Need help! Small oil leak MG Nevada 750

[Shlugengruven]

Hey all - I'm new to the Moto Guzzi world - just bought a 2005 Nevada Classic 750 with about 4500 miles on it. I noticed a small (15 drops) oil leak each time I start it up. I'm attaching a couple pictures and video of the leak location, but it is the bottoms rear of the engine block about 3 inches above the drain valve. After about 5 minutes at idle it stops leaking and does not leak again.

Any idea what the cause could be?

http://ibb.co/eysvQa
http://ibb.co/i40RWF

^hopefully the photos show up...

[pete roper]

Is it gear oil or engine oil? If gear oil it'll probably be a weepy input shaft seal, if it's engine oil probably rear main seal.

[fotoguzzi]

Gear lube will have a distinct odor.

[neverquit]

My bike had oil all over the place and I traced it back to that hose connection you see in your pictures.  The fitting in the block was loose, I snugged it up a bit and now it is fine.  The wind while riding was causing the oil to spread all around the lower engine, starter etc.

[sib]

My bike had oil all over the place and I traced it back to that hose connection you see in your pictures.  The fitting in the block was loose, I snugged it up a bit and now it is fine.  The wind while riding was causing the oil to spread all around the lower engine, starter etc.

I had exactly the same problem, and solution, on my '13 Stone.

[Muzz]

Oil is clear, so unless you have only just changed your engine oil.

Right at that point where the oil is dripping from there is a small slot in the bell housing. This is to drain out any oil, which can be from either the engine or the gearbox, rather than having it soak the clutch. As Fotoguzzi has said, the gearbox oil will have an acrid smell. I cleaned the underside of the bike, went for a decent ride, and then parked it over a white paper towel. Helps identifying the culprit. If it is not the offending hose and it is definitely coming from that slot, then the gearbox will have to come off.

If that is the case the offender will be either the rear main seal for engine oil. and either (or both) the main gearbox seal and/or the pushrod seal O ring.

Hopefully it is the hose..........

Edit: your first shot shows a helluva lot of oil for it to be a seal.

[pehayes]

Someone else please check and correct me if I am wrong.  Guzzi never used a button head screw to fasten the transmission to the engine.  Thus, evidence that someone has likely had this transmission off previously.  My info is on early smallblocks, so perhaps changed for this later version??

BTW, the seal for the clutch pushrod is not an o-ring, but a tiny, normal-shaped seal.  There is an o-ring in the clutch pushrod system but that is for the outer body at the back of the transmission and wouldn't leak here.  The forward 'true seal' for the clutch pushrod resides at the aft end of the stubby transmission input shaft.  Bell housing has to be removed from the transmission to access that seal.  Again, info from early version smallblocks but I doubt the design has changed.

Patrick Hayes
Fremont CA

[Muzz]

Breva is all in=hex cap screws.