Motor-oil collecting/leaking at bell-housing drain hole

[belgian_motobricker]

Hello there fellow-motobrickers,

This is my very first post on this forum so I apologize in advance if I come off like a total noob :p

So recently I was able to identify and fix/replace a leaking clutch arm boot, thanks to this thread: http://www.motobrick.com/index.php?topic=2883.0

A few weeks later I noticed there is also motor-oil (99.99% sure it isn't gearbox-oil like last time) leaking/collecting at the drain hole in the bell-housing. As mentioned in the previously linked thread, this leak must have something to do with the clutch. But since I am quite new to all this I would love to hear from you guys what I should do next to narrow down and fix the issue that's causing the leak. Maybe there already exists a good topic on fixing this type of oil-leak but I couldn't find it, so any links to a good thread are also very welcome 

I don't know if it's relevant but the bike we are talking about is a k100 from '86 or something and has now driven 95.000 km's.

Thanks in advance for your replies and enjoy the summer-time motobrick-riding  :clap:

[jay1622]

Short answer...

If it's coming from that weep hole? An easy fix is making sure you're not over-filled with motor oil. If you're good there the likely culprit is number 11 in the link below. It's basically a rear main seal in the shape of an o-ring.

http://www.realoem.com/bmw/enUS/showparts?id=0516-USA-10-1986-K589-BMW-K_100_LT_87_0506,0516_&diagId=21_0251

And, if you do end up going that far? You get to replace your friction plate (if it needs it) and lube your splines too!

[belgian_motobricker]

Here are pics of the "hole" and my oil level.. Did do an oil-change about 4 weeks ago and I can notice the oil level has already dropped a bit since then.




What do you think? thx!

[jay1622]

It may be an issue on my end, but I cannot see any pictures. (Edit... I can see them now)

Here is a good reference to see what you would be getting into if you chose to do it yourself...

http://www.k100.biz/pdf/OFF/K100_K75_2V_eng.pdf

And

http://service.tanga-moteurs.ro/data/BMW__k100%20%26%20k75%20Haynes%20Manual.pdf

Open this second link, go page 93... The lower diagram is yours... Part 17.

[belgian_motobricker]

managed to attach the pictures, problem was mine ;)

[Laitch]

What do you think? thx!

I think that picture of your oil sight glass doesn't mean much to some of us because we don't know where the level was after you did your oil change. Right now it's at a reasonable level. Mine is usually near or slightly above the halfway mark.

What you probably have occurring is a rear main seal leak. If it doesn't stop by itself, you'll need to remove the final drive, the swing arm, the transmission and the clutch pack to remove the clutch nut and replace the seal and o-ring. There is a possibility that you overfilled the engine and with enough frequent riding it will stop leaking—that's happened to a few others here, but don't count on it happening to you.

Click on the Home page button then type Rear Main Seal in the search box there. You'll find plenty of discussion to supplement what's in the repair manual in jay1622's link.

[belgian_motobricker]

Well my oil level used to be a bit higher, it was flirting with the lower side of the "red arc" almost.. I even had to drain a lil oil after the oil change because i had over-filled her at first.. So it MIGHT have been overfilled :p and in that case I'm lucky? Or do you guys think it's more likely it's the seal?

[jay1622]

Questions for you (I'm setting you up here, FYI)... Was it leaking before the oil change?! If not, how soon after the oil change did it start leaking? Did you change the oil & filter, or just the oil? Did you use the sight glass when you refilled the crankcase, or did you use a specified amount? Did you change the viscosity or type (Dino/Synthetic)? What was the condition of the motor at the time of the oil sight glass picture (running, off, cold, hot, off but recently run)?

There is a CHANCE you MAY have over filled it. Please answer each question I've posted and we may be able to get you sorted.

[cgdan]

If the worse comes to the worse and it is your main seal don't panic (I did). Its a time consuming but essentially doable job. I am half way through mine and (I can only work evenings) and so far (with much advice of this forum) its been going well.