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did anyone have a problem leaking oil on seal behind rotorino (pickup)
I have already changed three oil seals and always the same

I did change a couple of seals on one engine, till I realised the oil was coming from one of the screw holes inside the pick up cover. I think it was the 4mm screw holding the pick up stator. I used a little thread tape (PTFE) to cure it.

Reviewed everything again, oil leaks on the seal, the threads are dry. Absolutely everything on the engine is new and that's the only thing wrong.
oil seal is original 13 * 26 * 5 I'm thinking of try to put 12 * 26 * 5
On the camshaft there is no damage everything is perfect so I really have no idea anymore

It is possible that when you fit a new seal the lip is being damaged by the sharpeness of the camshaft shoulder where it reduces down to the male thread. If you look in the blue book there is a list of sleeves that are disirable for fitting to various shafts when assembling the engine or renewing seals. I made up a complete set but no idea where you can get some from.
However, the make do is to wrap electrical tape round the camshaft so that the seal expands smoothly to fit the camshaft diameter, covering the sharp edge, lubricate before fitting the seal. Once fitted then you can carefully peel the insulating tape from the camshaft. If you use the slightly smaller seal then there is the chance that a groove will be formed in the shaft over some time, I have found on various engine where this has happened even with standard seals.

I know that and I have made a complete preparation and tool for mounting the oil seal. it's not my first engine to build ... that's why I don't understand why it's leaking

I had a persistent leak of the crankshaft seal. I bought a viton seal and leak now gone. No idea why, but I was desparate!

That's my first thought oil Seal to be damaged by high temperature but I bought an oil seal that is declared up to 200 degrees

Maybe you were just unlucky and the seal was faulty. It's not a common leak point on a Morini so I would replace the seal (with the correct size again-as mentioned earlier) and suck it and see! It's a pretty cheap option too!

Check the camshaft again for a slight groove. Otherwise I am out of ideas. Good luck.

No groove, I'm crazy

I finally solved the leak on the oil seal. The problem was in the brass pix entering the bearing everything was eccentric and this caused the oil seal to strain and oil to leak.

Morini047 wrote: ↑09 Jun 2022 18:56 I finally solved the leak on the oil seal. The problem was in the brass pix entering the bearing everything was eccentric and this caused the oil seal to strain and oil to leak.

Congratulations, and thank you for explaining how you fixed the issue.