XJ XJ8 / XJR ( X308 ) 1997 - 2003

Differential Pinion Seal seapage

Old 01-09-2019, 11:31 PM
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Default Differential Pinion Seal seapage

Don't know why, but I've just been having back luck with the differential on this car. First, my original differential was making a lot of noise, probably because low oil and extreme gear temperature or lack of lubrication, causing some teeth to shear. I swapped it out for a used 78k mile diff. It was fine up until I put the pedal to the medal, and heard loud tapping right underneath the center of the car. I guess there was to much traction, power, and the center bearing bushing (replaced about 2 months ago) did not provide enough resistance to prevent the driveshaft from buckling. The u-joint seemed to have made contact with the surrounding wall of the undercarriage (see the scoring in the picture). This incident, I believe, caused the pinion seal to fail, and gear oil has been seeping out since then.

I wish I could keep the car, but can not afford to maintain it anymore, so I'm selling the car. I need to stop the seepage while it's in the process of being sold. Shop quoted me +$500, and don't want to invest in fixing it up (again). Does anyone know of a good quick fix? Also, has this happened to anyone else?

Buckling scoring

Pinion seal seepage
Old 01-10-2019, 09:31 AM
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I would FIRST check the breather assy on top of the diff housing.
14mm wrench and getting your hand in the tight place above the housing will remove it. Check to ensure it is not stuck closed causing pressure buildup.

I replaced a seal once (years ago) and the diff still leaked from the output shaft a few days later.

I pulled the shaft out and heard a 'hissing' so I knew the vent was plugged.
Replaced the vent assy and NO MORE LEAK!!

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205-03 pinion leak.pdf (42.1 KB, 8 views)
Old 01-10-2019, 09:48 AM
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When I replaced the diff a couple weeks back, I checked the vent and it was good and clean. I'll see if I can check it this weekend though.

I checked the pinion shaft nut as well, and it was tight and had not loosened.

Old 01-11-2019, 09:13 PM
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Initially, the Diff I ordered came completely empty, so I poured 2 quarts of 75w-140 synthetic gear oil while I had it out. Upon taking the fill plug out and leveling the car, oil came dripping out, but not a significant amount. I assumed I would have needed to top it off from the loss of oil. Is the fill point just to the level of the fill plug on the Diff? If that's the case, then would 2 quarts to fill an empty diff be too much?

I also unscrewed the vent and verified it wasn't blocked.

I applied some gasket sealer to the pinion seal, and will see if that works.
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