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Old 03-13-2011, 05:18 PM   #4
Randy
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Join Date: May 2010
Location: Austin
Posts: 696
Default Re: Mystery flathead tapping noise, suggestions?

Quote:
Originally Posted by Bruce Compton, Canada View Post
Randy : Is there a pattern or cycle the " comes and goes" noise , or is it random? I had a similar cycling noise in a "Y" block and it was an out of round wrist pin rotating in the piston. If its a random occuring noise, I'd suspect a sticking valve, or posibly too much end play in the camshaft if the engine was assembled with the wrong set of timing gears ( 8BA type) that thrust the cam to the front of the engine. You may want to run the engine for a few minutes with the belts off as the noise that the generator, fan, belts and pumps are creating will mask the noise you are trying to find, especially at higher RPMs. By doing this you will also eliminate any noise sources from these components. Good luck : Bruce

It does kind of cycle, but it's not a consistent rhythm. I'm kind of suspecting a sticking valve, since flatheads are known for that. I pulled the plug wires off each cylinder and no change, so don't think it's a wristpin although I guess it still could be. I don't think it's incorrect timing gears as this engine has quite a few miles on it and it only just started recently, but seems to be getting worse. Thanks for the advice, I will run it with the belt off and see if that makes a difference. I think I'm going to add some Marvel Mystery Oil to the crankcase. It only occurs at idle and goes away as soon as it's off idle. Thanks!
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