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bowlake

vibration

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bowlake
I just had a onan 20hp rebuilt for my a/c 720. I have never had or herd this motor before. Started up after a complete rebuild from a machine shop. Tractor vibrates along frame up to the steering wheel. It increases as you increase the RPM's. Is this common with the onan engines. If you push clutch in the vibration is still there. Am I over reacting.

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D-17_Dave
A serious vibration has the potential to be catasrofic on whatever is causeing the imbalance. Did you replace the engine yourself? The problem may be the rear PTO shaft out of alignment causeing a seviere vibration up through the steering column. Other than that, a bad flywheel or something else to do with the engine. My CCKB is very smooth at most RPM's. Also, did you test run the engine out of the tractor befor instlation? This would tell you if it's in the engine or something hooked up on the tractor end.

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cranemech
Morning, I would isolate the engine from the tractors moving parts undo driveshafts ,belts, front pump, etc and then run the engine. This will tell you if it is in the engine or something being rotated. I picked up a vibration on my onan and found that one of the bolts on the driveshaft had loosened up and started wearing into the coupling disk. Later, Chad

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D-17_Dave
If everything is dis. then I would have to consider the flywheel, maybe loose or bent, broke or a bad crank, worse case. But you say a vibration. It's very diff. to narrow something like this down without putting a hand on it. One thing I have learned is not to trust someone elses work. Meaning if someone else has done a "little" something to it somewhere and says it's OK, and that little something might have something to do with your problem, don't take for granted that it's OK, Cheeck it again for yourself.

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bowlake
I agree with you Dave, the man that rebuilt the motor has not come out to look at it yet. But did say the same. I didn't like the part with the poss. broken crank. I have alot of money in this motor. When you have you hand on your steering wheel do you have any vibration? My fingers will get num at 1/4 throtle. Checked flywheel and looks ok. I will have to waite till the person who did the work looks at it. Im off to Flordia for a vacation. I will let you know how I make out. Thanks,

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