Transfer Case Leak Diagnosis. Chevrolet Astro

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2003 🢒 Astro - 4WD 🢒 Driveline/Axle 🢒 Transfer Case - NVG 136-NP4 🢒 Transfer Case Leak Diagnosis

Cause

Correction

DEFINITION: A visible indication of an external fluid leak from the transfer case.

Review the Symptoms - Transfer Case and perform the necessary inspections.

Rear output shaft seal leaking

•	Replace the rear output shaft seal. Refer to Rear Output Shaft Seal Replacement .

•	Inspect the slip yoke seal surface for wear or pitting. Replace the slip yoke if the surface could cause leakage.

•	Inspect the rear bushing for wear. Replace the bushing if worn. Refer to Rear Output Shaft Seal Replacement .

Speed sensor leaking

Replace the O-ring seal on the speed sensor. Refer to Transfer Case Speed Sensor Replacement .

Front output shaft seal leaking

•	Replace the front output shaft seal. Refer to Front Output Shaft Seal Replacement .

•	Inspect the front output shaft seal journal for wear. Replace the front output shaft if worn.

•	Inspect the seal bore for damage. Replace the front case half if the seal bore is damaged.

Leaking at the vent tube

•	Inspect for the correct transfer case fluid level. Refer to Transfer Case Fluid Replacement .

•	Inspect the transmission fluid level. Refer to Transmission Fluid Check in Automatic Transmission - 4L60-E.

•	If the transmission fluid level is low and the transfer case level too high, replace the transfer case input shaft seal. Refer to Input Shaft Seal Replacement .

•	Inspect the input shaft seal surface for wear or damage.

•	Replace a damaged or broken vent and seal the vent tube with the correct sealer. Refer to Transfer Case Assemble in Transfer Case - NVG 136-NP4 Unit Repair.

Encoder motor area leak

•	Inspect the encoder motor insulator gasket for cracks. Replace the encoder motor if the insulator gasket is cracked. Refer to Transfer Case Motor/Encoder Replacement .

•	Inspect for a faulty actuator lever shaft bearing. Replace the control actuator lever shaft if the bearing or seal surface is faulty. Replace the bearing if faulty. Refer to Transfer Case Assemble in Transfer Case - NVG 136-NP4 Unit Repair.

Transfer case to transmission area leak

•	Inspect the input shaft seal for leaking. Replace the input shaft seal if faulty. Refer to Input Shaft Seal Replacement .

•	Inspect the input shaft seal surface for wear or damage.

•	Inspect the front case seal bore for damage.

•	Inspect for leaking at the input gear bore seal. Replace the front case half if bore seal is faulty. Refer to Transfer Case Assemble in Transfer Case - NVG 136-NP4 Unit Repair.

•	Inspect the transmission adapter gasket for leaking. Replace the transmission adapter gasket if faulty. Refer to Transfer Case Adapter Replacement .

Front case half to rear case half seam leak

Disassemble and seal the case halves. Refer to Transfer Case Assemble in Transfer Case - NVG 136-NP4 Unit Repair.