Crank shaft rear oil seal failure.

Motorworks oil seals

Hello Ian,
I have had problems with fork seals provided by Motorworks, as has a mate , although it was fork seals for the 1150 and 1200 bikes. I ended up fitting genuine BMW seals ( as someone has mentioned , the difference in quality was noticeable). I also measured the two sets of seals and found the BMW ones to be a tighter fit. Never had a problem since. I suspect if you buy a genuine part it will prove to be a similar story.

Thanks for all the replies guys, interesting stuff.

Firstly, I’m not entirely convinced, that the oil seal is PTFE. Having said that, there is no mention in the BMW workshop manual of lubing the seal lip prior to fitting, and BMW manuals are pretty anal when it comes to specifics. So maybe It should be fitted dry, though convention for normal oil seals is to lightly lube the lip and the shaft.

I seem to recall reading somewhere that in 2012 BMW fitted a bad batch of crank shaft oil seals. If you read the history, 7mm diameter seals were used up until 2011 when they changed to 8mm diameter, which were fitted from 2011 until end of production in 2014. But this later seal has also been superseded by the current item.

One could argue that the definition of stupidity is repeating an earlier failure, and that is what I have probably done. Fitting the same type of seal supplied by the same supplier in exactly the same manner as before. So I’m expecting a repeat failure. But the bike was reassembled before I posted this thread so have no intention of redoing unless I have definite signs of failure.

On the subject of oil leak. There is no gasket between the gearbox and the engine so any oil leaking will find it’s way out and materialise on the the engine casing, and bash plate.

I did notice when fitting the seal, that the outer edge of the seal and the engine casing was not as tight a fit as I would have liked. I could easily push the seal in, so I’m wondering if that might be the source of the oil leak. So I would consider using an adhesive/sealant next time.

As to the mechanicals. The bike runs as sweet as a nut, and I’m not suspecting any mechanical issues like worn bearings etc at this stage.

Thanks again for the replies

Ian

This is exactly the same problem I had, as I said earlier. When I fitted the motorworks one I was able to push it in with my thumbs the BM one required a tap with a rubber mallet and 27mm socket.

Have posted on other threads about some Motorworks items not being as good quality as OE. Notably swingarm gaiters and some brake caliper seals. Check with Motorworks if part they supply is after market or OE (they do supply OE parts where no alternative is available). For critical items like that it is worth getting the BMW one, and often the price is the same

BMW workshop manual says, dry, and the need for a drift to press in the seal.

Kenny Rodkiss said:

BMW workshop manual says, dry, and the need for a drift to press in the seal.

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That’s interesting.. this paragraph is not included in my copy of the manual taken from the CD. All the rest is

That's fascinating. Sometimes when doing a fiddly job, I wonder how factories can possibly build a whole bike in 6 hours or whatever.

But there we are, no less than 4 special tools recommended for fitting the seal. It must be the work of moments in the engine factory

Hello everybody. My GS has 115000 km and now i have to change the seal

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The Other PaulG said:

That's fascinating. Sometimes when doing a fiddly job, I wonder how factories can possibly build a whole bike in 6 hours or whatever.

But there we are, no less than 4 special tools recommended for fitting the seal. It must be the work of moments in the engine factory

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If i recall they get no more than 2 minutes for each assembly operation they carry out.

But they do have the luxury of dedicated jigs, the correct tooling & torque wrenches to hand

Ian J Hartley said:

I would consider it. But I would have to look at the seal to confirm that it is different from the seals that I have been supplied by Motorworks, bearing in mind that I spent nearly a whole day searching the web for seals of the exact size required, and could only find one manufacturer who makes them.

The 83mm outside diameter is the clincher. All manufacturers go from 80mm to the next size up is 85mm. They don’t do 83mm, which makes me wonder why BMW chose that diameter, when they could easily have machined the casing out to 85mm.

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Don't assume that no-one else makes a seal in that size just because you can't find any results in a search of the internet. BMW may well have the seal custom made by a manufacturer who doesn't make it in that size as standard.

I don't know how much an OE seal is but as it takes you 4 days to do the job it might be worth paying the extra money for the BMW part, if/when it next fails of course

vee5 said:

Don't assume that no-one else makes a seal in that size just because you can't find any results in a search of the internet. BMW may well have the seal custom made by a manufacturer who doesn't make it in that size as standard.

I don't know how much an OE seal is but as it takes you 4 days to do the job it might be worth paying the extra money for the BMW part, if/when it next fails of course

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My research has led me to two types of seals. The Teflon type, and the standard spring supported lip type. In fact the Haynes manual for this bike Is actually quite detailed on the fitting procedure for both types. My bike has only ever had the standard Spring lip seal fitted, even from manufacture, and that is what is in there now.

I’m monitoring it, but haven’t been able to put more than a few hundred miles on it since replacement. Fingers crossed.

Ian