V7 850 final drive leak while touring

[Dr. Enzo Toma]

I left Colorado this morning on my 2022 V7 850 Stone and made it into Kansas where I noticed oil on the rear wheel. I was hoping it had been overfilled. I had recently had the 12.4k mile service done, so I phoned the service department and described that the oil was seeping from the pinhole on the bottom, was told that it was likely just overfilled which eased my mind so I cleaned it up with brake cleaner and rechecked in 100 miles at the next gas stop, where unfortunately it was made clear it's not an overfilling issue. I'm guessing a seal has failed. I was shooting for Chicago by Monday, but I'm thinking tomorrow I will ride to an auto parts store, then drain and measure the final drive oil to have an idea of the loss, refill it, and ride ~200 miles to get a hotel near Harpers Moto Guzzi in Missouri so I can get in there at open on Monday and hopefully get something scheduled.

From what I'm reading in the service manual and online discussions, there's no way to check the final drive oil level other than draining it and measuring what comes out. Is that correct for the V7 850? The spec I found is 160cc of 75W-140 for a drain and replace (180cc from dry). Any other suggestions or possible roadside solutions before I limp it to Missouri? Thanks in advance.

[Dirk_S]

If it doesn’t say in the owners manual for the E5 models, previous small block manuals (along with multiple other shaft-drive motos like the BMW boxers) note that the pumpkin should be filled through the side until oil starts coming out, so you could simply open up the side port  screw and see how much comes out. Keep in mind—the pumpkin should be as level as possible for this to be accurate.

I’m surprised to see they finally added a moisture drain port at the rear of the swingarm.

[Dirk_S]

Sorry, one other note—if you’ve done multiple long days in various atmospheric conditions, including hot, cool, humid, dry, rainy, elevation changes, etc., it could be that some moisture was drawn into the pumpkin, making it overfilled.

[Vagrant]

Just 5 ounces is all you need. Never fill to the level check becease it isn't one. 75-140 or similar. I'd also pull the vent on top and see if it works.

[Dirk_S]

…Never fill to the level check becease it isn't one…

Guzzi sure thought it was for the small blocks—at least up until the E5 bikes. Most of the pre-E5 manuals I’ve looked at show this:





They changed the instructions on the E5 bikes to a smaller volume to account for the residual oil left in the box (similar to how engine oil change is considered with or without the engine filter replacement:





I definitely feel that was a wise decision. Seems like every other dealer likes to overfill them.

I would imagine it could still be used for checking the level, but I’ll defer to stronger opinions.

[Vagrant]

Lots of old threads here and elsewhere about leaking V7 rear ends. I've had two. Both cured with 5-5.4 onces.

[Kev m]

I've heard this myth that Guzzi rear drive fluid plugs are NOT level plugs. I've heard it so much I've always measured what I drain and what I replace.

Thing is, everytime on various different Guzzis I've owned the measured amount comes more or less up to the base of the threads of said plug.

I think it's another case of much ado...

[Dr. Enzo Toma]

I was too quick to dismiss it being overfilled. It just seemed like way too much oil for too long to be a little overfilled. Now, it seems that's all the issue was. I pulled the fill bolt out (9 o'clock on the pumpkin) to see if that would give any indication of the oil level, and with the bike on the side stand a dribble of oil did start to flow out and then it stopped. Then I pulled the drain (6 o'clock on the pumpkin) I ended up with a total of just over 200 ml out! Referring back to the service manual, which @Dirk_S also posted a snippet of to this thread, the drain/fill volume is 160 ml, while the volume for assembly from dry is 180 ml. So it was over even the maximum figure. Checking the breather was also an appreciated suggestion, though I wasn't able to. On the V7 850 there's a rubber cap over it, which I was able to remove, but then the breather bolt itself isn't a straight shot down into the housing so I couldn't get a socket on it, and the wrenches I'm carrying nearly fit it, but the housing got in the way of being able to turn it. Because of that I wasn't able to remove it for inspection, and the more I looked at it the more I worried that if I did get it loose, would it be possible to drop it inside of the housing? I couldn't get a good look in there to see. The underside of the rubber cap on the breather looked fairly clean though so I'll hope it's not clogged.

Looking at the maintenance schedule table, the final drive oil's first replacement is recommended at 18.6k miles, I had just got the bike back from 12.4k mile service + new tires. So what I suspect may have happened was that while changing the rear tire, the mechanic got the idea to top off the final drive oil. I say top off because my visual read of the oil, and the swarf that was on the magnetic drain plug, don't match with this having been drained within the past thousand miles. I didn't test the physics of side stand vs upright for the fill hole level, but I suspect that if you were to use (misuse?) the fill hole as a fill-to-spill hole or weep hole, the pumpkin would hold more with the bike upright and how a shop would have likely had the bike while working on it. Especially since this bike had been losing a visually concerning amount of oil, and then still produced 200 ml of oil. If it were a weep hole, wouldn't that make it easy to get the measurement right? If the spec was for 160 ml and any more would dribble out the fill hole as a weep hole, then how would someone manage to overfill it? I'm convinced it's not a weep hole, but was used as one. Since having the last service + tires done, I've mostly ridden the bike locally and not very high speed, 65-70 mph for a short stretch between towns, which may be why I didn't notice the oil seepage until a couple hundred miles of highway riding. I really think this issue was caused by the most recent service + tire change, because it doesn't seem realistic that the pumpkin would have had 200 ml+ in it since the prior service just over 6,000 miles ago, between which I did the reverse of this leg of my trip having ridden the bike from IL to CO in April.

So for anyone coming across this thread in the future, know that it's possible to way overfill the final drive oil. 40 ml + overfill. I also think that a little gear oil may go a long way in terms of visual splatter on a rear wheel. I was really expecting to find the oil level half empty and a failed seal, instead it had sprayed the rear wheel for a few hundred miles and still had 200 ml to go.

Since draining and refilling with new oil, there's been a slight dribble out. I likely did not have it warmed up enough or the patience to hold the bike upright long enough to properly drain it, but now a couple hundred miles later into the trip the last gas stop I checked and it was just a slight damp spot around that pinhole on the bottom. Here's hoping that's the end of it.

My big takeaways are: as usual RTFM, this forum is one of the best sources of Guzzi info out there, just be sure it's applicable to your model and generation, and I really need to stop paying shops to make mistakes that I'm just as capable of making on my own. I was very hesitant to take the bike into the shop for the last service and oil change because I had it into that shop for the first service at 900 miles and they had scratched it up and botched some wiring installing the OEM USB accessory under the seat. I quickly got over the bike being scratched as I set off on a tour soon after that and the bike was no longer "new" to me. I caved and brought it back to them because I wasn't equipped to pull the rear wheel and change the tire. I'll have to correct that for next time I guess.

My trip continues, I skipped Harper's and should be in Chicago on Monday night one day off schedule. I'm making the best of it and spent some of today visiting a friend along the route since I already called off work tomorrow, and tomorrow I'll have another more leisurely day and revisit some of the Mark Twain sights near the Mississippi. I'll have to start another thread to document it, but this is the first leg of a coast to coast trip I'm taking. If all goes well, the plan is CO to IL, stay in IL for a bit, continue on to the coast in NC, stay there for a bit, then west to the OR coast, stay there a bit, then back to CO. I'm on the crew for a team in the Motorcycle Trans Am event so for NC to OR I'm on that route.
https://motorcycletransam.com/2025-route/


V7 850 e5 final drive breather rubber cap




Breather bolt with rubber cap removed




My wrench fit, but not enough to turn it enough to break loose




Weeping out the fill hole




The 200+ ml that came out, which is after it had already coated the rear wheel a few times over




This morning's workshop, an O'Rielly's parking lot in walking distance of a hardware store and an AutoZone, which worked out great for finding all the supplies I needed.




Part of a funnel I bought at one store, fitted to a hose I bought at another store. None of the flex funnels had a small enough tube to fit into the fill hole, so I came up with this (and am keeping it on the bike for now).




A photo of my goose and the Atlas 9 giant in Kansas City. I often detour to roadside attractions such as muffler men for a photo, and found out about this new non-muffler man giant from the company that restores the muffler men, "American Giants". Atlas 9 is going to be some interactive art exhibit experience similar to Meow Wolf, but it isn't set to open until October.

[guzzisteve]

I would get a centerstand. The breather comes out if you grind down a deep well socket on the outside to make it thin wall.

[Vagrant]

I haven't had any experiance with the v7-850 yet. But now that I see it's a v85 rear end you still have too much oil in it. They started at 180. Then went to 160 and are now at 130 for the refills to stop the leaks. Personally I did 140 when I did my 25 V85 a month ago. If I was you I'd carefully pull the drain plug when ice cold in the am and let out 20 more assuming you did 160. A bit messy but I think you troubles will end.

[yrunvs]

I'm sure most of you know but for those that may not......pertaining to that breather cap with the yellow paint on it. It's just a cap and not ment to be unscrewed the bolt part is down further and that's where the unscrewing is done.

[Dr. Enzo Toma]

I installed a H&B center stand on the bike earlier this year but was disappointed to find that even with luggage off the bike, I can't get it onto the center stand without assistance so it hasn't been much use to me while on the road. I wonder if there's some technique to it that I'm missing, as I struggled to put a modern Gold Wing on the center stand before attempting it with right foot pointed slightly toward the rear wheel. I weigh about 135 lbs before gear, so don't have that to my advantage for leverage.


Good to know about 160 ml still possibly being too much! That explains the much less significant dribble I observed right after. Hopefully all this oil seepage hasn't caused any issue with the seal.

I now see what you mean with the breather cap comment. Looking at the parts fiche the black rubber insert is labeled as a cap and the part below it with the marking paint is labeled as the breather plug, below it is a gasket. Interesting that the breather plug would have a second cap, but I see see the larger bolt head below it that would be used to remove it. While I'm in Illinois this week I'll pick up a deep well socket and grind it down to examine that and keep in the bike's kit. I appreciate the tips! Have learned a lot already.

[CanonVanagon]

I recently changed the final drive oil in my V7 850 with 160 ml (cc) and after 700 miles I haven't had any leaking.

[Vagrant]

I wouldn't mess with the vent now that the issue is almost gone. Just enjoy the trip. Next tire change will be fine. FYI, there have been no issues since they hid them unlike early V7 units.

[yrunvs]

A further mention about the breather and that is it's a two way breather it closes when internal pressure is normal and keeps water and dirt out and opens to relieve internal pressure so there is a possibility that it could malfunction and create above normal internal pressure that may or may not lead to a problems. If you do ever remove it to check if it's operational you can blow into the non painted end and it should open up while sucking it should plug up.

[Dr. Enzo Toma]

Documenting this here in case it's useful to anyone else who encounters this issue in the future, but unfortunately this ended up not being a simple matter of too much oil in the bevel box. After having the seals inspected in Portland, Oregon with no issues observed, and then having the input shaft seal replaced (though it appeared fine) in Fort Collins, I just picked up the bike back from having the final drive replaced entirely and am hoping for some trouble free miles on my Moto Guzzi now.

The input shaft seal still looks good with no visible damage to it. This was my first shaft drive motorcycle so I'm no expert here, but my theory based on observation is that the pinion gear making too much contact on the tip. How do you adjust the depth of the pinion into the ring? I see a washer that may act like a shim there. Funny enough, the workshop manual I have (PDF) for my bike is in English, but switches to Italian when providing the instructions for checking the backlash here! In English though it does state

"SINCE THE BEVEL GEAR IS A SAFETY COMPONENT, IT IS STRICTLY FORBIDDEN TO PER-
FORM ANY PINION/SPROCKET CLEARANCE ADJUSTMENTS FOR THE ENTIRE DURATION OF
THE COMPONENT'S SERVICE LIFE. IF THE CLEARANCE IS NOT WITHIN THE REQUIRED TOL-
ERANCE, THE ENTIRE BOX WILL HAVE TO BE REPLACED."

I think this was out of adjustment on my bike. If it wasn't out of whack since new, then it may have been caused at one of the two rear tire changes when the rear wheel and bevel box would have come off. I think that issue of improper contact from pinion to ring gear chewed up the teeth, and that either the poor contact or heat may have over pressurized the pumpkin and caused oil to pass by the input shaft seal. Does that sound plausible?

It's a mystery to me, and hopefully fixed now since the whole unit has been replaced, so trying to diagnose it is just to satisfy curiosity. I don't know that anything I could have done would have prevented this, but am very curious of others' thoughts.







"COMPLETE TRANSMISSION BOX" was $789.98 and they reduced the labor to a half hour since this was a return issue from them having replaced the input shaft seal in October, the damage with tax came out to $935.32

[chuck peterson]

Dang, sorry for your troubles

Re using the center stand, it’s more momentum rearward than lifting upwards by strength. Try that

[ridingron]

"...  While I'm in Illinois this week I'll pick up a deep well socket and grind it down to examine that and keep in the bike's kit. I appreciate the tips! Have learned a lot already."

Before you buy a new socket and grind on it, ask about a thin wall socket that size. The cost difference is probably small.

[Dirk_S]

"...  While I'm in Illinois this week I'll pick up a deep well socket and grind it down to examine that and keep in the bike's kit. I appreciate the tips! Have learned a lot already."

Before you buy a new socket and grind on it, ask about a thin wall socket that size. The cost difference is probably small.

Looking at the photos, I don’t even see how a thin-walled socket can fit onto the breather cap while the wheel is still installed. Looks like the hub’s lip interferes too much.

Has anyone removed a final drive breather bolt on a V7 E5, V9, or V85TT with the wheel still attached?

[Dr. Enzo Toma]

Looking at the photos, I don’t even see how a thin-walled socket can fit onto the breather cap while the wheel is still installed. Looks like the hub’s lip interferes too much.

Has anyone removed a final drive breather bolt on a V7 E5, V9, or V85TT with the wheel still attached?

That is what I concluded when I tried a 16mm(?) narrow wall socket. It did not fit with the wheel installed. With the wheel off unless you put an open ended wrench on it and struggle with that, a narrow wall socket would still be required to fit as you can see from the small gap of clearance in this photo of the removed failed final drive unit.

[Dr. Enzo Toma]

Photo pointing more specifically to the clearance I'm referring to where a thin wall socket is required.

[MikeP996]

Re Center stand:  After acquiring my '21 V7 Special some months back I ordered the Moto Guzzi centerstand and installed it.  The bike is the EASIEST of all motorcycles I've owned to put on the centerstand.  Obviously the MG stand must be designed a bit differently than some other stands but it really works great!!!

[Dirk_S]

Photo pointing more specifically to the clearance I'm referring to where a thin wall socket is required.

The pre-E5 V9 models, while using that newer final drive casting (or extremely similar), still used the older style dog plate, which apparently is smaller, because I could easily place an open-end spanner on the breather cap.

Guzzi just keeps making it harder to work on our own bikes.

[MikeP996]

Sounds like MG want folks to have all work done by a dealer...but there are hardly any to be found!  ;)