pinion shaft seal

I may have to replace the pinion shaft seal on my dana 25 (57 cj5). I already had the powerlocks installed at a 4wd specialty shop and they said the pinion shaft seal was replaced at that time. There is oil dripping from the bottom of the diff and I think it may be the shaft seal again. I was doing some research and noticed some diffs have a vent. IS this true of all diffs? If so, could a clogged up vent be the cause of the leak? Where would I find the ent on my 44 and 25?

I searched some videos and noted a couple of mechanics saying to draw a line on the shaft/nut/yoke to ensure they line up after replacing the seal to ensure proper preload. Also, they mentioned counting the turns it takes to get the nut off then reapplying it with the same amount of turns. Does that information hold true for old jeep diffs?

Never tackled this repair and I don't want to mess it up.

Thanks,
Paul

 

Did they mention how the seal surface on the yoke was? If it was chewed up, it'll eat up a new seal.

IIRC, both my 25 and 44 have a small hole on top of the tube for a vent.

The other stuff I'll defer to others with more experience than I.

 

The Dana 25 has a vent on the cover, which is a little elbow tube with a cap on it coming out of the top of the cover. The 44 has a small pin-sized vent hole on the long side of the axle housing tube and two small vents at the hubs near the grease zerks.

It is possible they did not replace your seal even though they said they did. Or maybe they installed it improperly (backward for example.) Replacing a seal is not hard, just be sure to torque your yoke nut to specs -- or at least count the number of turns as you mentioned.

Just yank the old one out, clean the surface, and carefully hammer the new one in using a rubber mallet and/or a block of wood. It wouldn't hurt to smear some gasket sealant on the outside of the seal.

 

Are the vent holes supposed to be capped or open all the time to atmosphere? Are they supposed to have a hose attached for venting?

 

The Dana 25 has the elbow vent on the cover and it is capped with a breather cap and a piece of felt down inside to keep out debris. There is no hose unless you want to add one for fording.

The Dana 44 vent holes are just holes with no caps and no filter. I have no idea why, it doesn't seem like the best design to me.

 

Don't just count the turns of the nut. USE A TORQUE WRENCH and torque the nut properly. I'd also suggest some thread locker on the nut so it doesn't work loose. Gears are too expensive to rely on (count the turns) method of torquing. Also, while you have the yoke off check the seal surface very carefully for pits or grooves. Any damage where the seal rides can eat up the seal in short order. It's possible the garter spring popped off when they installed the seal. I put a little grease behind it to keep it in place. I also put some sealer on the splines of the yoke. As it's installed the sealer "smears" inside the splines and helps keep leaks from happening there as well.

 

What Nick said. Torque the nut to 215 -220 ft-lbs.

I found 1/8 NPT barbs and screwed them into my D44 axle vent hole that was located on the driver side axle tube (top). Then ran some rubber tubing up high and put another pipe barb in, then screwed in these vents I found at Grainger for around $1.30 each.

 

so basically there is 1 nut holding the yoke and seal in. Don't worry about the turns, torque it to 215-220 ft-lbs. Do the front hubs need to be locked in to remove the bearing and yoke? Is there a torque for the u-joint bolts?

Brad, can you send me links to the parts you mentioned for making the vents?
Nickmil, is that permatex #2 for the sealer?

What type of sealant on the outside of the oil seal? Any RTV?

Thanks,

 

I use RTV Ultra Black or Permatex "The Right Stuff". I don't like Permatex #2 for the sealer. Too hard to get stuff apart later and even though it's supposed to be non hardening, it does. Make sure all parts are clean and oil free where sealer is used. Make sure there is a small amount of lube on the lip of the seal so it isn't run dry. My FSM shows 200-220 lbs. ft. for the yoke nut. Don't know what bearing you are talking about but shouldn't need to remove one to replace the pinion seal. Having the hubs locked in can help to hold the yoke from turning.
I'd highly recommend purchasing a Factory or Technical Service Manual if you plan on keeping this Jeep and working on it. Lots of very important step by step info as well as torque specs.

 

Sorry, I meant the seal, not bearing. Where to get a factory/technical service manual (is there a difference in the two?)?

 

Does anyone know the part number for the pinion shaft seal?

 

Not off the top of my head but they are the same seal for Dana 25,27,30,and 44
Any parts store should have them or be able to get them
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is this gear oil the right kind? It says Napa Premium performance gear oil. SAE 80w-85w-90. Before I use it. Got the seal today. Thanks,
Paul

http://www.napaonline.com/Search/Detail.aspx?R=NO_75210_0006411584

The manual specifies SAE 80 for the front and rear diff with type being MIL-L-2105 B. Reading on here, everyone mentions 90 weight.