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I need info on how to change the pinion seal on the differential of an 83 F100 with 9" rear (3.5 ratio). Any info or directions would help. Leaks really bad @ the flange. Thanks
Are you talking about the pinion carrier or the actual pinion seal?
The pinion seal is fairly straight forward. You'll need to disconnect the driveshaft and the flange (use a long breaker bar or a good air wrench on the pinion nut)
After the nut is off everything can then come apart and take not where they go back.
Drive the seal out with a punch and then lightly tap the new seal into place. Tapping evenly around it.
Put it back together with a new gasket on the carrier.
Forgive my ignorance but is the carrier the gray nylon plastic seal that covers the seal? The reason I ask is that I've got a 91 F-150 and the differential is leaking at the pinion. I replaced the seal and the leak continued so I thought that I had messed up the seal installing it and replaced it again. Guess what, it still leaks. That little gray plastic thing that fits over the seal appears worn though but I thought that it was nothing more than a dust cover. Is this integral to the sealing of the differential?
Have seen rears leak thru the spline for the yoke. Remove yoke, clean splines on pinion and yoke, apply small bead of silicone on pinion shaft, small bead on yoke spline, reassemble using torque spec on pinion nut. This should seal any chance of a leak past splines, unless splines are whipped. Don't retighten pinion nut with impact wrench, this will brinell the bearings in the pinion, (been there, done that)use a large ratchet/breaker bar, tighten until no end play on pinion is evident, then give 'er a good tug more. You should be able to feel when you come up against the crush sleeve. Pinion should have a slight drag when turned thru the backlash. If it freewheels it is too loose. If it is too tight, you will know in short order. Things will get hot, or howl, or tear up the gears. Now you have to tear it down for a rebuild. Get a service manual and find as much info as possible before you start if you haven't done this before. Good luck.
If you have a pinion seal leak the first thing that should be inspected is the vent for blockage . If the vent is clogged the pinion seal is the next easiest way for the pressure to release . Most of the time cleaning a blocked vent tube will stop a pinion seal leak .