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Wayne
07-06-2003 18:55:52
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Re: Gaskets? in reply to Sean W, 07-06-2003 00:09:28
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I've built everything from inline 6 cyl Murphy diesels, to 8V-92 Detroits, to Briggs and Stratton lawn mower engines, and I can tell you from experience that one of the most important things is to make sure that the gasket surfaces are clean. I always use the Scotch Rol-Lok discs for this. Just make sure you use the right disc for the type of metal to insure you just clean the surface and don't gouge it. As far as a sealer to put on the gasket, the best thing I've found, especially on oil pans and things like that is a THIN film of Ultra Blue or Ultra Copper. ANYTHING but plain old silicone, since it tends to squeeze out into places it shouldn't be and can block ports, etc, causing problems later. On larger gaskets that need something to hold them in place, then use something like Copper Coat as some have mentioned. Suprisingly enough on some of the "foreign" engines like the Yanmars, they don't even use gaskets, instead they use what is best described as a gasket compound that is almost like Loctite. You simply smear it on and assembly the part, and it seals from there. For head gaskets, it's not normally recomended to use anything unless the manual specifically calls for a sealer, and then it's usually limited to use around oil drain back ports, water ports, etc. Lastly as has already been mentioned, the correct torque is also important. Usually the factory torque specs take into account the diameter/size of the fastener as well as the length (affects how much it can stretch), as well as the grade, and also the material it is threaded into. If you don't have the factory specs, you can often use a standard chart as a guide, but even that isn't always reliable. Some mfgs don't actually give torque specs for things like head bolts, but rather rely on different methods such as streching the bolt,ie- giving a spec such as tightening to a specific torque and then going so many degrees tighter to strech it. It's things like this that can often make building an engine a challange. Still with time and experience it isn't all that hard. The main thing is to realize that somewhere out there somebody built it, and if your willing to ask questions, you can do just as good a job as the factory.
Good luck on your future projects. Wayne
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