Seating the rear main seal on a Griso 8v

[JWD]

I'm in the process of replacing a leaking rear main seal on my 2009 8v Griso. I noticed that the original (leaking) seal was seated flush with the face of the flange. But when I went to tap in the new seal it recessed about 1/8 of an inch and it looks like it can go another 1/8 before bottoming out in the groove. I did a quick image search on google and every one I saw had the seal flush with the flange. I couldn't find anything in the manual about it. Anyone know whether the seal should be set flush or seated fully in the flange?

[Bill Hagan]

Even tho, of course, I haven't a clue as to the answer, I find this sort of question fascinating so I went to the service manual and wandered around.  Surely it must address this.

Was surprised -- as were you -- that it seems of no help despite lots of other useful pix.

Looking forward to responses from Pete and others who know what they are doing.  Not enough grappa to get me to ta cole such a project.  Always impressed by the courage of folks like you.  I am happy when I can R&R fluids, etc.

Buon fortuna.

Bill

[Vasco DG]

No, the seal should only be pressed in until flush with the outer face of the flange. If you use the bearing itself as a register the oil escaping from the back of the bearing can't drain back to the sump and will blow the seal immediately you start the engine.

Are you sure it was the seal leaking? Early 8V's had a bad batch of flanges that weren't machined properly and they leak around the oil feed dowel due to a combination of the dowel not sitting deep enough and the two bottom flange bolts being too long. If you remove the flange you do NOT use a gasket when you re-install it. Just a thin smear of threebond around the flange.

Pete

[JWD]

No, the seal should only be pressed in until flush with the outer face of the flange. If you use the bearing itself as a register the oil escaping from the back of the bearing can't drain back to the sump and will blow the seal immediately you start the engine.

Are you sure it was the seal leaking? Early 8V's had a bad batch of flanges that weren't machined properly and they leak around the oil feed dowel due to a combination of the dowel not sitting deep enough and the two bottom flange bolts being too long. If you remove the flange you do NOT use a gasket when you re-install it. Just a thin smear of threebond around the flange.

Pete

Crap. So I guess I'm going to need another new seal. And after waiting more than a month for all of the parts to come in.

I'm pretty sure it was the seal, but I measured the two bottom bolts and the gap was right at 8mm when they bottomed out. I couldn't find any 22mm replacements, so I'm hoping a 20mm will still provide enough threads.

Also, I got an oversized o-ring from Moto International. Do you still recommend leaving out the gasket even with the oversized o-ring?

[Vasco DG]

Crap. So I guess I'm going to need another new seal. And after waiting more than a month for all of the parts to come in.

I'm pretty sure it was the seal, but I measured the two bottom bolts and the gap was right at 8mm when they bottomed out. I couldn't find any 22mm replacements, so I'm hoping a 20mm will still provide enough threads.

Also, I got an oversized o-ring from Moto International. Do you still recommend leaving out the gasket even with the oversized o-ring?

I have no experience of this fix. All I can offer is the sollution suggested by the factory. The seal should be easy enough to get, try MG/Harpers, whoever if your local dealer has problems getting one.

Pete

[jlburgess]

I had the same year model Griso and it was in the shop for over six months trying to get that problem diagnosed and rectified. As Pete said the two lower bolts are too long you can probably stick a feeler gauge in behind the bolt heads.  mine came loose after sixteen thousand miles and started slowly dripping oil out of the flange. I'd highly recommend getting a new rear flange as well like Pete said it's cheap insurance. be very careful about reinserting the clutch push rod in the correct manner. The dealer did mine and it started spinning and it sounded like a Ducati dry clutch. It will end up milling a hole into the pressure plate causing another complete tear down and replacement of the pressure plate and burnt up clutch.  Good luck!

[lucian]

Awe come on, I don't have time to start worrying about this , I'm to busy worrying about my flat tappets, and my carc drive going tits up.  ???

[mtiberio]

I have no experience with the Griso, but on a regular 2 valve motor, I never push the seal below flush with the bearing. There is a gap behind, as someone stated, that catches oil for drain back. If I had a chronic leaker (from the seal crank-interface), I might try a little deeper just to get the seal to ride on a fresh part of the crank. I hadn't heard about the lower two flang bolt issue. Was making these 2 holes "blind" guzzi's answer to the thru hole oil leakage of earlier blocks? (requiring sealant on the lower two bolts)

[Vasco DG]

You don't have to waste time worrying about it. Only a few early models were affected, it's by no means universal. There are so many scare stories available on the web you'd think they were all fragile hand grenades! I have heaps of customers who have had precisely ZERO problems with their 8V's. Just ride it and enjoy.

Pete

PS. Mike, the case is substantially different in a lot of ways to the earlier castings and the maching process would have to be different. Whether the blind holes are intentional or simply a byproduct of the new machining practices I wouldn't like to hazard a guess.

[Wayne Orwig]

I han't heard about the lower two flang bolt issue. Was making these 2 holes "blind" guzzi's answer to the thru hole oil leakage of earlier blocks? (requiring sealant on the lower two bolts)

They did that starting in about 2003. My 2004 also has blind holes on the bottom.

[lucian]

Thanks Pete, I guess I'll ease off my anxiety med's now. 8)