Differential Seal Keeps Leaking ...Changed 2x

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Apr 19, 2024 | 10:59 AM

jimgnj

Thread Starter

5th Wheeling

Joined: Mar 2020

Posts: 49

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Differential Seal Keeps Leaking ...Changed 2x

2004 F-150 Heritage...300,000 miles 4.2 V6. About 3 years ago the rear starting a slow drip. I had a local mechanic, who I really like and who is an school guy, change the rear seal. About one year later it leaked again. He sanded (smoothed down the shaft, new seal and this time a little sealant). Now one year later it's dripping again. Any idea why this is a recurring. I assume he bought local auto parts store seal...would an actual Ford seal be better? Thanks.

Apr 19, 2024 | 03:30 PM

BareBonesXL

Fleet Mechanic

Joined: Jun 2023

Posts: 1,369

Likes: 382

From: WA

I have not experienced it myself but I've seen that leaks can occur down the splines of the pinion flange and the pinion gear shaft. Down the grooves. People either put some sealant on the splines or on the washer under the nut. I think that you can tell by examining the actual leak point closely.

Apr 26, 2024 | 11:57 PM

superrangerman2002

Logistics Pro

Joined: Jul 2002

Posts: 4,821

Likes: 19

From: South Dakota

The vent line sounds like it’s plugged. It can be the hose, or the barb on the axel. When it’s plugged, the axel heats up and the pressure pushes oil out of the seals.

Sanding on the pinion seal flange only should be done if there are some burrs….but should be avoided. Likely with that many miles the flange has a wear ring from the seal and needs a sleeve to make a bigger sealing surface and a new seal.