2005 Rear Wheel Oil Leak

[markjenn]

Hi, I've got a 2005 FJR with 22K miles. I arrived home yesterday from a short two-day tour in near freezing temps to find quite a bit of oil on my rear wheel, final drive and swingarm - a real mess. This is not a minor leak as everything in the rear wheel area of the bike has some oil flung around including the wheel, final drive pumpkin, brakes, tire, etc.

My first thought was final drive seal failure (ala BMW's typical failure mode), but the wheel hub where the splines engage the whee is dry, the drive shaft cavity is dry, the final drive oil level is right up to the fill hole, and the aft end of the driveshaft where it engages the pumpkin has only a tiny bit of seepage and no sign that even that tiny bit of seepage is moving forward to the weep hole at the bottom of the swingarm just forward of the acorn nuts. The back of the engine is completely dry and there is no oil in the airbox. And the biggest concentration of oil is forward of the final drive pumpkin.

I do have oil all the way forward towards the bottom of the shock which is a Penske. I thought this oil had just been blown forward by turbulence, but I'm now suspecting I've got a blown seal in the shock, perhaps aggravated by riding in very cold weather. The upper part of the shock with the connections to the remote reservoir is dry, but it is pretty oily down near the bottom. But this seems like a lot of oil to be coming from the shock. Any other theories I should consider?

- Mark

 

[Geezer]

How is your crankcase oil level?

 

[radman]

Buy container of dry spray deodorant. Clean bike in rear area spotless. Spray all suspect areas with deodorant. Go for short ride. All/any leaks will be quickly evident.

 

[rickysnickers]

Looks like you might have a blown rear shock. Was the bike "bouncy" at all when you rode it? If so, then I would put money on the shock theory.

Rick

 

[Fred W]

I doubt that shock oil would be that lovely brown color. Looks like engine of gear oil to me.

 

[markjenn]

Engine oil level appears unchanged, although with the capacity of the engine, it would take a relative large amount of oil loss to show up. Didn't note any change in suspension action, but with the icy roads, I was trolling.

Thanks for help. I'm probably going to clean it up, go ride, and monitor.

- Mark

 

[C&C]

Take a sniff, a lot can be gleaned by your nose; at least you can probably eliminate engine oil by smell. I'm putting my money on a blown shock.

 

[markjenn]

Take a sniff, a lot can be gleaned by your nose; at least you can probably eliminate engine oil by smell. I'm putting my money on a blown shock.

My nose isn't that good and everything back there is mixed with road grime, but it does have a bit of an exotic smell, not like I'd expect engine oil to smell. Maybe a hint of fork oil smell. I just did another inspection forward to try and see if there is any path from the rear engine oil seal to the u-joint area or other engine leaks - dry as a bone.

I'd be 100% behind the blown shock theory except that I can't really see a well defined path from the shock to the heaviest areas of oil. But in general, the oil mess generally starts at about the point where the rear shock mount is. And I have heard that cold weather can be a problem for shock seals.

Getting it back together and a sit/bounce test on the suspension may immediately tell me something.

- Mark

 

[madmike2]

Use Radman's suggestion! It'll show a clear path to the source.

 

[LSUBOY]

Note the obvious. There are only two sources of oil on the bike:

- - -The Rear end..To check for oil leak just remove the filler hole bolt and see if the oil level is low {You seem to have lost a good amount of something so the level will be obvious}

- - -The Motor...If the oil level in the rear end is not low then it has to be coming from the motor..but it probably isn't..THAT oil looks thick like rear-end oil.

Rear end seal / see fjrtech I think?

 

[mdisher]

Yeah, when my rear end sprung a leak it looked a lot like that, black n stuff. Just not so much on the top and sides. It all came out the weep hole in the bottom.

Here: https://www.dishers.com/2007/10/07/my-fjr-thinks-its-a-harley

and here: https://www.dishers.com/2007/10/29/let-the-...nal-drive-seals

 

[markjenn]

As I said before the weep-hole is absolutely and completely bone dry on the inside and the rear drive oil level is completely full. I drained the pumpkin and got exactly 200mil out which is stated capacity.

- Mark

 

[Geezer]

I'm starting to agree with your blown shock theory. The wind could blow that oil around as it drips off the bottom of the shock mount and deposit it on your drive shaft housing. You'd probably get some on the tire as well, so look that over carefully.

 

[rickysnickers]

I doubt that shock oil would be that lovely brown color. Looks like engine of gear oil to me.

You might be surprised. My Wilbers shock blew and there was brownish/black oil all over the exhaust and the swingarm.

Rick

 

[Fred W]

I doubt that shock oil would be that lovely brown color. Looks like engine of gear oil to me.

You might be surprised. My Wilbers shock blew and there was brownish/black oil all over the exhaust and the swingarm.

Rick

Yes, you may well be right. I've never actually seen well used shock oil. My ass-umption was that it would look the same (or similar) to used fork oil. But that could be a wrong ass-umption...

 

[PapaUtah]

Sure looks like a blown shock. The oil dispersion pattern doesn't look like the pumpkin is the source. Forward and higher up...or carried up by the air current....right where the shock is. Would be my first bet.

 

[markjenn]

Well, I cleaned it up and went for a ride. No further leaks. Perplexing.

The blown shock theory became less attractive as I was cleaning things up - I just didn't see a good path from the shock to the swingarm. And it's not leaking now. I suppose it could be dry of hydraulic fluid, but damping seems normal.

I could have run over some oil I suppose, but that seems like a lot of oil not to notice going through it.

Only thing I can think of now is that the cold ride aggravated a slight weep in the drain plug sealing washer for the final drive. (I skipped a new sealing washer last time and had the tiniest bit of weepage - just enough that there was a little road grunge on the plug.) Maybe it started leaking more profusely and then found a way to blow onto the wheel where it got wrapped around and flung off further forward. And while it was enough to make a mess, it wasn't enough to drop the oil level in the final drive significantly. That's the best I can do at the moment.

- Mark

 

[dcarver]

Curious. Sometimes you just have to aggravate the issue to find the root cause. Ride on, if it never returns hooray for you. Else, you will find the problem. I've chased issues for weeks on end then just gave up, rode the bike for miles on end... and in some cases the root problem became evident and in most cases the problem never replicated.

Good Luck!

 

[2WheelTiger]

I think a jealous Harley guy tossed some of his squeezins on your scoot.

I'm all for the clean/test/flog method of experimentaton.