Differential Assembly: Testing and Inspection

Symptom Chart(s)

Symptom Chart: NVH

Diagnostics assume a certain skill level and knowledge of Ford-specific diagnostic practices. REFER to Diagnostic Methods Fundamentals and Basics for information regarding Ford-specific diagnostic practices.

Inspection and Verification

1. Verify the customer concern.

2. Visually inspect for obvious signs of mechanical damage. Visual Inspection Chart - Mechanical





3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4. If the cause is not visually evident, verify the symptom and REFER to Symptom Chart: NVH.

Driveshaft Center U-Joint (Universal-Joint) and CV (Constant Velocity) Joint Inspection

With the vehicle in NEUTRAL, position it on a hoist. REFER to Lifting Points . Rotate the driveshaft by hand. Check for rough operation or seizure of the U-Joint (Universal-Joint) or CV (Constant Velocity) joints. Install a new driveshaft if it shows signs of seizure, excessive wear or incorrect seating. REFER to Driveshaft .

Driveshaft Center Bearing

With the vehicle in NEUTRAL, position it on a hoist. REFER to Lifting Points . Rotate the driveshaft by hand. If the bearings show signs of roughness or are noisy, install a new driveshaft assembly. REFER to Driveshaft .

NOTE: NVH (Noise, Vibration, or Harshness) symptoms should be identified using the diagnostic tools that are available. For a list of these tools, an explanation of their uses and a glossary of common terms, REFER to Noise, Vibration and Harshness. Since it is possible any one of multiple systems may be the cause of a symptom, it may be necessary to use a process of elimination type of diagnostic approach to pinpoint the responsible system. If this is not the causal system for the symptom, REFER to Noise, Vibration and Harshness for the next likely system and continue diagnosis.

Symptom Chart














Analysis of Leakage

Clean up the leaking area enough to identify the exact source.

A plugged RDU (Rear Drive Unit) housing vent can cause excessive pinion seal lip wear due to internal pressure buildup.

Verify the RDU (Rear Drive Unit) lubricant level is even with the bottom of the fill hole.

Axle Vent

A plugged vent will cause excessive seal lip wear due to internal pressure buildup. If a leak occurs, check the vent. If the vent cannot be cleared, install a new vent.

Drive Pinion Seal

Leaks at the drive pinion seal originate from the following causes:
- Damaged seal
- Worn seal journal surface

Any damage to the seal bore (dings, dents, gouges or other imperfections) distorts the seal casing and allows leakage past the outer edge of the drive pinion seal.

The drive pinion seal can be torn, cut or gouged if it is not installed correctly. The spring that holds the drive pinion seal against the pinion flange may be knocked out and allow fluid to pass the lip.

Metal chips trapped at the sealing lip can cause oil leaks. These can cause a wear groove on the drive pinion flange and result in pinion seal wear.

When a seal leak occurs, install a new drive pinion seal and check the vent to make sure it is clean and free of foreign material.

A new drive pinion flange must be installed if any of these conditions exist.

Drive Pinion Nut

NOTICE: When installing shafts, do not allow splines to contact seals during installation or damage to the seals may occur.

Halfshaft pilot bearing housing seals are susceptible to the same types of damage as drive pinion seals if incorrectly installed. The seal bore must be clean and the lip handled carefully to avoid cutting or tearing it. The seal journal surface must be free of nicks, gouges and rough surface texture. REFER to Stub Shaft Seal .