Finding gear oil leak?

[GTman]

I have an oil leak that shows up around the drive shaft boot. I can't tell if it's the final drive or transmission that it's coming from. After 5,000 miles there's no detectable drop in the fluid level in either. Is there a dye I can get, maybe at an auto parts store, that would be safe to add to the rear drive?

 

The dealer told me if the rear drive is over filled by even an ounce it will push it out through the seal because it can't handle the extra volume. Anyone ever heard of this? I'm using 80w-90 Amsoil, should I try 75w-140?

 

I pulled some out with a syringe. It really was a little over full, about half way up the threads of the fill port. I'm coming up on oil change time and want to determine where the leak is before changing it. Also, before I'm out of warranty.

[ELP_JC]

The easiest way is to bust one of the black zip-ties on the rubber boot and it'll be immediately obvious (buy one long enough first ). And even if oil slightly flows out of the fill hole it's fine; it's not that critical, and any extra usually spews out of the top vent.

A real oil leak would have the bottom of your boot and final drive full of fluid. Another approach is to perfectly clean that area and watch it after your next long ride. And you're fine with the 80/90 stuff; that's what is called for, and what I'd use (I use 75/90 Mobil 1).

Keep us posted.

[GTman]

It's not as easy as I thought it would be to visually tell which end the oil is coming from. I previously loosened the boot. The way the 2 parts come together make it impossible to tell where the oil comes from. It's like one pipe being partially inserted into another. Because of limited sight (not mine) even with a light I can't tell if the oil is running the length of the shaft from the transmission or dripping from the end of the rear drive and then running down. You just can't see far enough up the tube. If it was engine oil it would be easier because there would be a dirty trail.

[GTman]

I found an oil dye at NAPA. The guys at Advance Auto just looked dumb when I asked for an oil dye. It's the deepest red color you'd ever see. It surprised me when I added it to rear drive and gave the wheel a spin to mix it up. The oil turned the color of pea soup and reminded me of something from the Exorcist. I have a ride planned for next Thursday. Hopefully it will be long enough to net me some results.

[Fasterpill]

Well, you all might think I'm nuts, but I just washed mine off after it built up a bit a couple thousand miles ago. I thought I'd have to keep it clean every so often, but it did stop showing up. My previous K12 had gone back in to the dealer for a warranty seal replacement after 20K or so, by the previous owner. But I figured if the fluid level isn't dropping, it's just a little ooze and my best remedy was soap and water and a rag.

 

Guess it's a throwback to my Harley days when I had to keep plywood under the bike to catch all the oil and save my concrete.

[GTman]

But I figured if the fluid level isn't dropping, it's just a little ooze and my best remedy was soap and water and a rag.

 

Guess it's a throwback to my Harley days when I had to keep plywood under the bike to catch all the oil and save my concrete.

 

That would be my view on it too if I was faced with the bill for replacing the seal. I've got 22,000 on it now. The leak became noticeable around 17,000. Some guys at the Rally in SD told me it was fairly common. Funny, I had 2 Harleys before the BMW and never had an oil leak. I figure I'll get my warranty fix and if it happens again I'll let it ride until it gets bad.

[ghaverkamp]

My previous K12 had gone back in to the dealer for a warranty seal replacement after 20K or so, by the previous owner.

 

Twice, in fact. Fortunately, both times it was in for other service. In the first case, at 18K, it was in for the 18K service. The second, when it was in for the pretty unusual leak between the engine and transmission, was fixed at 35.6K. I'd checked the final drive oil level on occasion on that one, and it never budged. I just asked 'em to check it out, given the bike was almost wholly disassembled anyway.

[GTman]

Well, the leak isn't in the rear drive. I checked yesterday and the oil in the boot is a nice gold color. There's no sign of any dye being mixed in. So now I can schedule a few minutes for the dealer to witness it and then have it fixed during my 24k service.

[Beech]

Hi, that oil dye idea is great for two competing sources. I have found that spray foot powder works well for finding a source. Clean the area with some favorite cheap solvent. Let the area dry and spray with the foot fungus powder spray. It shows the smallest leaks. Beech

[Calvin (no socks)]

Don't use the medicated powders....