Thunderbird V8-4.6L VIN W (1997)
There may be a rear axle housing leak through small pockets in the metal. These pockets (casting leakage) are caused by gas bubbles in the casting
process, known technically as a porous condition or porosity.
Because there is a concern of changing the axle's Noise, Vibration, and Harshness (NVH) characteristics if disassembled to replace the differential
case, service is preferable. Seal the porous pocket with Devcon Aluminum Liquid F2 meeting Ford specification M3D35-A(E).
Welds/Seams
Most minor weld leaks can be corrected with Devcon Aluminum Liquid F2 or equivalent meeting Ford manufacturing standard M3D35-A(E). This
includes the puddle or fill welds that join the axle shaft tube to the rear axle housing on integral axles. They sometimes leak and can be sealed easily. If a
weld is broken, the rear axle housing must be replaced. The alignment is too critical for field service.
Axle Vent
NOTE: If rear axle housing vent cannot be cleared, it must be replaced.
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A plugged rear axle housing vent will cause excessive seal lip wear due to internal pressure buildup. When a leak occurs, check the rear axle
housing vent which is located near the top of the differential housing.
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Make sure the vent hose is not kinked. Remove the vent hose from the vent nipple and make sure the hose is clear of dirt or other foreign
materials.
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While hose is removed, pass a length of wire or small diameter Allen wrench in and out of the vent nipple to clean it of any dirt or foreign
materials. Install vent hose.
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Make sure axle lubricant is level with bottom of fill hole.
