I'm getting the rear axle pinion oil seal replaced tomorrow and a bit nervous about it. is there anything i should watch out for or be concerned with. how hard of a job is this and what do i need to know. the seal is leaking pretty bad and needs replaced.

Respectfully,

Volve
Salt Lake City, Utah

Hey, looks like I'm in the same boat with my wagon. As of recently, the rear has been leaking a good deal. Just wondering how much the repair cost you and if you've had any issues with it.

Thanks for any info you can provide me,

Mike

Let me preface this with the fact that I have done more of these over the years than I can remember. Important facts:

1) retorque to factory spec of 135 foot pounds
2) do the entire operation with hand tools, do not gun the pinion nut on and off with a 1/2" impact. You can shoot the drive shaft nuts and bolts out though.
3) use the factory tool or equivalent to pull the drive shaft flange from the differential if it does not simply slide out. Some slide out and some require the tool. DO NOT beat it out with a hammer!
4) IMPORTANT, when you install the new seal put a coating of white grease on the spring on the inside of the seal. These have been known to pop off when they get hammered back in and the grease will aide in retaining it.
5) use a brand new nut when you go back together
6) I recommend using the factory counterhold tool for breaking the nut loose and, more importantly, to hold the flange will final torque is acheived.
7) lastly if the seal is a stubborn bitch and won't come out, take a small chisel and punch it in between the extreme outer edge of the seal and where it mates to the housing. This will cause the tin seal to fold over and release it's death grip on the steel diff housing. If you do this for 180 degrees or more around the outer circumference of the seal the darn thing will just about fall out. Whereas I have seen techs absolutely destroy the old seal using the factory tool.
8) refill with 80w/90 weight, clean up as much of the mess that it made as you can, recheck all of your drain and fill plugs, and be done with it.

Mark

You get it replaced,check for leaks,why be nervous?

steve

why be nervous?

I'd be nervous, having read that the torque on the pinion shaft nut is critical on replacement.

The theory(?) is that the pinion bearing pre-load was originally set by crushing a spacer sleeve or something, with the high torque applied to the nut.

The concern is about replacing the nut too loose or too tight, thus screwing up the bearing pre-load, and possibly the whole rear end.

Maybe this is myth, but I'd be nervous too.

Time for the pros to weigh in here.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

I did this a while ago and the head tech at a Volvo place in Albany NY--who just happened to be standing me near the dealership's parts counter--said just re-use the old crushed sleeve, tighten it to the correct torque and that'll be right on. He said that new sleeves are a pain to torque correctly. Having replaced seals and pinion shaft bearings on two Volvos and gotten flawless service out of the rear ends for collectively 300K (and counting in one case--the other car is long gone, RIP), I have no worries that you'll make out fine.

Steve,
I'm glad to hear you've had 2 successes but I'd still be nervous about tightening the nut "to the correct torque". My (limited) understanding is that the bottom line objective is to have the correct bearing pre-load. I don't think this can be measured directly, but will result in a slight drag on the pinion flange when turning by hand. I've read/heard that this pre-load turning drag should take about 1.5 to 2.0 ft lbs of torque to overcome.

At some point (guessing here) it was found that XXX ft pounds on the nut would crush a new "pre-load sleeve" to length "Y", resulting in a bearing load causing "x" ft lbs to rotate the pinion flange.

My concern about using "XXX" ft pounds on the same (crushed) sleeve again, is that the sleeve will be crushed even more — and thus do too much of what was just right for bearing load the first time, (I'm also guessing that much/most of the initial XXX ft lb of torque went toward crushing the sleeve. But that's another guess.)

Anyway, I've only done one pinion seal (still OK after 100k miles), but I used the method that swede4 outlines below — marking and counting so the nut goes back exactly where it was when the crush sleeve was first installed.

Still wondering (and still looking for those motor mounts),

Bruce
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

You are correct about the crush sleeve. In theory it should be replaced any time the nut is loosened. However, let's be practical:
Mark the nut and the flange before loosening and and re-tighten the nut to EXACTLY the same mark. You can't go wrong then. Of course , this necessitates that you re-use the existing nut.