During the last oil change, the tech was kind enough to let me look under the XJ6 for leaks, and it appears that the front pinion is leaking after 35 years and 60,000 miles. There was so much congealed grease on the diff that I couldn’t readily tell if the side plates were leaking too, so I hired a mobile detailing service to degrease and pressure wash the underside of the Jag, including the IRS and diff.
Will have to observe for a few days and see if it is pinion seal, side covers or both that are leaking.
With the optimistic assumption that it is just the pinion leaking, I asked two reputable shops how much they would charge to replace the pinion seal.
The first shop wanted 2.5hrs of labor plus parts. He said he’d measure the running torque before removing the yoke, install the seal then torque to spec and measure the running torque again.
The second shop does a lot of diff work and I’ve used them in the past for a rebuild of a Jag diff (not this car). He quoted me about an hour of labor plus parts. He said, however, it is usually a fool’s errand to replace the pinion bearing because the bearing is often worn or loose and it will take out the seal again in fairly short order. He’d do it without a guarantee of the work. He does a lot of Dana diffs, but just a handful of Jags (His recommendation was to pull the diff and rebuild it - $350 + plus parts)
The technique to successfully restore the preload with a seal change notwithstanding, what’s the success in stemming the leak with a pinion seal change? Is the one mechanic correct that the seal will be just a temporary fix, or does heat from the inboard brakes cook them till they leak and I can get by for another 60K miles with a pinion seal change?
I’m leaning towards having the pinion seal replaced for the hour labor plus parts and rolling the dice on having stopped the leak.