'84 300sd pinion seal
 

Hi all,

I was just made aware that the pinion seal on my differential is leaking. There is fluid on the front of the differential where the driveshaft enters. I couldn't find a DIY article on pinion seal replacement. How big a job is this? Are there any guides for the replacement?

Thanks,
Jack

Jack,

Its a big job, but can be done.

The nut is staked into a slot in the pinion and must be unstaked for removal. The pinion nut (123 353 00 72) and the pinion seal (022 997 99 47) are available for modest cost. You can uise a 1/2" drive 1-3/6" thinwall 12-point socket to remove the nut.

Pull the yoke with a 'Y' shaped harmonic balancer puller, like the ones you can rent at Autozone. Change the seal and heat the yoke on a hot plate and slide it on with gloves. Immediately start tightening the nut and finish drawing the yoke into place.

As soon as you feel the nut go solid, stop turning. Now, with an assistant holding the brakes, give the nut just a slight nudge until you feel it move, This will take a LOT of effort. At this position, you can re-stake the nut into the slot....Robert