New FD seal leaks do you know why?

[pablo666]

Ok here's the deal: I replaced FD bearing, new large o-ring and new FD seal. No obviouss damage to case etc, all cleaned and plimmed up. Went for test ride about 20 miles and all ok. Two day trip to wales, and on the 2nd day, half way home I get a leak. I assume that the drain plug wasn't nipped up tight enough so nipped it up a bit and carried on. By the time I got home, leak was worse and all over wheel and tyre.

Cleaned up and torqued drain plug refilled oil. 50 mile tester.. no problems. Left for 3 day trip to France (bout 1000 miles).

On day 3 of French trip, leaks again. On Ferry I really nipped up the drain plug, thinking either shaken loose or torque not good enough due to stretched bolt etc. Newhaven to Northampton and the leak gets so bad that I leave a puddle of oil on the ground at a Northampton service station.

On very close exam, this is coming from the new FD seal. Cleaned up filled up fresh oil. Nipped up (well) drain plug with new crush washer (again). Not leaked for a week of commuting.

My guess is that lengthy journey means hotter oil that leaks past a seal that for some reason isn't doing its job.

Have I put the seal in wrong? Is there a technique? Is it a faulty seal? Can they be easily damaged?

Suggestions please?

 

[Paul G (BHT)]

Do you have ABS on your GS?

 

[Steptoe]

Suggestions please?

The output flange has a shiney part where the old seal was located and a cruddy part where all the crap over the years has roughed up the surface.

Do you replace the seal at the same deptch as the previous seal ? Is the new seal on the cruddy part ? If so knock it in a touch. Although it may have already been damaged, in which case a new seal wil be needed.

 

[pablo666]

Not ABS, Steptoe may have hit nail. I knocked in seal as far as I could tap it in.

 

[littleredrooster]

Reasons for new seal failure - choose whichever is most appropriate:

1. Assembled dry
2. Assembled on to a corroded or rough shaft
3. Assembled with a foreign body inclusion (dirt)
4. Mechanically damaged during assembly ('caught' the fine edge of the seal on something)
5. Excess pressure from within (above design limit)
6. Excess heat
7. Excess clearance in related bearing - either radial or end-float

Erm...I'm sure there's a number 8 but can't remember.

 

[sockpuppet]

Not ABS, Steptoe may have hit nail. I knocked in seal as far as I could tap it in.

That's too far. I made that mistake first time I did mine and had to use another seal. Its flush with the face i.e. where the crud mark is.

Go to your local bearings shop for the seal. Should be £2.50 as opposed to £17 from BMW.

 

[harry]

Could you have over-filled it?