Gear oil leak

Hello all. I have a 99 R1100. I recently changed the oil in the transmission and final drive. It has begun leaking from somewhere. I can't pinpoint the exact origin of the leak, but the fluid is coming from the area of the transmission, is running down the trailing arm, then dripping onto the floor by the rear tire.

I thought I was careful to put the correct amount in, and have done so before without any issues, but I am wondering if this time I overfilled.

If this happened, is it likely that I permanently damaged a seal?

The drain plug and the area in front of the plug are dry, so I am pretty sure it is not coming from there.

Any insight and recommendations as to what I should do next would be greatly appreciated.

I suppose I should just start pulling plastic off, etc., and figure out where the leak is?

Thanks!

Morning Rick

The first thing that you need to do it try your best to find WHERE the leak is coming from.

It sounds like transmission but without knowing for sure you might be chasing your tail.

Any idea on how much gear oil drained out of the transmission?

How much gear oil did you put back into the transmission?

The answer to the above might tell us something.

Thanks DR.

I did add some back in, and, although I did not measure it, I estimate it was 1/8 cup (a few good squeezes of the plastic bottle).

I filled it back close to the edge of the hole, as recommended in the maintenance guides.

Thanks DR.

 

I did add some back in, and, although I did not measure it, I estimate it was 1/8 cup (a few good squeezes of the plastic bottle).

 

I filled it back close to the edge of the hole, as recommended in the maintenance guides.

Afternoon Rick

Something not adding up here-- If you properly drained the transmission then it should have taken around 27 ounces of gear oil.

Hi DR. I just meant when I added some to make up for what had leaked out, it ended up taking about 1/8 cup to get it back up to the edge of the hole.

Like DR said, step 1 is to determine the source of the leak. Spray around the leak area with Gunk, then hose off. If the leak re-appears, you should see fresh oil where it's coming from. One possibility is a bad crush washer on the transmission filler bolt.

A graduated syringe is a great tool for adding (or removing) precise amounts of oil with transmission and FD. If necessary, slip a piece of plastic tubing over the end.

Make sure its gear oil! Which should have a stronger smell then motor oil.

Hi DR. I just meant when I added some to make up for what had leaked out, it ended up taking about 1/8 cup to get it back up to the edge of the hole.

Afternoon Rick

We need to know how much you originally put in after you drained it?

Maybe I'll re-drain/refill, and carefully measure everything, then go from there.

Does that seem reasonable?

PS: It is definitely gear oil. You cannot un-smell that stuff, lol.

Maybe I'll re-drain/refill, and carefully measure everything, then go from there.

 

Does that seem reasonable?

 

PS: It is definitely gear oil. You cannot un-smell that stuff, lol.

Afternoon Rick

Just tell us ABOUT know how much you originally put in after you drained it? (your leak might be out of the trans top vent or might be something else)-- It is very difficult to see that trans vent.

All I can say positively is that I filled it to the bottom of the fill hole. Maybe that was too much?

Unless it is just not a good idea, I will just drain and refill, and keep track of the amount. Then, see if it continues to leak.

Did you fill the gear box on the side stand or center stand?

Hello all. Sorry for the delayed response, but I had to put this aside for a bit.

I FOUND THE LEAK!

IT IS LEAKING OUT OF THE BOOT BETWEEN THE SWING ARM AND THE FINAL DRIVE.

Is that possibly just the boot, or some internal seal?

Thanks for your help!

Normally (and it is quite common), the shaft seal INTO to final drive can weep a tiny amount. This can be accelerated with aggressive riding or climatic conditions (especially with a blocked breather in the FD).

A little oil can go a long way.

Undo the ties on the Swing arm to FD boot.

Slip the boot clear. Use a mirror and torch (flashlight)and see if there is any clues the the oil is migrating down the swing arm from the gearbox. This would be extremely rare.

If it just appears to be coming from the FD input seal clean up the boot and housing. Check the oil level in the gearbox and FD.

If all is ok, just refit the cleaned boot and keep an eye on it to see if it is getting bad. Normally the amount is negligible over a 6000 mile interval.

Hello all. Sorry for the delayed response, but I had to put this aside for a bit.

 

I FOUND THE LEAK!

 

IT IS LEAKING OUT OF THE BOOT BETWEEN THE SWING ARM AND THE FINAL DRIVE.

 

Is that possibly just the boot, or some internal seal?

 

Thanks for your help!

Afternoon rlusher

It's an internal oil seal, either the rear transmission seal or the final drive pinion seal.

Sometimes difficult to tell which one.

To tell much you need to swing the final drive down the look up in the swing arm with a strong bright light.

Or clean it out then put different (identifiable) gear oil in the trans & final drive then see which one leaks out.

OR, put some dye in the final drive or trans gear oil then look with a black light to see if the leaking oil has the dye in it.

Thanks DR! I will explore further!

Hey, rlusher,

I have two '99 bikes with that FD and they both weep a little. I bought all the parts to replace the seal on the first one, then read a bunch about oils. Replacing that pinion seal is a PITA it looks like. So I decided to change the oil from syn to dino and IT SURE IS BETTER THAN IT WAS. I decided I can live with a little weep. Just have to wipe the rear rim once in a while. You might try some dino oil before cracking that FD open.

Thank you Lowndes. That is a bit of a relief, because I was imagining that trying to take that apart would not be easy at all. I may give that a try once I determine for sure that is where the oil is coming from.

Any tricks you have discovered for getting the 99 to run right? It has that wretched surge everyone talks about.

I have tried everything under the sun trying to get that thing to run smooth (valve adj, TB sync, plugs, wires, coil, fuel pump, sensors, ....) and nothing has worked. Even a mechanic looked at it and said he didn't know what to do.

Thanks again!

rlusher,

Just my personal experience and observation on my two bikes here. There are people here that have years of experience with multiple bikes and provide excellent help and advice.

If the pinion seal in the front of the FD is weeping, it will show first coming from the joint between the boot and FD, closest to the pinion seal. For a pinion leak to show at the front joint between the boot and the swing arm/shaft housing, the leak would have to fill the flex grooves in the boot first. That would take a lot longer depending on how bad the leak is.

The joints between the boot and the FD and swing arm not particularly tight, but I put the zip tie lock at the very bottom as this is the weakest point in that seal and most likely to leak. Some people want to put the lock at 3 or 9 o'clock to help keep the FD and wheel clean. I want to know what's going on.

As for the surging problem you have, I have not experienced surging in either bike. I have added an AF-Xied by Night Rider to both bikes to clean up the super lean air/fuel traits, i.e. very cold natured, low-speed stalling, balky low-speed handling and throttle response, hotter running, etc, which it does VERY nicely. I understand that it does help with the surging issue, too. You might want to do some research on it.

I did a Google on it and this popped up first: AF-Xied and Surging I'd wholeheartedly agree that it does "transform" the bike.

Under the seat in the fuse box there is a square plug, called the cat code plug or CCP. Try riding with the CCP removed. That trick always resolves surging issues for me.

I think I have one leak that is manifesting as a couple leaks. One seems to be dripping directly onto the catalytic converter (and yes the horrible smell) and the other is from the boot between the paralever and the FD. When I pulled the boot back, there was probably about 20-50 CC's of gear oil along with way too many metal filings to be cleaned ( see here). I haven't pulled my boot back after the aforementioned cleaning, but there was no leak from the boot/FD end for the better part of two weeks. I have had leaking (actual drips to the ground) from the catalytic converter area.

I'm hoping to be able to ride through the rest of the season before having to address this, but we shall see. All plugs are sealed as I inspect them so I suppose this means the whole paralever assembly has to be removed? Can this seal be replaced w/o removing the gearbox?

How critical is this leak if I keep the fluid levels in check?

Thanks,

Tim

Tim -

Please check your PM's at top of your screen under "My Stuff".

I think I have one leak that is manifesting as a couple leaks. One seems to be dripping directly onto the catalytic converter (and yes the horrible smell) and the other is from the boot between the paralever and the FD. When I pulled the boot back, there was probably about 20-50 CC's of gear oil along with way too many metal filings to be cleaned ( see here). I haven't pulled my boot back after the aforementioned cleaning, but there was no leak from the boot/FD end for the better part of two weeks. I have had leaking (actual drips to the ground) from the catalytic converter area.

 

I'm hoping to be able to ride through the rest of the season before having to address this, but we shall see. All plugs are sealed as I inspect them so I suppose this means the whole paralever assembly has to be removed? Can this seal be replaced w/o removing the gearbox?

 

How critical is this leak if I keep the fluid levels in check?

 

Morning Tim

Leak wise probably not a big deal but FIRE WISE it could be a big deal if oil drips onto a hot catalytic converter & ignites.

Can you tell if it is engine oil or gear oil dripping onto the cat?

Have you drained the air box of excess oil?-- There is an air box drain valve on bottom left rear of air box. You might drain that to see what comes out. If a lot of oil comes out that could be some or all of the oil drip on the cat.

If your leak is a rear trans seal then that can be replaced by removing the swing arm & drive shaft.

The metal shavings are something to identify though at that usually points to problems other than JUST an oil leak.

Thank you Lowndes! Some excellent insight here.

Thank you Jim. I have removed the CCP before and let it run for a few minutes, and it did not seem to run any different. Could it be that if I actually ride it for a while, that it I will notice a difference? Thanks again.

You gotta ride it.