Pinion seal question

[Frankenchevy]

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Took my first long, hot drive yesterday. I noticed some oil in a radial pattern on the underside of the bed this morning. I know it happened yesterday and hasn’t happened before because I’m a weirdo and look under the truck every time I drive it. I took off the vent tube and it’s clogged, so I think that was the issue. If not, I’ll change the pinion seal.

What is the likelihood of built up pressure causing this? Also, what is the likelihood of the pinion seal having been damaged by the pressures?

 

[bucket]

I would think a plugged vent could easily cause that. I don't think it would hurt the seal though. If it is simply the seal leaking, it would have done it without the help of the plugged vent.

 

[yevgenievich]

Agree on the vent

 

[Frankenchevy]

Replaced the vent and check valve. Drove this morning. Had a little spray, but may have been residual inside the collar thing. If not, it seems a seal replacement is in my future.

If the seal had failed from anything other than age, what would it be? I don’t have any odd noises, gear mesh in the rear looked okay.

Maybe pinion play? There is a definite clunk when going from Drive to Reverse and back, but it doesn’t seem abnormal. Th400/208/14ff, if any of that makes a difference in one’s opinion.

Should I have my wife shift from D to R and back and observe approximate degrees of rotation I get on the driveshaft?

Lastly, I started another thread about this and maybe should have just asked it here—what are you guys replacing the fill plugs with? Mine looks okay, but makes me scared. Looks like someone used a 3/8 driver or extension that had roundish corners. Appears to be 1/2”NPT...

 

[Blue Ox]

The clunk usually has to do with backlash rather than pinion bearings. Put it in neutral and see if the pinion has any side to side or axial play as opposed to when turning.

Enough pressure could invert the seal lip, but it would take some pretty significant pressure. I'd clean it with Brakekleen and compressed air and try driving it again before you condemn it.

 

[QBuff02]

Just replaced the pinion seal in my 14bff two weekends ago, it had a little residual oil about the area and then might leave a couple drips after I parked it until it literally one day puked it out everywhere under the truck just like in your picture. When I replaced it, the rubber part of the seal was dry rotted and brittle and had separated from the metal ring of the seal, literally it fell apart when I took it out of the axle. Vent was clean and clear on mine, just think the pinion seal finally fell victim to the 4 years the truck sat in a barn before I bought it. Mine has the standard clunk going from forward to reverse but nothing too crazy and the pinion and bearings were tight. cleaned it up, slapped the new seal in, put it back together and have put about 150 miles on it since doing so without an issue or a single drop of oil. But maybe you'll get lucky and it was just the vent clogged up. However, if it built up enough pressure to push oil past the seal it's likely the seal is going to be south of cheese also.

 

[Frankenchevy]

Glad I've been driving this more often to shake the bugs out before camping and hunting for the rest of the season.

the pinion seal definitely needed replacing. I ordered a Timken 2286. wont have it till Tuesday. so it'll rest til then.

any quick advice/recommendations? I planned on marking the nut and threads then counting threads. anything else to do once I have the marks lined back up such as specific torque values?

 

[QBuff02]

Glad I've been driving this more often to shake the bugs out before camping and hunting for the rest of the season.

the pinion seal definitely needed replacing. I ordered a Timken 2286. wont have it till Tuesday. so it'll rest til then.

any quick advice/recommendations? I planned on marking the nut and threads then counting threads. anything else to do once I have the marks lined back up such as specific torque values?

I cleaned everything off real good before I took it apart. wire brushed the pinion nut and yoke and cleaned it off with some starting fluid and then I used a paint pen to mark the end of the pinion and the nut and used a small center punch to mark their locations in the paint for easier reference. I counted the threads and removed it all and replaced the seal, when I went back together I put it all back in the same locations/amount of threads and then went just a hair past my witness marks being lined up and called it good. The only other thing I did since I had the driveshaft out was I also opted to replace the output seal on the transfer case since all the labor was already done to get there.

 

[Frankenchevy]

Have you guys seen where people use rtv between the seal ring / diff case and yoke/splines?

 

[Frankenchevy]

Doing the u joints as well. I pressed the caps in far enough for the clips to seat. Now the u joint feels tight. It’s smooth in operation so no bearing out of place. I tried pulling the clips and whacking the perpendicular caps to try to push them apart a bit, but didn’t produce much with the force I was willing to whack the bearing cap with.

This normal? Should I press it out and start again?

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[Frankenchevy]

New pinion seal in. Just waiting on above advice before putting it all back together.

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Edit: I watched a video series on u joints and axial play. There are different thickness clips that change axial play. Preload isn’t what you want .001-.002 is ... I take that as it means it doesn’t feel like it moves axially, but rotates easily..

 

[Blue Ox]

I can't say I've ever seen different thickness clips, but if they say so.

When installing U-joints I usually just press the cap back against the clip once I have it installed.

Another thing to note is to position the cross so the zerk is under compression when the shaft is driving the truck forward. Which it appears you did.

 

[Frankenchevy]

I can't say I've ever seen different thickness clips, but if they say so.

When installing U-joints I usually just press the cap back against the clip once I have it installed.

Another thing to note is to position the cross so the zerk is under compression when the shaft is driving the truck forward. Which it appears you did.

I guess there are 6 or 7 different thickness lock ring clips for steel yokes. The ones that came with my spicer joints are the brass colored ones, which are third thinnest. Flat steel color being second and purple are the thinnest.

 

[Blue Ox]

Interesting. Never had a need for such a thing before. But good to know.

 

[78C10BigTen]

Ok so all the talk of pinion seals i hear is of the 14 bolt kind. I have a 10 bolt in my truck and it recently started puking fluid all over. Even stationary it drips right out, can anyone tell me what is involved in fixing this problem? Also does it look like the pinion is separating from the rear, is this possible? Im kinda lost here

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