Final Drive - Help diagnosing leak

[Kurt]

First of all... I'm a relatively new Guzzi rider.  V85TT 2023.  I changed the final drive (gearbox?) oil on my bike 2000 miles ago at about 1000 mile as part of the break-in service.  IU constantly checked for leaks and never noticed any.  I had read all about the issues folks have had with overfilling, etc. so I was very cautious about this.  Like I said, that was 2000 mile ago and no leak.

Yesterday I rode home from the campout in Suches and when I got home I notice the oil on my rear wheel.  Any ideas on what could have caused this this far past an oil change?

This was the first time I have ridden the bike fully loaded for camping and I have to say I rode hell bent for leather on a warm day.  I don't think that would cause the leak, but I have heard of stranger things causing problems on bike.

I guess what I'm hoping to hear, being a new Guzzi guy, is "Yeah, they all do that. Clean the tire, check the oil level, and ride like the wind".

 

[Dirk_S]

At least on the older small block final drive (V7 III and older), the pumpkin can spit out oil when the atmosphere changes. A day of rain can lead to moisture ingress and oil egress, or, if you ran the beans out of the bike on a particularly hot day, the vent does its job to prevent the internal pressure of the expanding gear oil from blowing the seals.

Because my bikes sit outside and I ride year-round in coastal New England, I deal with probably more change in atmospheric pressure, including humidity/moisture, than many others, and on a few occasions, I’d come back from a long day of riding with some oil pukage. Because of this, I’ve been advised that my conditions warrant the halved service intervals outlined in the owners manual.

I’ll leave any opinions to your particular situation to the better educated experts here.

[Kurt]

At least on the older small block final drive (V7 III and older), the pumpkin can spit out oil when the atmosphere changes. A day of rain can lead to moisture ingress and oil egress, or, if you ran the beans out of the bike on a particularly hot day, the vent does its job to prevent the internal pressure of the expanding gear oil from blowing the seals.

I’ll leave any opinions from this point to the better educated experts here.

Here's hoping you're right about the "running the beans" thing.  It's one month out of warranty.  I'm an old BMW guy and I don't remember them having a vent.  I just know their final drive would just die at the most inopportune time.  DAMHIK.

There is some oil on the tire, but not quite enough to make me think it's a blown seal.  I would expect more in that case.  But I'm a mechanical idiot.

[TN Mark]

If it’s not overfilled, it’s not over filled. Therefore, riding style, weather etc. should not be an issue. If these in fact are contributing factors, then, well, maybe it was over filled a bit. Regardless of what the Owners or the Service manual says.

Unfortunately, Piaggio seems to have a very difficult time referencing total volume and replacement volume. The entire rear drive may hold 500ml when they fill it at the factory. But that doesn’t mean the replacement volume is also 500ml.

I’ve read where Piaggio has screwed up on gas tank capacity, transmission capacity, engine oil capacity as well as rear differential (transmission) capacity versus the replacement (change) capacity. You seldom get ‘all’ the old oil out.

Those who know the V85 best will likely want to know what oil and how much went in.

There are many V85 owners here who’ll be along to help straighten this out for you.

PS - I really missed not being able to ride out to Blairesville to enjoy lunch with you guys.

[Dirk_S]

Here's hoping you're right about the "running the beans" thing.  It's one month out of warranty.  I'm an old BMW guy and I don't remember them having a vent.  I just know their final drive would just die at the most inopportune time.  DAMHIK.

There is some oil on the tire, but not quite enough to make me think it's a blown seal.  I would expect more in that case.  But I'm a mechanical idiot.

Not sure if you’re an ‘old guy into BMWs’, or ‘a guy into old BMWs’, or an ‘old guy into old BMWs’; I know the /2 models were not vented, but from the /5 to the last airheads of the 90s, the final drive was vented like these Guzzis.

[Kurt]

If it’s not overfilled, it’s not over filled. Therefore, riding style, weather etc. should not be an issue. If these in fact are contributing factors, then, well, maybe it was over filled a bit. Regardless of what the Owners or the Service manual says.

Unfortunately, Piaggio seems to have a very difficult time referencing total volume and replacement volume. The entire rear drive may hold 500ml when they fill it at the factory. But that doesn’t mean the replacement volume is also 500ml.

I’ve read where Piaggio has screwed up on gas tank capacity, transmission capacity, engine oil capacity as well as rear differential (transmission) capacity versus the replacement (change) capacity. You seldom get ‘all’ the old oil out.

Those who know the V85 best will likely want to know what oil and how much went in.

There are many V85 owners here who’ll be along to help straighten this out for you.

PS - I really missed not being able to ride out to Blairesville to enjoy lunch with you guys.

I had read a lot about that.  My understanding is that the quantity of oil in the final drive is 180ml but you only put in 160ml because 20ml of the old oil will remain after draining. I put in 160ml of Motul 75W140.

Thanks for the reply!

[Dr. Enzo Toma]

Not sure about the V85, but on the V7 the latest E5+ bikes seem to have the same final drive as the E5 but have a fill spec further revised to 130cc.
If it only leaked under these certain riding conditions, I would just clean it up and see if it happens again. If it happens again, can try refilling with 130cc.
My adventures in final drive leaks and that 130cc insight can be found here: https://wildguzzi.com/forum/index.php?topic=123836.0
Is it leaking where the wheel meets the hub, or from the small drain hole in the swingarm? My experience is that overfilled results in leaking where the hub and wheel meet, drain hole leak for me indicated a mechanical & seal failure.

[yrunvs]

I wouldnt doubt that the seal near the weep hole is the problem. Sometimes water can ingress into the hole and cause problems other times over filling is the culprit then again just a poor oem seal to begin with may be the issue. Wipe the bike clean and observe that weep hole for any more leaking and if their is more then probably the seal needs replacing.

[malik]

Try blowing a mist of talcum powder over the suspect areas of the bevel box to determine where exactly the oil is coming from. Could help the diagnosis.

[Kurt]

UPDATE

I drained the gear oil into a graduated cup and 170ml came out.  Obvious overfill.  Gonna put back all but 10ml back into the drive and see what happens.

[Dirk_S]

UPDATE

I drained the gear oil into a graduated cup and 170ml came out.  Obvious overfill.  Gonna put back all but 10ml back into the drive and see what happens.

Assuming the color wasn’t milky?

[Kurt]

Assuming the color wasn’t milky?

No.  It was actually still pretty much blue.  No water contamination was noted.

I was just about to add that I drained the oil cold.  I'm going to let it drain overnight. Not sure is gear oil expands or not. Probably won't make a difference since I don't normally warm up the new oil before refilling anyway. 

[mhershon]

Kurt, I just changed the fluid in my V7 series one's final drive. It leaked thousands of miles ago and I shipped it to CT and had Hamlin Cycles repair it. I measured the amount that drained from my final drive, 150cc, and replaced it with the same amount. I've had great luck with that amount. By the way, I replace the gear oil via the level hole, not the breather hole. Saves lots of time and agony. On second thought, maybe V85s don't have a level hole... My fluid came out black and there was a bit of crud on the drain plug magnet. I made up a breather with a hose that goes up under the bike's seat. You use brake hydraulic fittings to set that up. Available via Amazon. Eliminates worries about that mysterious breather.

[Kurt]

Kurt, I just changed the fluid in my V7 series one's final drive. It leaked thousands of miles ago and I shipped it to CT and had Hamlin Cycles repair it. I measured the amount that drained from my final drive, 150cc, and replaced it with the same amount. I've had great luck with that amount. By the way, I replace the gear oil via the level hole, not the breather hole. Saves lots of time and agony. On second thought, maybe V85s don't have a level hole... My fluid came out black and there was a bit of crud on the drain plug magnet. I made up a breather with a hose that goes up under the bike's seat. You use brake hydraulic fittings to set that up. Available via Amazon. Eliminates worries about that mysterious breather.

Yeah, the V85TT has a level hole but I have been told not to trust it.  Measure the oil, don't just fill it until the oil dribbles from the hole. I have a centerstand and the level hole may or may not be on the level.  I can rock it back and forth on the stand and that would change the position of the hole.

Like I said, I'm new to Guzzi ownership.  I mean I've had this one for two years, but Helene really put a cramp in our riding here last year.

[Dr. Enzo Toma]

I would hesitate to call it a "level" hole for that reason. On the V7 850 at least it is not a fill-to-spill and will let you put at least 200cc into it, which is far beyond the spec. Per the workshop manual it is the "filler" plug/hole though.

[faffi]

If you use the fill hole as a guide, the bike must be level. If placed on the side stand, the lean of the bike will allow overfill. How much, I cannot say, but definitely some.