Leaky rear main

[davidroberts]

After only a few short weeks of ownership my '82 65LS has started to pee on my garage floor (and anywhere else I stop).
The oil is definitely engine and coming down the back and dripping off the engine casting under the neutral switch.
I intend doing the job myself and I was wanting to know if there are any other parts that I should replace or check while the gearbox is out?

This is my first time so any tips are welcome!

[georgesgiralt]

Hello,
To remove the main seal, you need to pull the gearbox out, the flywheel with the clutch and have the tool to put it back on place.
Depending on your skill and tooling this is a walk park or a hell of a job.
But while you're at it and have dismantled that much of the bike, I would check the oil pump, too, replace the O-ring under it's cover and check the clutch also.
Remember to put something on the alternator rotor between the front cover and the crankshaft to prevent the thruster washer to fall out when the flywheel is removed. Other wise you would have to open the whole engine to get it back in...
Last but not least, you can remove the gearbox with the swing arm in the bike IF you advance the engine as far front as it will go. You have to uncouple the mufflers, carbs, air box and then sustain the engine on wood blocks, remove the two rods and pull if using the exhaust tubes ...

[nhmaf]

Yes, if going in there, DO get an oil pump cover seal as well as a new rear main seal and do both while in there.
+1 with George's suggestions and BE SURE TO block the rotor (a cutoff pice of Allen key will work) against the inside of the front engine cover!

I find it easier to remove the swingarm pivot pins and push the swingarm back, blocking up the rear tire against the front of the rear fender to keep it out of the way.  Engine stays bolted in place.    There is a writeup of taking things apart to replace the clutch (with pictures!) on my 1982 R65LS in the FAQ section that I wrote up sometime ago.  It till get you 90% of the way there..

[montmil]

You many require the "special tool" to install the new oil seal. Besides Mike's excellent FAQs article, do your due diligence with Snowbum for even more in-depth information.

Might as well consider inspecting and re-greasing the swing arm bearings. There's additional info on centering the swingarm and torquing the attach hardware. Sing out when you're ready.

Some owners reuse the U-joint attach bolts where other will tell you "new is best". Should you buy "new", be advised BMW supplies shorted bolts and states that the washers are no longer to be refitted. You might find a PO has been inside the rubber boot before.

And then there's the whole rubber accordion boot issue. Check yours for cracks and/or tears. New boots should be marked for proper orientation during install. Save your best profanity and coldest Fosters for getting the  [smiley=furious3.gif] boot back on.

Take your time and she'll be right, Mate.

[davidroberts]

Thank you gentlemen, I have ordered the oil pump seal as well and have decided that I may as well check the swing arm bearings and drive shaft too.
The level of backup here at this forum gives me the confidence to do almost anything on the bike, thanks.

[tvrla]

There are three seals - not two! You've named the REAR MAIN and the Oil PUMP o-ring, but left out the CRANKSHAFT (or in your case GUIDE RING) o-ring.

The guide ring can be a booger to get off without damaging it, but there is a trick. Let us know when you get to that point. But - that o-ring IS important and should be changed!

I like removing the mufflers and the rear engine mount bolt and tilting the rear of the engine up to remove the transmission. It's the easiest method I've found and really quick. The engine will balance on the front mount and hardly needs any support in the rear - especially with the transmission out.

One other thing - it's a good idea having a torque wrench to tighten the U-Joint bolts. Until I got one, I'd always used a long 10mm wrench and leaned on it as hard as I could. Now, with the torque wrench, it takes more force than I was applying before. Those bolts take a LOT of torque!