farmall cub engine knock

ezed76527 · Jul 25, 2008

just purchased a cub that had not been ran in several years. finally got it started and i have an engine knock. no knock when idle however knocks when you speed up the engine. Sounds like it is coming from the front portion of the engine. I guess it could be #1 cylinder however sounds like it is more forward. Possible timing gears or governor? anyone have similiar problem??? Thought I would request advice before tearing engine down to see if bearing or skirt. thanks in advance

ed

dave guest · Jul 25, 2008

Pull plug wire on suspected cylinder. If it gets quiet, you found it. Might be rod bearing or piston pin. Does it go away when warmed up or get worse. Are you using 30 weight oil. That will silence some little noises.

John M · Jul 26, 2008

I can tell you this, my 49 Cub has had the sae knock for 5 years now. I was told when I bought it the engine had been gone through, and I truct the guy I bought it from, but when I had the engine off for restoration I palstigauged the bearings and they were well within spec. I didnt check anything else. I have though, not ever heard another one that knocked like that.

ezed76527 · Jul 26, 2008

I will pull the plug wires as you suggest. What about the idler gear between the crank and the ignition drive. Is it possible for the engine to knock if the idler gear bushing is worn? What about the governor? It does not sound like a rod or pin knock.

ezed76527 · Jul 26, 2008

problem located. spun bearing in #1 rod. bearing shell remained in place and protected crank. no visible damage and measures only .001 under original.

farmall cub engine knock

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