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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 965 (Manual Transmission -- ZF S6-650) >> Diagnostic Information and Procedures >> Transmission Noisy >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 3:  This step inspects for vibration causing a noise. If the vehicle is equipped with an aftermarket box or is carrying a certain load, the driveline axle may not be correct, and could cause a vibration. The vibration maybe resonating into the transmission, causing a noise.
  2. 7:  This step inspects for the correct transmission fluid level. If the transmission fluid level is excessively low, damage may have occurred to the transmission components.
  3. 9:  This step inspects for the correct type of transmission fluid. The transmission uses a special fluid. If the incorrect fluid was used, there may have been an overheating condition. Overheating may cause damage to the transmission components.
  4. 11:  This step inspects for noise coming into the driver compartment. Improper sealing of the shift tower may be allowing normal transmission noise to be heard by the driver.
  5. 21:  This step tests to determine if clutch components are making the noise. Depress the clutch pedal slowly and listen for the change in noise. If the noise changes while pressing the pedal, it may be a faulty clutch component. If the noise does not change until the clutch is completely disengaged, the transmission component is faulty.
Transmission Noisy

Step Action Yes No
DEFINITION: The transmission is making a noise. The different noises may be a whine or a growl caused by faulty bearings or gears. The noise may also be caused by a faulty component, causing a vibration noise or rattle.
1 Did you review the Symptoms - Manual Transmission and perform the necessary inspections? Go to Step 2  Go to Symptoms - Manual Transmission 
2 If the vehicle is equipped with an 8.1L, is the noise present while in neutral? Go to Diagnostic Aids Go to Step 3 
3  Is the noise present at a certain road speed or with a certain load? Go to Step 4  Go to Step 5 
4 Inspect for the correct driveline angle. Refer to Driveline Working Angles Measurement in Vibration Diagnosis and Correction.
Did you find and repair the condition?		 Go to Step 24  Go to Step 5 
5 Is the noise present in all gears? Go to Step 7  Go to Step 6 
6 Is the noise present in just one gear? Go to Step 23  Go to Step 7 
7  Inspect the transmission fluid level.
Is the fluid level correct?		 Go to Step 9  Go to Step 8 
8 Add transmission fluid. Refer to Transmission Fluid Replacement .
Did you find and repair the condition?		 Go to Step 24  Go to Step 9 
9  Inspect the transmission for the correct fluid type. Refer to Lubrication Specifications .
Is the transmission fluid the correct type?		 Go to Step 11  Go to Step 10 
10 Drain and fill the transmission with the correct type fluid. Refer to Transmission Fluid Replacement .
Did you find and repair the condition?		 Go to Step 24  Go to Step 11 
11  Inspect the shift tower boot.
Is the closeout boot loose or damaged?		 Go to Step 12  Go to Step 13 
12 Position and tighten the shift tower boot to specifications. Refer to Fastener Tightening Specifications .
Did you find and repair the condition?		 Go to Step 24  Go to Step 13 
13 Is the vehicle equipped with a power take off (PTO)? Go to Step 14  Go to Step 17 
14 Remove the PTO in order to confirm that the PTO is not the cause of the noise.
Is the noise still present?		 Go to Step 17  Go to Step 15 
15 Inspect the countershaft gear for damage from the PTO.
Is the countershaft gear damaged?		 Go to Step 23  Go to Step 16 
16 Install the PTO. Ensure it is properly shimmed. Refer to the PTO manufactures installation procedure.
Is the noise still present?		 Go to Step 17  Go to Step 24 
17 Is the vehicle equipped with a transfer case? Go to Step 18  Go to Step 19 
18 Engage the transfer case in the different modes.
Is the noise still present or the same?		 Go to Step 19  Go to Symptoms - Transfer Case in Transfer Case NVG 246-NP8 or Symptoms - Transfer Case in Transfer Case NVG 261-NP2
19
  1. Inspect for engine to transmission alignment.
  2. Inspect for loose transmission mounting bolts.
Are there any loose transmission mounting bolts?		 Go to Step 20  Go to Step 21 
20 Replace and tighten the transmission mounting bolts. Refer to Transmission Mount Replacement .
Is the noise still present?		 Go to Step 21  Go to Step 24 
21  With the engine operating, depress the clutch pedal.
Is the noise still present?		 Go to Step 22  Go to Step 23 
22
  1. Remove the clutch. Refer to Clutch Assembly Replacement in Clutch.
  2. Inspect the following components for being the cause of the noise.
    • The release bearing
    • The pilot bearing
    • The dual mass flywheel, if equipped
    • The pressure plate
    • The clutch disc
    • The input shaft bearing
    • The engine crankshaft end play
Did you find and repair the condition?		 Go to Step 24  Go to Step 23 
23
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Disassemble the transmission. Refer to Transmission Disassemble in Manual Transmission - ZF S6-650 Unit Repair. Use the information in the Cleaning and Inspection section to determine if any of the transmission components are faulty.
Did you find and repair the condition?		 Go to Step 24  -
24 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 1 
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