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Post by scootnewb on Apr 28, 2018 23:47:30 GMT -5
How much damage could having cam off by 1 tooth cause? I was watching a gang of videos about trouble-shooting engine noise. Wrapping, clattering etc etc. One video mentioned a bad crank bearing. How could I check for that without cracking the case?
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Post by GrumpyUnk on May 2, 2018 11:09:35 GMT -5
You should not damnage anything. The only possibility I can think of is a valve colliding with the top of the piston. The crank bearins, main, at either end of the crankshaft, can be checked by trying to move them up, down, and side-to-side. There should be very little play, such that you cannot detect manually.
The connecting rod large end(crankshaft end) could be checked with the cylinder removed. Just grab the piston and try to move it relative to the crankshaft, in the direction of the piston 'stroke'. I.e., pull and push it. You can have sideways movement without having any damage. A little.
If either end of the crank can be moved radially, then there may be clearance problems. I think I would expect to hear rattle and rapping if the bearings were bad, or a 'whine', the noise a bad wheel bearing makes. You may be able to feel roughness in the rotation if the bearings are bad and have galled the race(s). There is almost no clearance between the inner and outer race and the rolling balls. If 'stuff' gets in there, it will be squeezed by the rotating ball, much like a steamroller or asphalt flattening machine. If there's not enough room, the race and/or ball will be damaged, and the damage will 'walk' around the race as stuff falls off. They go quick when they go.
tom
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