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"KRS/GT" Technical Q&A K1200RS/GT Technical Questions/Answers

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View Poll Results: Have you had the dreaded rear main seal leak?
Yes, and I use dino oil. 37 9.41%
Yes, and I use synthetic oil. 44 11.20%
Yes, and I have used both dino & synthetic oil. 28 7.12%
No, and I use dino oil. 63 16.03%
No, and I use synthetic oil. 154 39.19%
No, and I have used both dino & synthetic oil. 35 8.91%
Yes, and I use dino/syn blended oil. 1 0.25%
No, and I use dino/syn blended oil. 14 3.56%
This thread is a waste of bandwidth. 17 4.33%
Voters: 393. You may not vote until 'registered'. Please go here: http://www.i-bmw.com/register.php

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  #1  
Old 08-07-2007, 11:41 AM
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Question Engine seal leaks and synthetic oil

Are these related as with the transmission?
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Old 08-07-2007, 11:54 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by BMW
Are these related as with the transmission?
Some will say yes, and some will say no. I have 14,000 miles with synthetic all around and no leaks yet (knock on wood).
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Old 08-07-2007, 12:37 PM
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Re: Engine seal leaks and synthetic oil

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Old 08-07-2007, 12:39 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by JamesTexas
Elaborate please, James. You think they're not related?
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Old 08-07-2007, 12:42 PM
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Thumbs up Re: Engine seal leaks and synthetic oil

My 2001 rs started leaking before I used synthetic and on the 2004 I have 18,000 miles with synthetic and no problems so far.
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Old 08-07-2007, 12:47 PM
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Re: Engine seal leaks and synthetic oil

The most you can hope to find here are anecdotes.

A causal link would have to involve a detailed study.

Unless anyone knows of one, this thread is a waste of bandwidth.
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  #7  
Old 08-07-2007, 01:09 PM
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Re: Engine seal leaks and synthetic oil

Let's make it anecdotal then.
Please vote, then reply with your anecdotes.
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Old 08-07-2007, 01:23 PM
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Exclamation Re: Engine seal leaks and synthetic oil

Another ...pole
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Old 08-07-2007, 01:46 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by JamesTexas
Another ...pole
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Old 08-07-2007, 02:54 PM
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Re: Engine seal leaks and synthetic oil

None yet, knocking on wood
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  #11  
Old 08-07-2007, 03:19 PM
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Re: Engine seal leaks and synthetic oil

Frankly, after a close inspection of the seals BMW has used on the RS, I am not surprised that there are numerous leaks. I replaced my short block 27K miles ago in my '02, and as Rick has voiced: "knock on wood", neither my tranny seal or main seal have leaked. The seals are like a hard silicone/lexan/plastic like material that because of it's reversed cup installation, requires friction and heat to make it seal properly. Why they couldn't use standard engine seals that use a spring to pressure contact is beyond me. Bars makes a product to repair leaks.
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  #12  
Old 08-07-2007, 04:02 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by tward
The seals are like a hard silicone/lexan/plastic like material
Silicone and lexan are just about as different as any two polymers can be! Silicone is soft and supple, and lexan is hard and inflexible. I have no idea what a "silicone/lexan/plastic like material" could possibly be like, other than to say it cannot exist!

In fact, all BMW seals are made of butyl rubber, with the later rear main seals having a thin wear resistant coating of what appears to be a fluorocarbon material on their lips.

Generally speaking, this survey has a problem. Many of the supposed rear main seal problems have nothing much to do with the main seal at all!

On brick motors, the most common source of leakage is the O-ring that fits between the inside of the clutch basket hub and the engine's output shaft. This butyl O-ring tends to get overheated (possibly due to heat from the clutch) and gets as hard as a rock.

Some years ago I had what I thought was a rear main seal leak, but upon disassembly, I found the actual rear main seal was in fine shape (even after 130,000 km at that time). The above-mentioned O-ring was so hard, it snapped in two when I tried to remove it. All I did was replace the O-ring and left the main seal alone. Five years and 50,000 km later, the bike does not leak a drop.
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  #13  
Old 08-07-2007, 05:39 PM
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Re: Engine seal leaks and synthetic oil

I use Castrol Syntec (synthetic blend so both bases are covered), how about a choice for blends?
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  #14  
Old 08-07-2007, 08:54 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by Protechmarine
...how about a choice for blends?
Done.
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  #15  
Old 08-08-2007, 11:28 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by JamesTexas
My 2001 rs started leaking before I used synthetic and on the 2004 I have 18,000 miles with synthetic and no problems so far.
So, at least in one case, dino did not prevent the leak.
Thanks for the input.
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  #16  
Old 08-08-2007, 08:35 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Generally speaking, this survey has a problem.

Of course.

Suppose 75% of the bikes having leaks used synthetic.

Tells you nothing unless you know what percentage of the fleet is using synthetic.

IOW, if 90% of the bikes are running synthetic, it may actually be helping.

Its like at bike week when the majority of bikes broken down by the side of the road are Harleys. Of course they are - says nothing about their reliability if the majority of bikes are Harleys - of course they'd be over-represented.
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Old 08-08-2007, 09:42 PM
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Re: Engine seal leaks and synthetic oil

Seemed like a simple poll I was interested in till you all hammed it up. Could we get the information first then decide if we can make a valid assesment??
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Old 08-09-2007, 08:52 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Could we get the information first then decide if we can make a valid assesment??

Sure.

Data collection is an important first step.

But until we can normalize for such variables as the owner's age, riding habits, drug use, religion and astrological sign, it will be hard to draw meaningful conclusions.
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Old 08-11-2007, 10:48 AM
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Re: Engine seal leaks and synthetic oil

Can I change my vote? I've voted 'No, and I have used both dino & synthetic oil.?' but it's leaking now and the clutch has gone and the plastic is off and there is oil everywhere and I'm sad and and and...
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  #20  
Old 08-11-2007, 11:53 AM
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Re: Engine seal leaks and synthetic oil

Quote:
I've voted 'No, and I have used both dino & synthetic oil.?' but it's leaking now...

AHA!

A deadly combination revealed!
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  #21  
Old 08-11-2007, 12:28 PM
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Re: Engine seal leaks and synthetic oil

Fellow rear main seal enthusiasts:

I had to replace the main seal (and the o-ring) on OXCART, my '98 K1200RS, last September. I posted nearly every detail. Found much useful info on this site. Now my machine has a new clutch, the new seal (don't know when BMW switched to the new style, but I have it now), o-ring, bolts, etc.

The job was beyond my comfort level. It was somewhat more complex than, say, adjusting the valves on my GS, but mostly because it involved a lot of unfamiliar territory and there were so many parts that had to come off to get to the clutch area. I would just as soon never have to do it again, but that said, if I ever have to, it will go easier.

The bike and I are both better for the experience.

Took her briefly over the dollar mark crossing the Snoqualmie Valley yesterday. Contemplating a set of Wilbers Shocks for something to do this fall.

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  #22  
Old 08-12-2007, 04:02 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by Paughco
Fellow rear main seal enthusiasts:

I had to replace the main seal (and the o-ring) on OXCART, my '98 K1200RS, last September. I posted nearly every detail. Found much useful info on this site. Now my machine has a new clutch, the new seal (don't know when BMW switched to the new style, but I have it now), o-ring, bolts, etc.

The job was beyond my comfort level. It was somewhat more complex than, say, adjusting the valves on my GS, but mostly because it involved a lot of unfamiliar territory and there were so many parts that had to come off to get to the clutch area. I would just as soon never have to do it again, but that said, if I ever have to, it will go easier.

The bike and I are both better for the experience.

Took her briefly over the dollar mark crossing the Snoqualmie Valley yesterday. Contemplating a set of Wilbers Shocks for something to do this fall.

Seeya
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Yes Paughco, I've just been there, wheeled the motor out of the frame and rebuilt the rear drive as well. Not what you would call a 'routine service operation' - but seems to be a routine failure route!

I'll accept doing this sort of thing on a blown motor after 100K miles, but not for a few cheap seals and 'O' rings at 36k.

Perhaps it's not the type of oil that should come with a health warning but the bike!
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  #23  
Old 08-13-2007, 10:20 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by FastEddieb
AHA!

A deadly combination revealed!

Best we can hope for is a sample of respondents. But Might be telling. Way back when they always said once you start with do not switch. But my gut feeling is the synthetic is harder to hold in and will show some sepage where dino will not. Perfect world and perfect seals no problem with either.

Back to the show.....
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Old 08-13-2007, 10:52 AM
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Re: Engine seal leaks and synthetic oil

I think the survey will pop out some numbers, but the data is insufficient to reach credible conclusions.

BMW have messed around with different seal types over the years. Early seal types would have been designed and tested with dyno oils, the wear in of these seals has been done with dyno oils. Later bikes and repairs will be using BMW's Teflon seals. I'm not saying these must be better ('cos I just stuck back a pile of seals that are of the 'traditional' lip and spring construction').

I'm just making a comment that without knowing the bike year, mileage and what type seals it has, the survey results won't prove much, except that oil seals fail on BMW motorcycles which I think we already know.
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Old 08-13-2007, 11:47 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by voxmagna
I think the survey will pop out some numbers, but the data is insufficient to reach credible conclusions.
??
BMW have messed around with different seal types over the years. Early seal types would have been designed and tested with dyno oils, the wear in of these seals has been done with dyno oils. Later bikes and repairs will be using BMW's Teflon seals. I'm not saying these must be better ('cos I just stuck back a pile of seals that are of the 'traditional' lip and spring construction').

I'm just making a comment that without knowing the bike year, mileage and what type seals it has, the survey results won't prove much, except that oil seals fail on BMW motorcycles which I think we already know.

Survey needs to be build date specific?
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  #26  
Old 08-29-2007, 08:41 AM
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Red face Thanks for all of the input and feedback..

The original question was meant to be simplistic and not to detect subtle differences.

For example, a major oil factor would have been shown if all leaks were with synthetic and none occurred with dino.

The riding styles and mileage vary enough among us that most conditions have been sampled.

It appears that oil type alone (dino versus sythetic) is not the major factor in producing seal leaks.
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Old 08-29-2007, 10:18 AM
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Re: Engine seal leaks and synthetic oil

You left out Royal Purple
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  #28  
Old 09-10-2007, 10:48 PM
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Re: Engine seal leaks and synthetic oil

I have a2004GT and the dealer put in seals in the input and output shaft but the main seal. I would thing that if you have bike apart you would replace out the seals at that time.
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Old 09-25-2007, 11:01 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by majicdoor
I have a2004GT and the dealer put in seals in the input and output shaft but the main seal. I would thing that if you have bike apart you would replace out the seals at that time.

That's what I did, even managing to get Viton for most of the critical locations. But then some say don't worry just do each seal as it fails. They must have deep pockets or a lot of spare wrenching time. When you eventually get that frame off and the motor out you don't want to go back there too soon.

At 36K all my seals were very hard which I put down to the excessively high (oil) running temperatures over the bikes relatively short road life. Riders use their bike differently. I suspect a high mileage spent mainly on touring is far better than urban riding particularly in hot climes. If I was looking at a new bike now, I'd pay more attention to their cooling system design. I'd check out the coolant capacity for clues to radiator size, look at their core sizes, run it on the stand until fans came on then time how long (if at all) it took for fans to cut out.

If I was a betting man and could put an hour meter on a bikes fans from new, I'd bet bikes with the longest 'fans on' average per kilometer ridden will give the worst seal problems.
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Old 10-02-2007, 05:12 PM
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  #31  
Old 10-02-2007, 06:22 PM
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Re: Engine seal leaks and synthetic oil

Just had the main seal and 'o' ring replaced..main seal looked ok..but 'o' ring was so brittle that it fell apart..which was the cause of the leak. FYI..I consistently used BMW (non-synthetic) oil in the engine thrue out the my ownership of this '98 K12RS.
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Old 10-03-2007, 03:40 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by aa3jy
Just had the main seal and 'o' ring replaced..main seal looked ok..but 'o' ring was so brittle that it fell apart..which was the cause of the leak. FYI..I consistently used BMW (non-synthetic) oil in the engine thrue out the my ownership of this '98 K12RS.

I agree with the condition you found your seals, mine were the same on my '97 BUT not leaking at 36K miles. The clutch O ring is a slightly different case, because clutches can get very hot if worked hard and this heat combined with high oil temperatures will harden the O ring more quickly. Some people put synth in their transmissions and rear drives (??) and you don't hear so much about those seals failing, yet they are doing similar revolutions. The clutch O ring seals in an unusual way. Most O rings suffer only about 10% compression to seal so the honecomb rubber core retains elasticity. The clutch O ring is compressed to hell by the clutch nut so much that it changes shape from a round to square cross section.

However, I still think the true cause of seal failures on K-bikes (when car seals can go 100-200k) is the high and sometimes over high engine running temperatures. I don't believe it's just down to synth or non-synth oil, even though putting it in after many miles without a leak seems to cause one. The seals are shot due to excessive temperature cycling before the synth goes in!

The oil companies will claim compatibility for both Dyno and Synth, provided the oils are running in their specified temperature range. But we don't know if Buna-N seals lose their elasticity faster in a synth oil running at higher than spec temperatures, compared to the same situation for a dyno oil. Temperature and chemical activity are the main causes of changes to the properties of elastomers used in seals.

If solutions were found to lower oil temperatures by better design of the cooling system, then I suspect seal failures on these bikes would decrease.
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  #33  
Old 10-03-2007, 07:51 AM
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Cool Re: Engine seal leaks and synthetic oil

Vox, I have had ideas as how to achieve this very thing and again will mumble my on going thinking --replace the oil cooler with a larger unit ---I think if I found the manufacturer i could find a similar but larger oil cooler----but in good casuse and effect testing I should attach a oil temp meter first to see if a change in cooler size shows any temp change----got this idea after installing tranny coolers on trucks and found them to be major improvement on life cycle of the tranny ---BMW could survey owners as to climates they operate the bikes in and see if cooler/ cold climates have fewer seal issues too ---Jim
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Old 10-03-2007, 10:12 AM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by jamesgang
Vox, I have had ideas as how to achieve this very thing and again will mumble my on going thinking --replace the oil cooler with a larger unit ---I think if I found the manufacturer i could find a similar but larger oil cooler----but in good casuse and effect testing I should attach a oil temp meter first to see if a change in cooler size shows any temp change----got this idea after installing tranny coolers on trucks and found them to be major improvement on life cycle of the tranny ---BMW could survey owners as to climates they operate the bikes in and see if cooler/ cold climates have fewer seal issues too ---Jim

I've been experimenting with radiators to on the cooling side. Got a pair of fabricated copper/brass - but they're not right, I've learned a lot and now know which way I should have gone. Even so, the space up front is really restricting and trying to overcome the oem integrated stat and bypass to do something remote in a small size has so far been a big problem. I think on these bikes and especially for urban and touring you have to look at decent cooling at very slow and idle speeds. When the stat moves off the middle I've always said the cooling system is out of control and the best indicator is the enormous time it takes the fans in very hot weather to bring the temperature down. The other clue to bad things design wise is the very high operating pressure of the cooling system. I'm now saying to myself that if I revisit cooling again and try changes, I won't accept less than a 20% increase in capacity from the design objective. Anything less isn't worth the effort.

Now back to oil cooling. There's a thermostat at the base of the pump for the cooler. Quite simply, if you put any sort of thermometer (differential) across the cooler, once input = output temp the cooler is useless and would probably benefit a fan. You have to be careful to make sure the oil temp thermostat is still the final controller because cool oil is bad for engines.

I've been thinking that a much larger trapezoid shaped oil cooler/ extra rad in the front between the oil pump and the bottom of the rads might work, but needs a fan and collision with the front fender is a real big problem down there. The other place I've wondered about is between the bottom of the motor and the engine cover, but might get some stones up there. I don't think the present cooler is worth doing anything with fan wise as it has very little core area.

I think all the oem cooling on these bikes is designed around high speed, whereas for reliable long engine life I'd put cooling design objectives the other way around.

I'm afraid surveys like this aren't too scientific and as I said before, I suspect those riding with fans on a lot are either in the city or on the highway in hot climes and irrespective of the oil they use might have more seal problems.

You'll know from your car and truck work that many manufacturers incorporate larger radiator cores for vehicles operating in hot climes. I've never got to the bottom of what if anything BMW do on motorcycles, but my suspicion is they just move the radiator cap spec up to the max at around 20psi. and tell customers it's normal for fans to stay on a lot. That's a bit of a fudge, since what's normal is seeing the temperature guage stay at midway whether you ride in slow traffic or highway, or run the bike on idle. If the fans have to come on in the hottest weather, fast cooldown to normal temperature is an indicator of an adequate reserve in the cooling system design. These bikes don't do that.
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Old 10-03-2007, 01:03 PM
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Re: Engine seal leaks and synthetic oil

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Originally Posted by aa3jy
Just had the main seal and 'o' ring replaced..main seal looked ok..but 'o' ring was so brittle that it fell apart..which was the cause of the leak. FYI..I consistently used BMW (non-synthetic) oil in the engine thrue out the my ownership of this '98 K12RS.
Same thing happened with my old K100RT 5 years ago. I left the seal alone because it was in near-new shape (in spite of the bike's age.... see below).

The O-ring on the other hand had suffered from excessive exposure to heat and was (as you say) brittle and broke apart. The hardening of the O-ring on Brick motors has nothing whatsoever to do with oil, but is heat related, and appears to be caused by heat from the clutch. At the time I replaced it, I had the motor apart, and NONE of the other O-rings in the entire motor was brittle like this. Only the one around the output shaft was affected. So it obviously has nothing to do with oil.

After leaving the original rear oil seal alone and reassembling the motor (having replaced the output shaft O-ring (as well as most other O-rings), 5 years later the bike STILL does not leak a drop of oil.

Last winter I had the clutch out to lube its splines, also pulled the bell housing off to fix a baulky starter clutch. After I pulled the clutch basket off the output shaft, I checked the condition of the output shaft O-ring. It was perfectly pliable. I was going to replace it anyway, but the dealer didn't have one in immediate stock, so I just put the old one back. Still not a drop of oil leakage.
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Old 11-27-2007, 01:18 AM
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Re: Engine seal leaks and synthetic oil

Hello what a topic, I have know Scientific Cool suff, only thing i know about oil is one it lubricates and two they add additives for all kinds of reasons, like motorcycles vrs auto, antifoam agents and additives to swell up your seals so the seal better with age, stuff like that, I run my k engines 6000-8000 miles between oil changes- unless its 90-105 degress ambiant then ill change around 3000-4000 miles, if the seal goes i just replace it,myself...Im a Royal Purple Fan, to keep my temp down on the engine I use something called Ice for glycol,, it keeps my engine fans from running so long in high temps, which seem to make my engine cooler.....matthew
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Old 11-27-2007, 12:52 PM
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Re: Engine seal leaks and synthetic oil

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Hello what a topic, I have know Scientific Cool suff, only thing i know about oil is one it lubricates and two they add additives for all kinds of reasons, .......
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Old 11-28-2007, 07:52 PM
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Quote:
Originally Posted by RFW
The hardening of the O-ring on Brick motors has nothing whatsoever to do with oil, but is heat related, and appears to be caused by heat from the clutch. At the time I replaced it, I had the motor apart, and NONE of the other O-rings in the entire motor was brittle like this. Only the one around the output shaft was affected. So it obviously has nothing to do with oil.

Best explanation yet!

It appears to follow that the way the clutch is used/abused may result in more or less heat.

High rpm launches and riding the clutch would lead to premature seal deterioration and the the infamous leak.
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Old 11-28-2007, 09:06 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by BMW
Best explanation yet!

It appears to follow that the way the clutch is used/abused may result in more or less heat.

High rpm launches and riding the clutch would lead to premature seal deterioration and the the infamous leak.

I've wondered if the type of riding has something to do with seals going bad. Riding in traffic building heat vs open road, lots of air.
Maybe a poll with those options.
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Old 12-02-2007, 08:21 AM
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Re: Engine seal leaks and synthetic oil

I am using Mobil ONE 15 - 50 and change every 6K, and using Red Line Heavy Shock Proof Gear Oil in tranny and final. I had been changing the final and tranny at 12K but I am going to start changing the Final every 6K with the regular engine oil change based on the recent article in BMW ON, Bench Wrenching by Paul Glaves, Nov '07, pg 26.


This is the same synthetic oil brands and weights I used with my 2000 LT and never had problems with that one. So far all is well with the RS and have been running this for over a year.

My LT and RS had been on BMW dino oils prior to what I am running now.
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Old 01-18-2008, 07:20 AM
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Re: Engine seal leaks and synthetic oil

What viscosity synth are you using in the trans and FD? The dealer suggested that synth should be 140, while dyno should be 90. Not sure I agree. Hmmm.
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Old 01-18-2008, 08:11 AM
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Re: Engine seal leaks and synthetic oil

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Originally Posted by Chocaholic
What viscosity synth are you using in the trans and FD? The dealer suggested that synth should be 140, while dyno should be 90. Not sure I agree. Hmmm.

I use RED LINE Synthetic Heavy Shockproof Gear Oil. It is 75W90 but the marketing on the container says that it is chemically rated at 75W250. Translation is that while it is a 75W90 it behaves, according to RED LINE, as a 75W250.

I started using it on my LT after a mechanically knowlegeable buddy of mine reported his use of it on his KRS. I sold the LT one month after purchase of the RS. The only thing I do different is I change the Final when I change the engine oil. It takes one quart, $10 USD, for both the Final and the Tranny. It can be found in any town that has a race shop and in some auto parts stores.

Because I cannot always count on a BMW shop being available across the country I like using products that are easily procured and that I am familiar with when on the road. Less to carry on the bike.
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Old 01-30-2008, 01:51 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by bayoubmw
I use RED LINE Synthetic Heavy Shockproof Gear Oil. It is 75W90 but the marketing on the container says that it is chemically rated at 75W250. Translation is that while it is a 75W90 it behaves, according to RED LINE, as a 75W250.
The viscosity rating has nothing to do with the oil's "chemical rating".

What 75W250 means, is that when cold, the oil has the same viscosity that a "straight" 75 weight oil would have at that temperature, but when heated to 100C, it will have the viscosity that a "straight" 250 weight oil would have at 100C.

In short, the oil will be thin enough at cold temperatures to work properly, and will not thin out much when hot.

Note that this only applies to new oil. In a gearbox, extreme multigrage oils like 75W250 contain a relatively high proportion of polymers called "viscosity index improvers" which stop the oil from thinning out as much at high temperatures. These are long-chain polymer molecules that tend to get chewed up into shorter pieces by the gears, reducing their effectiveness. So what starts out as a 75W250 oil (in this case) gradually degrades and can end up as a much thinner oil over time.
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Old 01-30-2008, 03:55 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by Chocaholic
What viscosity synth are you using in the trans and FD? The dealer suggested that synth should be 140, while dyno should be 90. Not sure I agree. Hmmm.

Do a search....I distinctly recall BMW not recommending synthetic in the final drive.....tranny OK.
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Old 01-30-2008, 06:41 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by RFW
The viscosity rating has nothing to do with the oil's "chemical rating".

What 75W250 means, is that when cold, the oil has the same viscosity that a "straight" 75 weight oil would have at that temperature, but when heated to 100C, it will have the viscosity that a "straight" 250 weight oil would have at 100C.

In short, the oil will be thin enough at cold temperatures to work properly, and will not thin out much when hot.

Note that this only applies to new oil. In a gearbox, extreme multigrage oils like 75W250 contain a relatively high proportion of polymers called "viscosity index improvers" which stop the oil from thinning out as much at high temperatures. These are long-chain polymer molecules that tend to get chewed up into shorter pieces by the gears, reducing their effectiveness. So what starts out as a 75W250 oil (in this case) gradually degrades and can end up as a much thinner oil over time.

Obviously I used the wrong word when I said chemical makeup, but the next line where I discuss viscosity I believe is consistent with what you said regarding viscosity.
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Old 03-21-2008, 05:27 AM
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Re: Why use Synthetic oil anyway??

I don't expect my bike to manage 100-200K miles without seal and leak faults (although I wish it could) and I read of very few serious engine, oil, or bearing problems. But I do read of many seal problems which are expensive to fix.

So without quoting the marketing blurb, what advantage (measurable and realizeable) is there to using synthetic oil in an old motor design?

I run dyno, change it 4-5K miles and don't do track. It's no big deal.
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Old 03-21-2008, 09:52 AM
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Re: Why use Synthetic oil anyway??

Quote:
Originally Posted by voxmagna
I don't expect my bike to manage 100-200K miles without seal and leak faults (although I wish it could) and I read of very few serious engine, oil, or bearing problems. But I do read of many seal problems which are expensive to fix.

So without quoting the marketing blurb, what advantage (measurable and realizeable) is there to using synthetic oil in an old motor design?

I run dyno, change it 4-5K miles and don't do track. It's no big deal.

It appears the groups conclusion is that heat from the clutch is causing the problems with seals. If so then it comes down to whether you think synthetic or oils classified as sythetic are better than pure dino with additives. Many folks believe that if you are changing the oil every 3K it does not matter.

Personally I have been using synthetic in all my vehicles past and present. I like the results I am getting with the synthetics. By that I mean none of my vehicles for the last 10 years have had a problem related to wear or oil viscosity or breakdown. As I mentioned earlier I use Redline in the tranny and final. That is about as sophisticated as I get after the Mobil 1 in the engine.
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Old 03-22-2008, 07:51 PM
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Re: Engine seal leaks and synthetic oil

voxmagna: You can change your engine oil every 7000-9000 miles and save yourself time, the extra cost of syn oil and savings of one oil filter makes it a wash....matthew
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Old 03-23-2008, 06:02 AM
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Re: Engine seal leaks and synthetic oil

I change my dyno oil more frequently and filter on alternate changes because more flushing in an old design K motor with a small sump, means fewer particles and contaminants washing around oil seals.

Oil is cheap whilst seals are very expensive to fix. What you save in time on extended oil changes, is washed out by the service time, off road time and labor cost of replacing a seal. Whilst synthetic oils are more expensive (because everybody is reading the claims), dyno oils seem to be getting cheaper if you aren't worried about brand.
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Old 03-25-2008, 09:53 PM
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Re: Engine seal leaks and synthetic oil

Any feedback on what seal replacement costs at the dealership? I may need to start a new BMW IRA.
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  #51  
Old 03-27-2008, 11:15 AM
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Smile Re: Engine seal leaks and synthetic oil

Between $ 1,200 & 1,600
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Old 03-27-2008, 11:30 AM
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Re: Engine seal leaks and synthetic oil

Thanks. I'm over 30k and figured it would go at least 60k before anything like that needed replacement.
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Old 03-27-2008, 12:25 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by voxmagna
I change my dyno oil more frequently and filter on alternate changes because more flushing in an old design K motor with a small sump, means fewer particles and contaminants washing around oil seals.
The old K bike sump is 4 liters ....not really a "small sump". I really don't think there is anything to worry about regarding particles washing around the sump because anything that is big enough to cause a problem with oil seals, will be taken out by the oil filter. If there are enough abrasive particles in the oil to cause seal wear, the really sensitive areas like bearings and cam surfaces would be suffering much more.
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Old 03-28-2008, 02:26 PM
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Re: Engine seal leaks and synthetic oil

I've seen filters in cars fitted with a Neodymium magnet ring and cut open after a 10K service life.

The grey deposit lining the inside of the can was to fine to be caught by the filter element and I could have used it as bath scouring cream. I'd expect seals to be more vulnerable than bearings.
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Old 04-02-2008, 10:48 AM
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Re: Engine seal leaks and synthetic oil

The lastest edition of Cycle World has a small article about such filters being available for motorcycles. This version has the magnet and is also packed with steel wool. The flow rate is touted as being much higher than with standard filters. Supposedly you can clean these filters and reuse them indefinitely.

Quote:
Originally Posted by voxmagna
I've seen filters in cars fitted with a Neodymium magnet ring and cut open after a 10K service life.

The grey deposit lining the inside of the can was to fine to be caught by the filter element and I could have used it as bath scouring cream. I'd expect seals to be more vulnerable than bearings.
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Old 05-04-2008, 09:03 PM
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Re: Engine seal leaks and synthetic oil

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Originally Posted by FastEddieb
Sure.

Data collection is an important first step.

But until we can normalize for such variables as the owner's age, riding habits, drug use, religion and astrological sign, it will be hard to draw meaningful conclusions.
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Old 05-04-2008, 11:46 PM
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Re: Engine seal leaks and synthetic oil

Quote:
Originally Posted by BMW
The flow rate is touted as being much higher than with standard filters.
Absolute nonsense. The rate of flow is governed by the oil pump alone unless the filter is so plugged that the relief valve opens.

The oil pump is a positive displacement pump. Come hell or highwater, it pumps a specific volume of oil for each revolution. You cannot reduce its "flow". All that happens is that when the filter starts to get plugged, the pump pressure rises to whatever it takes to get that oil through the filter. Eventually, the pressure rises sufficiently to open the relief valve. But through all of this, the "flow" of oil remains the same.
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Old 05-07-2008, 05:47 PM
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Re: Engine seal leaks and synthetic oil

When I opened up an oem fuel filter I learned that there's more going on inside filters than you might think. If they are using paper, or glass fibre, the objective is to trap particles whilst ensuring there is minimal pressure drop. This fuel filter had yards of convoluted paper inside. There's a guy on the web who's cut open lots of filters and compared different oem and aftermarket brands. The more filter area you can get inside with the right mesh size, the longer will be its service life whilst catching the smallest particle size it was designed for.

Now it seems to me that filters are all sealed up and it would be easy to say this or that filter may be superior. For the new product, there are massive profits to be had from people switching filter brands (same as with oils). But apart from advertising claims I would need more convincing about performance. I mentioned what happens with neodymium magnets in the context they were used around the can of an oem filter. Because our filters are immersed, there's no room around the can. Fitting something inside the can would make me question the effectiveness of a filter element with reduced area, since not all particles are magnetic steel- some being really hard stainless.

Going back many years, I do remember engines using washable mesh filters. But their top speeds were only in the 60's. and it was common to get re-bores and cranks reground.
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Old 05-14-2008, 03:09 PM
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Re: Engine seal leaks and engine braking?

Would excessive use of engine braking result in excessive o-ring heat and early break down?
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Old 05-14-2008, 03:51 PM
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Lightbulb Re: Engine seal leaks and engine braking?

Quote:
Originally Posted by BMW
Would excessive use of engine braking result in excessive o-ring heat and early break down?

Maybe ....... heat effects a lot of things
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