Scott Osborne

I know there has been some posting on this but I wanted to start my own thread just to see if anyone could help. I have a 1999 Tacoma 2.7L 4WD 240,000. Recently, the connection of the drive shaft and rear differential started leaking so I went ahead and replaced the rear pinion seal with a duralast seal. When I removed the pinion nut I did all the marking for its alignment and tightened it back up to spec after I put the new seal in. Everything seemed fine, however the darn thing is still slinging gear oil all over the bottom of the truck and is still leaking. Anyone have any thoughts? I'm no expert here, but I can do simple repairs.

BTW - when I removed the old seal there were pieces of it stuck to the metal plate that I had to lightly sand off and the plate showed a light level of rust buildup. Any and all help is appreciated.

TacoTank

Are you sure the leak isn't at the end where the driveshaft meets the axle? When I hit 220K I had the same problem, oil slinging all over the place. Thought it was the one you replaced but ended up being the one at the axle hub. Diff fluid covered the whole thing so it was hard to tell at first.

Scott Osborne

I can see a light drip form after I wipe it clean from directly below where the seal is compressed behind the flange. It doesnt seem to be leaking from the surface where the driveshaft connects to the entire rear axle assembly etc. that is connected by 4 bolts. When I installed the seal I was not able to "insert" the entire seal into a depression where I would tap it in with a hammer like Ive seen in other tutorials. Essentially the inner ring went through the hole around the pinion shaft and the concave side sat against a metal ring around the pinion shaft and compressed with the "flat" side of the seal facing towards the front of the vehicle. Im pretty sure that is the correct orientation of the seal, however I was a little confused to find a flat surface that I had to compress the seal against.

Ive heard of other people cleaning out their diffuser b/c pressure was too high. Where is the diffuser located?

Thank you

TacoTank

Honestly never heard of a diffuser...breather maybe?
Im thinking two things here. Did you possibly sand off too much from the plate, therefore not being able to make a good seal? Also, did you lubricate the seal? If you don't it can tear when inserted.

Scott Osborne

Yeah I mean the breather…I haven't messed with that before. I don't think I sanded too much off b/c I had to remove the stuck on debris from the previous seal that were stuck on the plate. Plus there was a bit of rust built up that was inhibiting the lip of the flange from creating a good seal. I did also lubricate it. It seemed bizarre that the seal was shaped like this: (drive train) ===I I> (pinion ring) [ (shape of seal against flat plate around pinion shaft) My guess is that Im going to have to get someone to take a look at it. Truck runs well, but the oil is spitting all over during operation and has a slow leak when it is parked. Im pretty sure I oriented the seal correctly from all I read and saw in tutorials, however unless the ( [ ) shape pressing against a flat plate did not spread out and seal correctly. I remember when I was tightening the pinion nut down I had to really crank on it a lot to get it to compress the seal.

I wonder was the metal plate around the pinion shaft part of the old seal that somehow rusted in there? I couldn't see any sort of gap around the ring and didn't know if some seals were manufactured as a metal ring with rubber inner. All of the videos that I saw showed the person inserting the entire seal into a ring around the pinion shaft, not compressing a new seal against an already existing plate surrounding the pinion shaft. It just didn't seem removable.

TacoTank

I've never had to work with the breather but you may want to see if it's clogged. Mine (as well as yours) should be top of the axle hub, driver's side.