Boxerworks.com

mkj wrote: ↑Mon Sep 25, 2023 3:55 pm Oh lucky me, I too have just attempted the replacement of my rear main seal and I may say with out success. I tracked it down to a groove on the fly wheel boss, I have not cured the leak yet as I put a second hand flywheel in, on an already used seal. My seal came on a plastic former and had cartoon instructions . The instructions say to leave the seal in place for 4 hours before starting the engine, chamfer nothing but get a thing strip of fine wet and dry paper and clean up the surface where the seal runs then polish it with metal polish get it as shinny as you can. I have manged to polish the grove out of my original flywheel and will refit it with a new seal come winter.

Hi, well I have been so busy here in NZ that I only started pulling the gearbox out last weekend so I have not done it as yet but i do know I have not got a wear grove in the flywheel, I did read somewhere about polishing the seal face on the flywheel, the last seal I fitted had a plastic former in it but for the life of me I cannot see why as it was a normal double lip seal, the new seal is very different and has only one lip and matches what is mentioned in a service bulletin that was sent to me by another member, hopefully I will get it finished this weekend and it will be ready for summer.

Hope all goes well for your's

In order to avoid embarrassment I now pack a little oil absorbent workshop blue roll underneath the gear box to soak up the oil and for 100 miles or so no drips. Just like an old lady.

So last weekend I finally pulled the bike apart and got to look at the rear main seal, yes it was leaking so out it came, to my amazement the seal lip looked fine but had gone brittle and inflexible so am thinking this seal was old stock and had aged.
New seal (BMW OEM) is in and gearbox installed I will finish it off this weekend as need to get it out as it'd blocking access to my F800gs that I have just sold.

Am making painfully slow progress on getting my bike back together due to health issues, however after pulling out the old rear main seal I carefully checked the new OEM item prior to fitment, on the seal it had a arrow for shaft rotation (anticlockwise) the seal I fitter from a non OEM supplier had none.
Now I have seen this before on the likes of Honda Car engines with Timing Belt Drive to the camshaft from the crank all the seals have an arrow with anticlockwise rotation arrow (they run Anticlockwise from the timing side), I have had many of these engines come in leaking oil because people have put in the wrong seals, usually if there is no arrow the seal is meant for a clockwise shaft rotation.

So beware you may get caught out as I did.