Engine main oil seal fitting.

The engine on my rebuild is going to start going back together next week. I see that you can buy a speacial tool to fit the main rear crankshaft oil seal which is rather large and much bigger than any sockets that I possess, and although I can probably fit it without any dramas, would like to ask the following. Is the special tool necessary (which I doubt). Is it best to fit this oil seal before putting the housing/main bearing in place onto the crankcase and over the crankshaft, or afterwards? Any other good advice from experience welcome.

I would gently tap it in place by goind slowly around it can always use the old seal as a cushion .
I would also put it in after the crank at least everything is central then and you cant chop it when placing the crank into the bearings

+1The crank seems to aid fitting by centralising the seal. Have used a small plastic mallet to work around the seal in the past. Finished with some platic dowel used as a soft drift to get the seal fully home.All the best,Steve

Main oil seals, if this is the big one behind the clutch, can be a git, took me 3 goes to get a seal, and that inot the record even Guzzi dealers have been known to have to do it 4 times.

So here is what I found out (On the THIRD ATTEMPT ) Get some silicone sealant for engines, really make sure the casing is ultra clean and smear that is SMEAR the silicone around the casing very very thin smear then pop the bearing inI used the cusion and rubber mallet but if i remember i did have something that diameter.

I got the tip from a very very good Guzzi Mechanic and it worked real well so good that all seals now go in with this method something to do with the metallurgy of the casings and all that clever stuff All I know is it worked

I thought that putting the seal in first was going to be the preferred method, and am slightly suprised that it’s 3-0 to putting the seal in afterwards, but then that is why I asked the question. I will defer to the experience of others that have alredy done this task. Thank you for your help.

I found that if you fit it first then slide the crank inplace you can damage the inner sealing face if thecrank goes in at a slight angle
o and by the way it goes in with the spring facing the enginenot the cluch (i haveseen one backwards they leak like mad then the oil has to go to the spring or cupped side so that the pressure squeeses it onto the shaft