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14BFF leaking near pinion

Mastiff

Mastiff

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I've been reading loads of threads about this. It appears I've sprung a leak somewhere near the pinion on my rear diff. I have a DIY4x pinion guard on there, so it's hard to tell exactly where the leak is. Is it almost certainly the pinion seal, or is it possible to leak from the bolts holding the whole pinion in (which I changed when installing the pinion guard), or from the pinion assembly mounting surface (steel gasket in there?)?

From what I gather, I can undo the 4 bolts holding the pinion assembly on and pull the whole thing out to work on it. The 4 bolt mounting itself is not super critical. Is that right? Once I have it out, I think I can either do a hack job by marking it before disassembly and putting it back the same way, or else hire a professional to redo the crush sleeve. Do I have this right? Opinions on the DIY approach?
 
Mastiff said:
I've been reading loads of threads about this. It appears I've sprung a leak somewhere near the pinion on my rear diff. I have a DIY4x pinion guard on there, so it's hard to tell exactly where the leak is. Is it almost certainly the pinion seal, or is it possible to leak from the bolts holding the whole pinion in (which I changed when installing the pinion guard), or from the pinion assembly mounting surface (steel gasket in there?)?

From what I gather, I can undo the 4 bolts holding the pinion assembly on and pull the whole thing out to work on it. The 4 bolt mounting itself is not super critical. Is that right? Once I have it out, I think I can either do a hack job by marking it before disassembly and putting it back the same way, or else hire a professional to redo the crush sleeve. Do I have this right? Opinions on the DIY approach?
Click to expand...

It's usually always the pinion seal. Fairly easy to do. You can get a seal puller from any auto store...they look like an ice pick...pretty cheap to buy.

You want to start by pulling the yoke off the axle...mark the nut that's in the middle of that with a sharpie or paint. It's some where in 250ish ft lb range...

Once you have that off you can pull the seal. Make sure to clean the surface of course and put the seal in the right way! They usually have a spring that's visible and that always goes inward. Helps to put a bit of grease around the whole thing so you're not driving it in dry. I have a 2x4 that has a 2 inch hole in it just to drive seals in...don't want to get it off kilter.

Once that's in you can put the yoke back on and the pinion nut. Get it back to where it was and give it a tiny smidge more of a turn...that's the shade tree way of keeping the crush in check. There's such a thing as crush sleeve eliminator but that's a whole other can of worms.
 
Do you recommend doing it all on the truck, or pulling out the pinion assembly?
 
Mastiff said:
Do you recommend doing it all on the truck, or pulling out the pinion assembly?
Click to expand...

I think it depends on your tool availability. If you have an impact gun big enough to get that nut off then you could pull the whole thing out, put it in a vise and work on it. Before I had an impact gun I would have to do it on the ground with a pipe wrench on the yoke to get it off.

I don't see a huge benefit from
taking the whole unit out unless you have to work out in the dirt.
 
Thanks. I need to first convince myself it's the seal. The pinion guard came with bolts that were too long (bottoming out). I spaced them with washers, but maybe the whole pinion assembly still isn't snugged enough and it's leaking there. It's unlikely, but I should confirm before I do a bunch of work.
 
Mastiff said:
Thanks. I need to first convince myself it's the seal. The pinion guard came with bolts that were too long (bottoming out). I spaced them with washers, but maybe the whole pinion assembly still isn't snugged enough and it's leaking there. It's unlikely, but I should confirm before I do a bunch of work.
Click to expand...

I ran into a similar problem...definitely knock that off the list first.
 
Well, I got in there and pulled the pinion guard off, and it sure looks to me like the leak is from the mating surface for the whole pinion assembly, not the pinion itself. I was surprised that when I had all the bolts out, the assembly pulled back 1/16" of an inch or more all on it's own. So I've definitely opened up that seal while messing with this pinion guard. It's possible I didn't have it tight enough before, since the bolts were close to bottoming out. I installed it with shorter bolts this time. I'll keep an eye on it and see what happens next. It looks like it's just a steel gasket in there though, right? Install should be as easy as disconnecting the driveshaft and pulling the pinion assembly out?
 
Mastiff said:
Well, I got in there and pulled the pinion guard off, and it sure looks to me like the leak is from the mating surface for the whole pinion assembly, not the pinion itself. I was surprised that when I had all the bolts out, the assembly pulled back 1/16" of an inch or more all on it's own. So I've definitely opened up that seal while messing with this pinion guard. It's possible I didn't have it tight enough before, since the bolts were close to bottoming out. I installed it with shorter bolts this time. I'll keep an eye on it and see what happens next. It looks like it's just a steel gasket in there though, right? Install should be as easy as disconnecting the driveshaft and pulling the pinion assembly out?
Click to expand...

Yeah that's all you have to do. Make sure to clean the gasket and mating surfaces...gas or acetone.

There's probably a torque spec for those bolts. I can't remember but it would be on the 14 bolt bible if you search that.
 
Anyone have a part # for the pinion _assembly_ seal? All I can find is the round pinion seal.
 
I don't think there is a seal...those are shims to set-up the gears. I looked at this thread wanting to see if people recommend putting a super thin layer of rtv on either side of the shim pack. They might seal up if properly torqued though.
 
Yeah, I've since learned this. My plan is to do just that and attempt to reseal the existing stuff by cleaning it up and putting a thin layer of sealer.
 
Pull the pinion support out, carefully clean and scuff the shims and two mating surfaces with some scotchbrite, wipe everything down with lacquer thinner then use a nice thin coat of right stuff on both sides of each shim and all the mating surfaces, install, and tighten the bolts up and let the right stuff cure for 24 hrs then check the bolts and make sure their still tight.
 
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