slight rearend leak question

[Hotrodwing]

Hey guys I noticed after the last few rides I am getting a little seeping from the rear-end vent hole.  Any thoughts?   Was thinking pinion cup seal.  I replaced pion cup and seal about 5 yrs ago

[Valker]

Overfilling is about the only thing that can cause that. Possibly too light an oil.

[Hotrodwing]

Thanks Valker been using the same 90wt syn oil for years no issues, may have overfilled when I changed it end of last season. 

[Valker]

Thanks Valker been using the same 90wt syn oil for years no issues, may have overfilled when I changed it end of last season. 

Stood up level, the fluid should just dribble out the big fill hole -that's full. I add a bit more with it on the side stand. Not until it runs out or it'll leak out the vent.

[Chrisj CMA]

Thanks Valker been using the same 90wt syn oil for years no issues, may have overfilled when I changed it end of last season.  

Trying to get a complete drain while it's still on the bike might be hard. Did you fill till or overflowed at the fill hole or did you pour in the measured 150cc

For this very reason plus so there's no mess from over flowing. I change the gear oil when the drive is off the bike. Get a complete drain until at least 150cc comes out and then add 150 of fresh

[Hotrodwing]

Thanks Chris .  I just drain and fill while on bike. I believe I filled it till it dribbled out while on the side stand .  I m sure this was the issue.  Next tire change I will pull rear and drain and fill with the recommended 150 cc

[h13man]

Overfilled and/or not using Hypoid gear lube.

[Hotrodwing]

Thanks guys looks like I must have filled while on side stand.  put bike up right in chock and removed filler only to have quite a bit drain out.   All good now.  I  must have been in a hurry before my trip last year and just overfilled.  Thanks again