GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2008 🢒 I-370 🢒 Transmission/Transaxle 🢒 Manual Transmission - Aisin AR5 🢒 Transmission Fluid Leak Diagnosis

Diagnostic Aids

Using the incorrect type of transmission fluid may affect the sealing ability of the seals. Ensure the use of the correct type of transmission fluid. The incorrect type of sealer may not be compatible with the transmission fluid or may not have the correct characteristics for sealing the affected components. Ensure the use of the correct type of sealers. Refer to Adhesives, Fluids, Lubricants, and Sealers .

Test Description

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

  1. 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.

    2.

  2. With the 4WD application, the sealing surface, for the transmission rear seal, is on the transfer case input shaft.

    3.

  3. With the 4WD application, a weep hole is located at the transfer case to transmission flange. If fluid is leaking at the weep hole, verify if it is transmission fluid or transfer case fluid.

    4.

  4. Two bolts, for the clutch housing, require the use of sealer.

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 being higher than the recommended level. Refer to Transmission Fluid Replacement .
  2. Adjust the transmission level if incorrect.

Was the transmission fluid level too high?

Go to Step 31

Go to Step 3

3

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. Visually 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 4

Go to Step 5

4

Replace the drain or fill plug gasket. Refer to Transmission Fluid Replacement .

Did you find and repair the condition?

Go to Step 31

Go to Diagnostic Aids

5

Is the leak at the transmission output shaft seal?

Go to Step 6

Go to Step 7

6

Remove the output shaft seal and inspect for the following conditions. Refer to Transmission Housing Oil Seal Replacement - Rear .

    • Damaged or worn seal
    • Damaged seal bore
    • Improper installation
    • Cracks in the component
    • Propeller shaft yoke sealing surface is scratched, nicked, damaged, or worn
    • If 4WD, transfer case input shaft seal surface damaged
    • Loose or worn bearing causing excessive seal wear

Did you find and repair the condition?

Go to Step 31

Go to Diagnostic Aids

7

If 4WD, is the leak at the transfer case to transmission weep hole?

Go to Step 8

Go to Step 9

8
  1. Remove the transfer case. Refer to Transfer Case Assembly Replacement.
  2. Inspect the shift shaft plug for leaking.
  3. Replace the shift shaft plug if leaking. Refer to Transmission Disassemble and Transmission Assemble.

Did you find and repair the condition?

Go to Step 31

Go to Diagnostic Aids

9

Is the leak at the shift lever area?

Go to Step 10

Go to Step 11

10
  1. Inspect the shift control lever lower boot for damage.
  2. Inspect for loose shift control housing mounting bolts.
  3. Remove the shift control housing. Refer to Control Lever and/or Boot Replacement .
  4. Replace the shift control lever lower boot if damaged.
  5. Inspect the shift control lever sealing surfaces for scratched, nicked or damaged.

Did you find and repair the condition?

Go to Step 31

Go to Diagnostic Aids

11

Is the leak at the front of the transmission?

Go to Step 12

Go to Step 21

12
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Remove the clutch actuator cylinder. Refer to Clutch Actuator Cylinder Replacement.

Is the input shaft seal leaking?

Go to Step 13

Go to Step 14

13
  1. Inspect for the following conditions if the input shaft seal is leaking:
    2. • 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
  2. Replace the input shaft seal if leaking. Refer to Transmission Input Shaft Seal Replacement .

Did you find and repair the condition?

Go to Step 31

Go to Step 14

14

Inspect the shift rail plug for leaking.

Is the transmission leaking at the shift rail plug?

Go to Step 15

Go to Step 16

15

Replace the shift rail plug. Refer to Transmission Disassemble and Transmission Assemble.

Did you find and repair the condition?

Go to Step 31

Go to Step 1

16

Inspect for leaking at the front retainer bolts.

Is the transmission leaking at the front retainer bolts?

Go to Step 17

Go to Step 18

17

Remove the leaking front retainer bolts and install with the proper sealer. Refer to Transmission Disassemble and Transmission Assemble.

Did you find and repair the condition?

Go to Step 31

Go to Step 1

18

Inspect for leaking at the clutch housing bolts.

Is the transmission leaking at the clutch housing bolts?

Go to Step 19

Go to Step 20

19

Remove the leaking clutch housing bolts and install with the proper sealer. Refer to Transmission Disassemble and Transmission Assemble.

Did you find and repair the condition?

Go to Step 31

Go to Step 20

20
  1. Inspect the case for cracks or porosity.
  2. Replace the transmission front case half if it is faulty. Refer to Transmission Disassemble .

Did you find and repair the condition?

Go to Step 31

Go to Diagnostic Aids

21

Is the leak at the vehicle speed sensor (VSS)?

Go to Step 22

Go to Step 23

22
  1. Remove the VSS. Refer to Vehicle Speed Sensor Replacement .
  2. Inspect for the following conditions:
    3. • Cut or damaged O-ring seal
    • VSS over tightened causing deformation in the VSS
    • VSS bore scratched or damaged

Did you find and repair the condition?

Go to Step 31

Go to Step 1

23

Is the leak at the backup lamp switch?

Go to Step 24

Go to Step 25

24
  1. Remove the backup lamp switch. Refer to Backup Lamp Switch Replacement .
  2. Inspect for the following conditions:
    3. • Cross threaded or damaged threads
    • Insufficient sealant
    • Leaking switch
    • Improper installation

Did you find and repair the condition?

Go to Step 31

Go to Step 1

25

Is the leak at the shift shaft detent plugs?

Go to Step 26

Go to Step 27

26
  1. Remove the shift shaft detent plugs. Refer to Transmission Disassemble and Transmission Assemble.
  2. Inspect for the following conditions:
    3. • Cross threaded or damaged threads
    • Insufficient sealant
    • Cracked case
    • Improper installation

Did you find and repair the condition?

Go to Step 31

Go to Step 1

27

Is the leak at the sealing flanges of the transmission cases?

Go to Step 28

Go to Step 29

28
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Disassemble the transmission. Refer to Transmission Disassemble.
  3. Inspect the sealing surfaces. Refer to Transmission Case Cleaning and Inspection.

Did you find and repair the condition?

Go to Step 31

Go to Step 29

29

Is the leak coming from a crack or porosity in the transmission case?

Go to Step 30

Go to Diagnostic Aids

30
  1. Remove the transmission. Refer to Transmission Replacement .
  2. Disassemble the transmission. Refer to Transmission Disassemble.
  3. Replace the faulty case. Refer to Transmission Extension Assemble or Transmission Case Assemble or Transmission Assemble.

Did you find and repair the condition?

Go to Step 31

Go to Diagnostic Aids

31

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 1