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520-H Onan PTO Whining/Whistling Noise

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I have a 520-H with the P220 Onan motor. For a while it's been whining/whistling when i engage the pto, but as soon as the pto's fully engaged, the noise goes away. This weekend however, the nose persisted for about 10 minutes while i was finishing mowing. It did the whining in the winter with my 2-stage blower hooked up (again, just while it was being engaged, but once fully engaged it was ok). So this weekend the noise became 'permanent' - and i'm afraid it's a bearing that's gonna require a rebuild. It also gets louder with engine speed. Seems the more load is on the pto, the louder and more pronounced it gets.

Is there something I can look at or try to get this to go away without pulling the crank shaft and bearing out? I really dont want to replace the motor.

Thanks in advance!


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I highly doubt it is the main bearing in the engine. When you push the pto lever forward to engage the pto. The pto cone which the belt rides on has 2 bearings in it. There is a needle bearing, and a regular ball bearing. I recently picked up a 418A and at first I thought it was the deck, so I changed the decks and it still persisted. I turned off the tractor and touched the pto cone by the engine it was warm, and I touched it by the stud which connects to the hoop by a pin and burnt my fingers. My recommendation is to take off the pto cone and see if the ball bearing on the end which is held in my snap clips is shot by spinning it with your fingers. You will know its bad if its loose, makes noise when turning it, or is hard to turn. If it is okay it should have extremely little to no play, and also be smooth and quiet.


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I pulled the pto cone off today and greased the needle bearings, even though they spun just fine. The other bearing where the pto hook pushed on the pto when its engaged turned but grinded a bit when i spun it. I sprayed every sort of grease and lubricant i could find around it and let it sit for a while. When i put it back, the pto still whined when i engaged it but it wasn't consistently whining while it was running. So i'm pretty confident that if i just got a new cone it would be fine.

Thanks! So glad it's not engine - related :)

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No problem, it is easier to just replace the outer bearing it comes out by removing the big snap ring, but I would remove the little one first that holds in the stub shaft.

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Can i get the bearing out by myself without a press? I have a bottle jack and could probably rig something up to make a press. Would the bearing come out just by hitting it enough times strategically with a hammer?

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So i replaced the ball bearing, and i still have some whining coming out of the pto. I'm wondering if now its the clutch plate behind the bell housing? Also, i picked up a 2nd 520-H and it's got the same issue, so i can't swap parts... Should i look at the clutch plate next? Maybe replace it? The needle bearings look / feel fine to me. Should i also just replace that to do it?


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