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Home >> Cadillac >> 2021 >> CT4 Sport, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 117 (Manual Transmission - TREMEC 6-Speed (Mg9) - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Transmission Fluid Leak Diagnosis >> Test Description

Test Description

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The number below refers to the step number on the diagnostic table.

  1. 5 

    Use an approved method to clean the transmission to ensure the leak location is correctly identified. If using a powder method or dye method, ensure the products are compatible with the transmission fluid.

Step Action Yes No
DEFINITION: Visible sign of the transmission fluid leaking from the transmission.
1 Did you review the Symptoms - Manual Transmission  and perform the necessary inspections? Go to Step 2  Go to Symptoms - Manual Transmission 
2
  1. Inspect for the transmission fluid level higher than the recommended level. Transmission Fluid Drain and Fill
  2. Adjust the transmission level if incorrect.
Was the transmission fluid level too high?		 Go to Step 19  Go to Step 3 
3 Inspect the transmission vent for a blockage.
Is the transmission vent blocked?		 Go to Step 4  Go to Step 5 
4 Repair or replace the transmission vent.
Did you find and repair the condition?		 Go to Step 19  Go to Step 5 
5  Verify the location of the leak.
  1. Clean the transmission assembly.
  2. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.
  3. Visual inspect or use the powder method or dye and black light method to locate the leak.

Is the leak occurring at the drain or fill plug?		 Go to Step 6  Go to Step 7 
6 Replace the drain or fill plug. Transmission Fluid Drain and Fill
Did you find and repair the condition?		 Go to Step 19  Go to Diagnostic Aids
7 Is the leak at the transmission output shaft seal? Go to Step 8  Go to Step 9 
8 Remove the output shaft seal and inspect for the following. Main Shaft Rear Seal Replacement
  • Damaged or worn seal
  • Damaged seal bore
  • Improper installation
  • Cracks in the component
  • Propeller shaft yoke sealing surface is scratched, nicked, damaged, or worn
  • Loose or worn bearing causing excessive seal wear
  • Yoke flange nut loose

Did you find and repair the condition?		 Go to Step 19  Go to Diagnostic Aids
9 Is the leak at the front of the transmission? Go to Step 10  Go to Step 12 
10
  1. Inspect for the leak at the input shaft seal.
  2. Inspect for the following if the input shaft seal is leaking:
    • Damaged or worn seal
    • Damaged seal bore
    • Improper installation
    • Cracks in the component
    • Input shaft sealing surface is scratched, nicked, damaged or worn
    • Loose or worn bearing causing excessive seal wear
  3. Replace the input shaft seal if leaking. Main Shaft Rear Seal Replacement
Did you find and repair the condition?		 Go to Step 19  Go to Step 11 
11
  1. Inspect the case for cracks or porosity.
  2. Replace the transmission front case half if it is faulty. Transmission Disassemble
Did you find and repair the condition?		 Go to Step 19  Go to Diagnostic Aids
12 Is the leak at the backup light switch? Go to Step 13  Go to Step 15 
13
  1. Remove the backup light switch.
  2. Inspect for the following:
    • Cross threaded or damaged threads
    • Insufficient sealant
    • Leaking switch, sensor or solenoid
    • Improper installation
Did you find and repair the condition?		 Go to Step 19  Go to Step 1 
14
  1. Remove the shift shaft detent sleeve. Refer to the applicable procedure:
  2. Inspect for the following:
    • Cross threaded or damaged threads
    • Insufficient sealant
    • Cracked sleeve or case
    • Improper installation
Did you find and repair the condition?		 Go to Step 19  Go to Step 1 
15 Is the leak at the sealing flanges of the transmission case? Go to Step 16  Go to Step 17 
16
  1. Remove the transmission. Manual Transmission Removal and Installation
  2. Disassemble the transmission. Transmission Disassemble
  3. Inspect the sealing surfaces.
Did you find and repair the condition?		 Go to Step 19  Go to Step 17 
17 Is the leak coming from a crack or porosity in the transmission case? Go to Step 18  Go to Diagnostic Aids
18
  1. Remove the transmission. Manual Transmission Removal and Installation
  2. Disassemble the transmission. Transmission Disassemble
  3. Replace the faulty case. Transmission Assemble
Did you find and repair the condition?		 Go to Step 19  Go to Diagnostic Aids
19 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 1 
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