Hey guys got a question.. I notice some oil on my rear drivers side rim today. When I was looking underneath it seems to be coming from rear axle seal. Sure smells like gear oil. Also my front pinion seal is leaking on rear diff. It could be as simple as just bad seals but I have a bad feeling it's something worse. I have notice a notable hum when driving around the city, thought maybe just my tires. Anyone have some info on what could have caused both seals to go? I have no problem changing seals myself and tearing into it but I wanna know what I might be getting into.. Thanks in advance!


2002 f150 4.6l triton
Diff has numbers 5588 on it (3.55 gears 8.8"?)

 

If it's leaking, have you checked the oil level?

 

Oil was ok when I drained it. Seemed a little sludgy but no chunks or shavings in it. I changed the pinion seal, rear axle seal (and bearing since I was in there.) everything internally was good. Problem seems to be fixed for now. The vent tube was the problem. It was plugged solid and broke.

 

It's not that unusual for an axle seal to leak. My 2000 that I bought new starting leaking at the right side rear axle seal. The pinion seal was not leaking so I pulled the axle, inspected the axle bearing and replaced the seal. doing it myself, the only cost was for the seal (about $6 at the dealer) and the diff oil (about $50 at the dealer for the oil and friction modifier). It's easy to do. No special tools needed. You may be able to replace the pinion seal at the same time and retighten the pinion nut. Don't know how to advise you on that because usually when that nut is installed you are crushing the bearing loader sleeve and that takes a lot of torque. Do a search on this site. I believe this was discussed in a thread a while back.

Way back in the mid 70's I had a Ford stationwagon that had a leaking pinion seal and axle seal. But that diff was making a noise that sounded like bad tires. I tore it down and replaced the front pinion bearing, sleeve, and axle seal. Everything else was ok. It took about 400 ft lbs to crush the bearing sleeve.