Milan FWD L4-2.3L (2008)
Drive/Propeller Shafts, Bearings and Joints: Component Tests and General Diagnostics
Analysis of Leakage
Analysis of Leakage
Clean up the leaking area enough to identify the exact source.
A plugged rear drive unit (RDU) housing vent can cause excessive pinion seal lip wear due to internal pressure buildup.
Verify the RDU lubricant level is at least 3-5 mm (1/8-3/16 in) below 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:
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Damaged seal
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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
CAUTION: Install the drive pinion nut to the correct torque specifications or damage to the differential components may occur.
On some high-mileage vehicles, oil may leak through the threads of the drive pinion nut. This condition can be corrected by installing a new nut and
applying Threadlock(R) and sealer on the threads and nut face.
Differential Seals
CAUTION: 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.
Driveline Angle Measurement
VDriveline Angle Measurement
Special Tool(s)
NOTE: This procedure does not apply to constant velocity (CV) joints, flex couplers or double cardan joints that are used in some driveshafts. This
check is for single-cross and roller-style joints found in the driveshafts.
NOTE: Prior to checking driveline angularity, inspect the U-joints for correct operation.
