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Well, it looks like I have either a pinion seal or transmission seal going south. I washed my LT for the first time this year and found a pretty heavy oil/dirt film on the FD under the boot. The leak appears to be slow as it wasn't really wet and it hasn't yet dripped on my garage floor. However, I don't recall seeing it when I washed the bike before storage last fall nad I have ridden less than 400 miles thus far this year.

I haven't yet tried to ascertain which end is leaking into the drive shaft housing, but will do that once the bike is inside on the level so I can check the FD oil level and tranny oil level. I am not sure it has leaked enough yet to affect the level greatly, but hopefully I can get some indication as to which end is leaking.

Haven't even made 4 years or 25,000 miles yet. Pretty sad for a $22,000 motorcycle.

Other than oil level checks, any other suggestions as to how to determine for sure the source of the oil? Particularly, if the oil levels aren't low enough to be sure from that? I guess keep riding until it gets low enough! :)
 

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First check your drain plug magnet for signs of failure. All you should see is gray fuzzies. Any shiny large particles or chunks and you're on the last leg. Failure is imminent and at that point the bike should not be ridden. If you don't find anything unusual try changing to non-synthetic FD oil and the seepage may stop. Also it may be a temporary issue from setting over the winter. Take a few short trips and keep an eye on it before you get too excited. If it does need rebuilt consider sending it to Curtis (Charlie VT) and it will be fixed properly. I can't say the same for many of the dealerships.
 

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2005 K1200LT
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Oil in the boot is not a show stopper nor is it an indication of rear drive failure. You won't notice a drop in oil level but you do need to figure out where it is coming from. Best way to do that is use a different color oil (you wanted to check for debri anyway) in the rear drive than what is in the tranny. Then clean the boot area really well (inside too) and ride for a few hundered miles and see what color it is. Like I said no need to panic at this point.
 

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jzeiler said:
Oil in the boot is not a show stopper nor is it an indication of rear drive failure. You won't notice a drop in oil level but you do need to figure out where it is coming from. Best way to do that is use a different color oil (you wanted to check for debri anyway) in the rear drive than what is in the tranny. Then clean the boot area really well (inside too) and ride for a few hundered miles and see what color it is. Like I said no need to panic at this point.
Like John said but I would check the INSIDE of the boot first to see if there is any oil inside. It could be as simple as the brake overflow tube spilling onto to the outer boot. (wishful thinking)
 

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jzeiler said:
Oil in the boot is not a show stopper nor is it an indication of rear drive failure. You won't notice a drop in oil level but you do need to figure out where it is coming from. Best way to do that is use a different color oil (you wanted to check for debri anyway) in the rear drive than what is in the tranny. Then clean the boot area really well (inside too) and ride for a few hundered miles and see what color it is. Like I said no need to panic at this point.
Yes Yes Yes on what John said. I was thinking the same thing I just didn't know how to say it.
 

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Good advice so far.

Pull the rubber boot back and see how much lube is captured there.
Then remove the filler plug of the FD and look at the lube level. Don't move the bike or rotate the rear wheel or lube will be carried up on the crown gear and result in an apparent lower level.
Since you probably don't know what the level was at the time of the last FD lube change, this will only give you a base line and perhaps a suggestion that is it the FD if there is lots of lube in the rubber boot, and the level in the FD is noticeably low.

Then drain the FD lube and fill with a different color lube. It is worth looking at the FD drain plug magnet, but as noted by John in his post above, a leak at the input pinion seal is not associated with the metal generating crownwheel bearing failure.

I do have a slight suspicion that there may be an association with input pinion seal leaks and another form of FD problem, but it is only a suspicion. Since I started looking for the "wandering needle bearing race" described in this post: http://www.bmwlt.com/forums/showthread.php?t=61159&highlight=pinion+bearing
I have seen more of them during final drive rebuilds. If the race is slipping off its seat, it isn't obvious or even easy to see unless you know what you are looking for.

I have replaced few FD input pinion seals, but have done many fewer of these than I have done of crownwheel bearing replacements. I recently accepted a FD to rebuild which had a leaking input pinion seal. A concomitant finding was that the needle bearing race had started to "wander" or "creep" off its seat. I don't understand what is causing the pinion needle bearing races to move the way they are, but I now wonder if there might be a relationship to leaking input seals; just my inquiring mind, no good data, or causal relationship to point to. Just two problems occurring in the same assembly at the same time.

If there is a relationship between pinion input seal failure and the slipping (wandering) pinion needle bearing race, that relationship would easily escape detection. Reason being, the input seal can be replaced without opening the drive or removing the input pinion assembly. To do so entails significantly more, seemingly unnecessary work.

I'm probably just pissing in the wind about a possible relationship between input pinion seal leaks and input pinion needle bearing race creep. But, if the input pinion seal needs replacing, in my opinion it is worth taking the cover off the drive and looking at the input pinion needle bearing race to check its position on the pinion shaft.

The more likely explanation of a leak at the pinion input seal is that it isn't the seal itself but rather the threads of the locking ring that holds the input pinion assembly in place. During assembly the input pinion seal is pressed into the locking ring, and then the locking ring is threaded and torqued into position in the FD housing. The threads of the locking ring must be carefully coated with Hylomar or comparable sealant, or FD lube is going to leak past the threads. It would be a natural assumption that a leak at the FD input pinion is a failure of the shaft seal, but in the few I have looked at, I've been more suspicious of an incomplete sealing of the locking ring threads.

addendum: oh, you might also just top off the tranny lube with what ever color lube is already in there, just in case it is the tranny output seal that is leaking. You probably could go a long time before the lube level becomes too low in the tranny but why take chances.
 

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Voyager said:
Well, it looks like I have either a pinion seal or transmission seal going south. I washed my LT for the first time this year and found a pretty heavy oil/dirt film on the FD under the boot. The leak appears to be slow as it wasn't really wet and it hasn't yet dripped on my garage floor. However, I don't recall seeing it when I washed the bike before storage last fall nad I have ridden less than 400 miles thus far this year.
I would look very hard at the transmission output shaft seal. It can drain down the center of the swing arm. The oil level of the transmission can be monitored fairly easily and you should be able to see a faint oil trail if you have a sizable puddle in the boot.
 

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Discussion Starter #8
CharlieVT said:
Good advice so far.

{Much good stuff deleted}

addendum: oh, you might also just top off the tranny lube with what ever color lube is already in there, just in case it is the tranny output seal that is leaking. You probably could go a long time before the lube level becomes too low in the tranny but why take chances.
Yes, I appreciate all of the good advice.

I am going to check the level this afternoon, but want to get some new lube before I check the drain plug. I can't see putting the old oil back in.

I am pretty sure that the dealer put synthetic lube in both tranny and FD at the 12K service. It would be great if that was related to the leak, but I have ued synthetic oils for nearly 30 years and really haven't noticed them causing any more leaks, at least not in a vehicle that didn't already have a leaking problem.

I have ordered some Castrol Hypoy C since I can't find it locally. I am not sure the brand of lube makes that much difference, but Tom Cutter is a strong proponent of the Castrol stuff and I respect his experience and opinion. I think I have some Valvoline in my shop and I suppose it wouldn't hurt to use that for a few days until the Castrol arrives. That would let me check the drain plug sooner.

My boot has a metal clamp on the front side and a plastic tie wrap on the back. What is the recommened way to loosen the boot to check the amount of oil inside the swing arm? Loosen the metal clamp and slide that back? Cut the tie wrap and then replace it? The tie wrap end is a little lower so it likely would let a little more oil out, but the metal clamp is the easier route.

I checked for wheel play and it still feels very tight and the tire rotates smoothly with just the normal brake drag and noise. I tend to think it isn't the large bearing going bad, but just a seal in the FD or tranny, but your theory about the pinion bearing issue being related to pinion seal leaks is certainly an interesting one.

It does seem odd to me that the LT seems to have such short-lived seals. My cars now routinely go 100,000 miles with no seal issues, yet it seems the LT eats seals like Wheaties. Seems odd unless something is out of whack mechanically.

I had the front axle on my Chevy truck rebuilt two years ago. It had 110K miles of snow plowing on it and the bearings where the left axle entered the differential had at least 1/16" of play in them! You could shake the axle up and down where it entered the housing yet even with this much slop the seals still didn't leak a drop! I was impressed.
 

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Discussion Starter #9
Some interesting, but good news.

I checked the wheel again for any play and it is tight as a drum head.

I removed the metal boot clamp and slide back the large end of the boot. I had a pan to catch the oil that I was sure was in there, but got ... almost nothing. About 4 drops of water and just enough oil to make things slippery on the boot and housing, but not enough oil to even call it a drop. So, I wiped things as clean as I could and put the boot and clamp back on.

I checked the FD oil level to have a baseline and the level is about where I would expect. It was right at the bottom of the threads on the filler hole. It is also red in color so I believe that suggests it is the BMW synthetic as I recall reading here some time ago that the BMW syn was red.

So, for now I will keep "riding it like I stole it" and monitor it. It is coming up on the 24K soon anyway so that will give me a good chance to look things over well with the tupperware off. And I plan to replace the tranny and FD oil with Hypoy C so that will rule out the synthetic oil as a potential leak enhancer, though I really don't think synthetic oil is an issue.

Thanks to all that responded and I will post back should something further develop.
 

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Just a note for the future. When the wheel gets wobby (big bearing failure) the oil won't be at the boot but at the main seal on the crown gear. Only two things put oil in the boot and that is the tranny output seal (they had a bad production batch on some 05 and early 06) or the pinion seal. Zippy GG had a pinion seal go bad on his 05 but the drive was fine and still going strong several K after the seal was replaced. My tranny seal leaked at 18K and the replacement is still bone dry at 63K.
 

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Discussion Starter #11
jzeiler said:
Just a note for the future. When the wheel gets wobby (big bearing failure) the oil won't be at the boot but at the main seal on the crown gear. Only two things put oil in the boot and that is the tranny output seal (they had a bad production batch on some 05 and early 06) or the pinion seal. Zippy GG had a pinion seal go bad on his 05 but the drive was fine and still going strong several K after the seal was replaced. My tranny seal leaked at 18K and the replacement is still bone dry at 63K.
I wasn't too concerned about my FD having the bearing issue, but a leaking pinion isn't a picnic either.

I was in contact with Tom Cutter and he said that often leaks such as mine are due to the FD being overfilled. At his recommendation, I plan to drain the FD and install the measured amount of oil rather than filling to the threads of the fill hole as is the case now. And I am taking out the synthetic and using the Castrol Hypoy C.

Then back to riding and checking on it periodically. I have never noticed any play in the rear wheel, but I will keep an eye on that also.
 

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Discussion Starter #12
Since I cleaned it up a few days ago, it has seeped just a little down the housing as shown in the picture. This after maybe 40 miles of riding and a week or so of time.

I changed the FD oil today and am encouraged by what I saw. Attached are some pictures, but basically other than a drain plug that was way over-tightened, things looked pretty good. The oil that came out was very clean after probably 10,000 miles (the bike has 22,700 and the dealership did the 12K maintenance) and the drain plug had only a small amount of sludge on it, no pieces of metal of any discernible size.

I cleaned up the drain plug and replaced it and torqued it to the BMW spec of 23 Nm and the crush washer did not dish out and distort as had the one that was on the plug when I removed it. Looks like it was WAY over torqued. I hope the threads in the FD aren't damaged as the plug was somewhat hard to screw out and I had to use the wrench to remove the plug until only a couple of threads remained. It did screw back in easily with just my fingers after I cleaned it up so hopefully the threads are OK in the housing.

I put Castrol Hypoy C back in per Tom Cutter's recommendations and also refilled with 220 cc of oil rather than filling to the bottom of the fill hole threads. I could easily see the level and it was down just a little below the bottom of the hole. Tom's recommendation is 10 cc less than BMWs and he said he has found this to be less troublesome from a seal seepage perspective.

So, no signs of bearing failure or other metal related distress and the oil that came out looked almost new. Tom is fairly confident that the slightly lower oil level and the use of dino oil will stem the leak, assuming the leak is from the pinion seal. If it is the transmission, well that will be another story. For now, ride and monitor!
 

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Well, things are going downhill since I last posted. I have ridden a little more than 2,000 miles since changing the final drive oil from the BMW red synthetic to Castrol Hypoy C hoping to stop a slow weep I had at the boot.

The leak at the boot keeps getting worse and I began to wonder if it was the FD leaking or maybe the transmission. Since I have 25,000 on it now and it was due for an engine and transmission oil change as well, I did both today. Well, what I found when I got under the bike was not good. It is leaking oil from pretty much every seam. It is leaking at the boot, at the transmission to bell housing joint and at the bell housing to engine housing joint. I am not sure if the LT has a bell housing per se, but there appears to be two joints between the engine block and the transmission so I am calling it a bell housing for lack of better knowledge.

The clutch isn't slipping yet, but I suspect it is just a matter of time and probably not much time at the rate it is getting worse.

The interesting part is that the transmission oil did not seem to be low at all. When I removed the fill plug before I drained the oil, the level was right at the bottom of the hole and actually slowly started to seem out of the hole. And the really strange part is that the oil that is leaking does not look red in color at all even though both the FD and transmission had red oil in them from the 12K dealer service. But the leaking oil does have the distinctive gear oil smell. Maybe the leak is slow enough that the dirt and such make it look black when on the outside parts.

It is sad that a bike can't make 25,000 miles without leaking oil at every seam. I think Harley's even do better than this nowadays! It looks like some very expensive and time consuming repairs are in my future.
 

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I had a look like your middle picture on my bike at about 40K. Cleaned it up with spray degreaser and it never returned (now at 64K). Not sure where the stuff came from.
 

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jzeiler said:
I had a look like your middle picture on my bike at about 40K. Cleaned it up with spray degreaser and it never returned (now at 64K). Not sure where the stuff came from.
I haven't cleaned mine up fully yet, but will when I next wash it as I spilled a litle more on the center stand while draining the tranny. What a PITA that is!

I am hoping beyond hope that removing the synthetic gear lube will allow the leaks to heal, but that is probably not a rational hope. :)

In any event, given the effort required to tear it down as compared to the fairly small cost of a clutch disk, I am going to just keep riding it until the clutch starts to slip and then decide if I tackle the job myself or take it to Tom Cutter. Given that I don't have a lift and don't have a winch to hoist it from the ceiling, I will probably try to get Tom or someone of his caliber to tear it down, check the FD thoroughly for preload, etc., replace all required seals, and basically go over it thoroughly.

I am hoping it makes it to winter before I have to do this, but that is probably another irrational hope!
 

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Don't give up hope. My clutch started slipping in June and I rode it all the way to September before I decided to tear into it.
 

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jzeiler said:
Don't give up hope. My clutch started slipping in June and I rode it all the way to September before I decided to tear into it.
Did you do a write-up on your experience replacing the clutch? I did a quick search on your name and clutch and did not find anything.
 

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I have been going after the same problem as you and here is what i have done, put a small drain hole in the low part of the bell housing, lower the oil level in the trans a quarter inch below the fill hole and mine has slowed to a drop or two out of the output seal\boot and no more oil comming from the bell housing drain hole. The clutch slip has stopped.
 

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Voyager said:
Did you do a write-up on your experience replacing the clutch? I did a quick search on your name and clutch and did not find anything.
Here's a link to the thread that can help you through the process. It's intimidating at first, but once you go, it's not too bad!
 

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Voyager said:
Did you do a write-up on your experience replacing the clutch? I did a quick search on your name and clutch and did not find anything.
I did not do any filming but I did shoot a few pics. Shoswell covered it pretty good in his posts. You can start with the weep hole videos I put out as that will get you up to the point you need to start prepping the engine/trans combo for a tilt down to clear the frame. If I go in again on mine or another I will document it.
 
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