R80/7 Rear Main Seal Leak

[jackonz]

Following the re omission of the R80 and now clocked 500 miles am going to take the bike off the road as the rear main seal has started to leak, during the re omission I replaced the seal and O Ring but it has not cured the issue that the bike came with.

So either the seal I was supplied is not up to the job or I did something wrong, any suggestions before I go ordering parts and getting it wrong again.

[RPGR90s]

Did you verify that it's motor oil and not transmission fluid?

There's three possible areas of leakage at that location.

rear main
oil pump cover o-ring
transmission input shaft seal

[melville]

Did you verify that it's motor oil and not transmission fluid?

There's three possible areas of leakage at that location.

rear main
oil pump cover o-ring
transmission input shaft seal

Yes, I've replaced the first two and realized during the job that it was actually the third. Not sure why I didn't give the oil the sniff test when I took it apart. I use a gear oil with a distinctive smell.

[jackonz]

Did you verify that it's motor oil and not transmission fluid?

There's three possible areas of leakage at that location.

rear main
oil pump cover o-ring
transmission input shaft seal

Yes, I've replaced the first two and realized during the job that it was actually the third. Not sure why I didn't give the oil the sniff test when I took it apart. I use a gear oil with a distinctive smell.

Yes it is engine oil as I too use a gear oil with a distinctive smell and it's not that, I also replaced the the O ring on the oil pump cover and the transmission input shaft seal.
One thing nagged at me and now am now kicking myself I did not purchase the tool that was on offer from BMW Motorworks to fit the rear main seal when I purchased all the parts from them, now I wonder if that's the cause as in its installed too deep or not deep enough, to add to it they have 2 versions of the seal on offer and I chose the more expensive item as it was supposed to be an improvement over the original, the other as I recall was a pattern item.

If I knew what the correct depth the seal should be installed I could make a tool in the machine shop at work but I need a drawing or info on the correct position the seal should be from the face of the engine block.

As we say here Shit happens

[gspd]

The rear main seal has to be installed bone DRY (and the flange perfectly clean) or it will leak like a sieve as soon as the engine is started. The correct depth is flush with the case. No special tool required if it's tapped in squarely.
I've seen one or two oil pump covers with almost invisible hairline cracks around the screw holes cause leaks in that area.
If in doubt, start the bike and check for leaks before re-installing the transmission.

[jackonz]

The rear main seal has to be installed bone DRY (and the flange perfectly clean) or it will leak like a sieve as soon as the engine is started. The correct depth is flush with the case. No special tool required if it's tapped in squarely.
I've seen one or two oil pump covers with almost invisible hairline cracks around the screw holes cause leaks in that area.
If in doubt, start the bike and check for leaks before re-installing the transmission.

Hi, thanks for the info it's not a big leak and the seal was installed dry and the case was very clean, after 500 miles I have a small puddle of oil around 25mm, it's hacked me off no end.

I will give it all a good clean and see if it gets worse but I will pull it apart sooner rather than later and also crack test the oil pump cover plate.

Many thanks

[Airbear]

Phil, here's a simple tool that will pull the RMS to its rightful place:

RMS.jpg (83.86 KiB) Viewed 1819 times

[Zombie Master]

Were the seal OEM fresh, or old stock, non OEM? If the installation was wrong then you will have to try again. Ive seen this product work wonders on old seals. it a polymer that can recondition seals.

AT-205 ATP Re-Seal Leak Stopper

So if the seals you got were old and hard, who knows?

[jackonz]

Phil, here's a simple tool that will pull the RMS to its rightful place:


RMS.jpg

Thanks Charlie, how thick did you make it?

[jackonz]

Were the seal OEM fresh, or old stock, non OEM? If the installation was wrong then you will have to try again. Ive seen this product work wonders on old seals. it a polymer that can recondition seals.

AT-205 ATP Re-Seal Leak Stopper

So if the seals you got were old and hard, who knows?

Hi, seal was brand new from BMW Motorworks in the UK, as for this product am not that keen on using this type of product but thanks anyway.