for the correct mesh of the synchronizers and for the clutch releasing correctly. Move the shift lever and feel for the synchronizer sleeve to just release from the gear then let up on the clutch pedal. Press the clutch pedal and move the shift lever to engage that gear again. If the transmission shifts back into the gear without clashing, the clutch is releasing correctly and the synchronizer is operating. If clashing occurs, test another gear. If all gears clash, the clutch is not releasing correctly.
| Step | Action | Yes | No |
|---|---|---|---|
| DEFINITION: Noise from the transmission when shifting gears. A grinding or grating sound when the synchronizer sleeve is engaging with the selector teeth on the speed gear. A suspected internal transmission condition if the noise is only happens in one gear. | |||
| 1 | Did you review the Symptoms - Manual Transmission (MJK, MH3, or MM6) , or Symptoms - Manual Transmission (M13) and perform the necessary inspections? | Go to Step 2 | Go to Symptoms - Manual Transmission (MJK, MH3, or MM6) , or Symptoms - Manual Transmission (M13) |
| 2 | With the engine operating at idle, does the transmission shift from neutral to any gear without the vehicle lurching or gear clashing? | Go to Step 5 | Go to Step 3 |
| 3 |
|
Go to Step 5 | Go to Step 4 |
| 4 | Repair the clutch system. Did you find and repair the condition? |
Go to Step 11 | Go to Step 5 |
| 5 | Inspect for the correct transmission fluid level and for the correct fluid. Refer to Transmission Fluid Drain and Fill (M13 Without Y4Q) , or Transmission Fluid Drain and Fill (MH3, MJK, MM6) , or Transmission Fluid Drain and Fill (M13 With Y4Q Track Pack With or Without KNR) . Is the transmission fluid level correct and at the correct level? |
Go to Step 7 | Go to Step 6 |
| 6 | Fill the transmission to the correct level or change the fluid if it is the incorrect type. Does the transmission still have gear clash? |
Go to Step 7 | Go to Step 11 |
| 7 |
|
Go to Step 9 | Go to Step 8 |
| 8 |
|
Go to Step 11 | Go to Step 9 |
| 9 |
|
Go to Transmission Shifts Hard (MJK, MH3, or MM6) , or Transmission Shifts Hard (M13) | Go to Step 10 |
| 10 |
|
Go to Step 11 | Go to Diagnostic Aids |
| 11 | Operate the system and verify the repair. Did you correct the condition? |
System OK | Go to Step 1 |