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Rear differental seal leaking after fluid change?

Chris-1997

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I just changed my rear differental fluid I took it for a spin and when I got home the differental cover wasn't leaking neither was the fill plug but it was actually the pinion seal or what looks to be. My first thought was the breather tube was clogged so I took it off and tried to put some water through it and nothing happened so I cranked up the water pressure and something shot out the end of the tube so I assumed that all of that pressure was causing it to get pushed out the seal. But I was wrong I just took it for another ride after cooling off for some time and the same thing happened it's still coming from the pinion seal and quite a lot (see photos) and only seams to happen when I stop I looked down my longish Drive was with no drops to be found. Do I have a faulty breather valve that isn't opening? Or the seal just happened to go bad? I also have a rear end whine that I've had for months when going faster that 30mph is it a bad bearing? The leaks that you are seeing are after about 3 minutes of being in park and then it stops leaking.

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koda2000

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There is no valve. Just the vent hose. It looks like you have a toasted pinion seal. If you had whining before the fluid change, it's unlikely that changing the fluid is going to help.
 




Chris-1997

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There is no valve. Just the vent hose. It looks like you have a toasted pinion seal. If you had whining before the fluid change, it's unlikely that changing the fluid is going to help.
I did a little more investigating and found that when the tube was blocked the pressure was so strong that it actually started to push the seal out and it's not flush inside of the housing anymore and if the flange wasn't there if would have just shot out so I went ahead and ordered a new seal and pinion nut
 




koda2000

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It's not that simple to replace the pinion seal. That's because there is a crush sleeve behind the yoke and the nut has to be tightened until the right amount on drag is put on the pinion and ring gears. One way to do this without replacing the crush sleeve is to mark the pinion nut with a punch and to make a corresponding alignment mark on the differential housing. Then after replacing the seal and yoke, re-tighten the nut so that marks match up.

As your diff already whines, things are maybe not so critical in your case, but I would not replace the old nut, because you'll have no idea how tight to make the new one.
 




Chris-1997

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It's not that simple to replace the pinion seal. That's because there is a crush sleeve behind the yoke and the nut has to be tightened until the right amount on drag is put on the pinion and ring gears. One way to do this without replacing the crush sleeve is to mark the pinion nut with a punch and to make a corresponding alignment mark on the differential housing. Then after replacing the seal and yoke, re-tighten the nut so that marks match up.

As your diff already whines, things are maybe not so critical in your case, but I would not replace the old nut, because you'll have no idea how tight to make the new one.
Yeah there seems to always be a big debate on if you should replace the pinion nut so I thought I might as well it's only a few extra bucks but then you bring up a good point on being able to put the correct bearing preload so I will just stick to the old nut and mark it and count how many threads are showing. Any more tips?
 




koda2000

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Yeah there seems to always be a big debate on if you should replace the pinion nut so I thought I might as well it's only a few extra bucks but then you bring up a good point on being able to put the correct bearing preload so I will just stick to the old nut and mark it and count how many threads are showing. Any more tips?

No other tips, but curious. Are you working under the truck in you garage/driveway? The reason I ask is I'm wondering how you plan to get the nut loose w/out having the wheels turn on you? Hope you have a good parking brake and an impact wrench, because the nut may be quite tight and it's hard to get any leverage with hand tools with the rear wheels still on the ground. If you've got a helper, they could stand on the brake pedal (engine running for power assist) so you could have the rear wheels off the ground with no chance of them turning.
 




Chris-1997

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No other tips, but curious. Are you working under the truck in you garage/driveway? The reason I ask is I'm wondering how you plan to get the nut loose w/out having the wheels turn on you? Hope you have a good parking brake and an impact wrench, because the nut may be quite tight and it's hard to get any leverage with hand tools with the rear wheels still on the ground. If you've got a helper, they could stand on the brake pedal (engine running for power assist) so you could have the rear wheels off the ground with not chance of them turning.
No unfortunately I have one of the shittiest driveways it has a somewhat bad slope to it and my garage is small but flat so I can only fit about half of my vehicle in it what I have to do is back my car in the garage then drive the front wheels on ramps lock the e brake and use chocks and the ramps make my car level then there is enough room for me to get under there. It might be hard to imagine but basically the front of the car is on ramps then there is a good gap between the car and the floor because of the slope it's not by any means easy to do stuff but it gives me a good about of room.
 




CDW6212R

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I've replaced two pinion seals without altering the crush sleeve etc, one on front and on in the back. I forgot how I held the rear when I did that about 17 years ago, that was my 91 Lincoln. I did the front of my 99 Explorer in 2005, and that wasn't too hard to do with the tires on the ground.

Mark the pinion nut, and the pinion shaft end itself, that's what needs to be exactly the same when it's done. I did that and both of mine have been fine since then.

There is some wear over years of time, so in theory the nut could be made just a hair tighter to take up wear slack(which is where the noises come from). Mine didn't make any noises beforehand, the seals were just leaking a bit.

The right way to do it is with all new parts of course, the nut, crush sleeve, all bearings etc. But that's what takes an experienced professional, and a lot more money. Do it right if you can, but in a pinch you can probably change just the seal, using all of the other used parts.
 




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