Re: Parting Line Seal
The crankcase spaghetti seal is not really necessary. I believe that Merc did away with it in later engines and OMC never used it. You can leave it in the groove or remove it, but it is best to remove it and clean the crankcase mating surfaces. It comes out easily and will retain its shape when you put it back.
I have used various things with good results: I have used small gray screen splining to replace the red seal when it did break. I have used black and white silicone to seal it in. I have used red locktite anaerobic sealer like OMC uses. In fact, I have simply filled the crankcase groove with silicone sealer.
The simple fact is that the two surfaces of the crankcase are machined so well that they will usually seal well when the engine is run. You can use almost anything that is heat and oil resistant. Just be certain to put a little dollop at the point where the seal meets the upper and lower crankshaft bearings.
Remember: There is only about 2-6 psi vacuum and pressure inside the crankcase while running--not a lot!
