Final drive venting gear oil

[guzzifan]

The final drive on my Convert is venting gear oil out of the top fill plug.  I'm sure I could fix this with a little Teflon tape, but I'm curious why it feels the need to vent?  I filled it with the amount specified in the manual...

will it find it's own comfortable level at some point, or will it blow it out until it is empty?

Will sealing the top fill plug with talon tape cause other issues...will it vent out a seal instead?

Bike is new to me...first ride after being resurrected from a basket case.

Thanks all.

[tris]

I suspect that you need to "burp" it
Take it for a ride to get the transmission good and hot.
Stop and crack the fill plug open to let the pressure out and retighten.
My Cali 1100 used to do what yours is  until I learnt this trick from this forum

[rodekyll]

Don't block the vent.  It's doing its job.

Recheck your fluid level.  You could have overfilled or fluid may be migrating down the swing arm from the gearbox.

What lube is in there?

Leaking at the vent is neither normal nor common.  Something is happening.

[pehayes]

Yes, drain and measure.  Could be transmission gear oil migrating down the shaft drive.  Transmission output shaft seal may have gone bad.  Tell us what specification you are using.  IIRC, it should be 230cc of gear oil and 20cc of a moly additive for a 250cc total.  I have seen people put in 250 + 20.  It is not normal to need venting.  What gear oil did you use?  Some brands are more prone to foaming than others.

Patrick Hayes
Fremont CA

[Charles in Lake Charles]

You may need a new 20mm aluminum sealing washer.

[John A]

generally the pressure in the rear drive pushes a small amount of oil up the driveshaft, if you are lucky. some do it more than others.

[guzzifan]

Every seal on the bike is brand new...this was mile 3 after a fresh overhaul on every single part.  Rear drive was given exactly 230 + 20 for a total of 250 of pennzoil 80-90 wt.  New sealing washer on top fill plug...there is no specific vent per se.  After a run a bit of oil oozes out of the top fill plug and runs down the side of the housing.  There is no oil in the swingarm boot and the rear of the trans output is perfectly oil free.

Burping the drive...is this normal?  I'll give it a go.

[oldbike54]

 Yes , it is too full , so it is venting , because it needs to be burped 

 Dusty

[Muzz]

Does the rear drive on those use 80/90?

The B750 uses 80/140, Would have thought the big block would use much the same. Gearbox is 80/90.

[Tom]

 :1:  I do that on all my Guzzi bikes.