Rear Oil Seal

I had a throttle cable failure - off to the shop, about a 1 3/4 hr drive.

The shop returned with estimate but also said the Rear Oil Seal needs to be replaced due to it leaking. Apparently a rather extensive repair cost/time, 12 hrs.

I can find no evidence of any oil leak where I park my bike. Is this real? What would be the evidence of a Rear Seal failure?

2008 R1200RT 32000 miles.

MOD - Move this over to Hexheads/Camheads?

ohhcrap said:

I can find no evidence of any oil leak where I park my bike. What would be the evidence of a Rear Seal failure?

2008 R1200RT 32000 miles.

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Slipping clutch is one thing.

Oil seepage evident at the junction of the rear of the engine and the front of the transmission, on the bottom, probably with some road dirt sticking...?

My 2004 R1150R leaked a tiny amount of oil at rear oil seal. I was told some of these models didn’t tolerate synthetic oils. Sure enough…I switched to Castrol GTX and no more seepage. Too bad…synthetics are superior. German engineering, yet again.

Bogdan Swider
http://bogdanswider.blogspot.com

Let us not look back in anger, not forward in fear, but around in awareness.
James Thurber

bogdan said:

My 2004 R1150R leaked a tiny amount of oil at rear oil seal. I was told some of these models didn’t tolerate synthetic oils. Sure enough…I switched to Castrol GTX and no more seepage. Too bad…synthetics are superior. German engineering, yet again.

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Off topic, however...This would be the same for any higher mileage/older machines. I don't think the issue is German engineering. My 2004 R1100S has enjoyed synthetic its entire life (currently 150,000km) and leaks nary a drop.

Oil Leak

Yes….they don’t all do it, but some leak synthetic soon after break in. When I bemoan BMW oil head engineering, I have a list: The goofy brake system, Cheap plastic tank to injection connectors that must be improved before they explode, counter-intuitive turn signals many have modified. I could go on. OK…nothing is perfect, and, all-in-all, I’m happy with the basic design. Still it’s irritating-or amusing if you’re in the mood-to take in the arrogant advertising. Especially as BMW has recently been ranked below HD and the Italians in reliability.

Bogdan Swider
http://bogdanswider.blogspot.com

Let us not look back in anger, not forward in fear, but around in awareness.
James Thurber

bogdan said:

Especially as BMW has recently been ranked below HD and the Italians in reliability.

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That's because many BMW owners are a bunch of whiners.

A buddy of mine has been riding BMWs for decades. Bitches and complains about every single one of them. Yet he refuses to try anything else. So I wonder where the problem lies - the bikes or the owners?

If they're talking about the rear main seal, then you would likely find oil leaking from the bell housing (as someone else described, where the transmission mates to the engine). As I recall, my 2011 R1200R had a weep hole in that housing that would allow oil to escape if any built up in there to avoid contaminating the clutch. The benefit was you could smell that oil to determine if it was engine or transmission oil.

If that is the case and it's engine oil, it's definitely worth a try to switch to dino oil and see if that causes the seals to swell a little and stop the leak. When you eventually have to change the clutch, make sure all those seals get replaced as well. BMW dealers will love to show you a tiny leak and tell you to replace the seal and might as well throw a new clutch in there too, making it a solid $3k job.

You can also have a leak from the transmission output seal where it connects to the drive shaft (I've had that as well). That's a much easier fix that you can do at home with the bike on the center stand. For that, you'd see oil around the boot where the transmission outputs into the swingarm.

Hope this helps!

natrab said:

If that is the case and it's engine oil, it's definitely worth a try to switch to dino oil and see if that causes the seals to swell a little and stop the leak.

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With respect, seals don't "swell". If they did, they'd leak more. If this leak is indeed caused by synthetic oil its because, in layman's terms, the stuff is so slippery it can get past the seal.

BC1100S said:

With respect, seals don't "swell". If they did, they'd leak more. If this leak is indeed caused by synthetic oil its because, in layman's terms, the stuff is so slippery it can get past the seal.

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Lucas oil has a product in its line that helps diminish oil leaks. True there is no actual “swelling” but the ingredient package helps the seal regain some of its pliability usually associated with age.
I have used a number of Lucas products with results effective enough that I can recommend them.
OM

BC1100S said:

With respect, seals don't "swell". If they did, they'd leak more. If this leak is indeed caused by synthetic oil its because, in layman's terms, the stuff is so slippery it can get past the seal.

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There is a whole pile of worms when you get into the term "seal swell" (as many oil and gasket companies use the term). No reason to get into the semantics of it in this case. The reason it is even a conversation is because anecdotally, switching from synthetic to dino has caused seals to work again in some fashion, which has led to it being a common thing to try if you have a minor leak, hence my suggestion.

natrab said:

There is a whole pile of worms when you get into the term "seal swell" (as many oil and gasket companies use the term). No reason to get into the semantics of it in this case. The reason it is even a conversation is because anecdotally, switching from synthetic to dino has caused seals to work again in some fashion, which has led to it being a common thing to try if you have a minor leak, hence my suggestion.

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I've never been big on semantics. I am, however, sort of fond of accuracy.

Omega Man said:

Lucas oil has a product in its line that helps diminish oil leaks. True there is no actual “swelling” but the ingredient package helps the seal regain some of its pliability usually associated with age.
I have used a number of Lucas products with results effective enough that I can recommend them.
OM

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Good to know.

semantics... is that an Israeli oil?

Pauls1150 said:

semantics... is that an Israeli oil?

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No, it was one half of the Semantics and Accuracy comedy team from the '80s.

The rear main seal was replaced on my 2012 while the bike was still under warranty.

There's a seal on the balancer shaft that gets replaced at the same time.

In my experience, some rubber compounds shrink in pure synthetic oil. Could be that conventional oil brings them back closer to what they were before.