Mower Making Unusual Sound

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We had some insane rain here over the past few days, so it has been a full week since I was able to mow my lawn.  Much of the lawn was actually underwater for a day.  I normally mow every 3-4 days, so I raised the cutting height from 3 to 4 to make mowing easier on the lawnmower and the grass (never have cut this high before). 

You can see that my usually fairway-length (okay, first cut) lawn had a really rough week:




The lawnmower seemed to be handling it like a champ though, despite the thick grass still being quite wet even after waiting three full days to mow after the rain stopped.  Cleanly cutting with no overloading or stalling out.  But after a few passes it started making a rumbling sound and vibrating pretty heavily.  I stopped and completely cleared and cleaned the deck, put a brand new blade on, and resumed mowing without any more issues.

A few passes further, it started doing it again.  I cleared the deck and checked the blade, which still looks brand new.  When I start it up it sounds perfectly normal until I start mowing again, then the rumble and vibration come back immediately.  Here is a video after starting back with the new blade and clean deck, and the noise and vibration start back around 30 seconds in.



Is there any sort of maintenance that I can do or anything that I can check myself, or do I need to stop mowing and leave my lawn half cut and contact Ego for repair?  I really don't want to leave the lawn half mowed, but I don't want to kill my mower either.
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David Cline

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Posted 4 years ago

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Blue Angel, Champion

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I can't watch the video right now, but if it were me I would at least try to finish cutting the lawn. If the blade is good and there's no buildup under the deck I'm not sure what else you can do?
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Ken, Champion

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Assuming the new blade is balanced, I don't know what else you can do. I would be inclined to keep mowing. Whether you have it looked at now or wait until a failure, either way it would have to go into the shop. Might as well get your lawn done before giving it up.
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Joe

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The EGO mower manual mentions a few things that can cause excessive vibrations:

If the equipment should start to vibrate abnormally, stop the motor and check immediately for the cause. Vibration is generally a warning of trouble.

WARNING: If you strike a foreign object, stop the motor, and remove the safety key. Thoroughly inspect the mower for any damage, and repair the damage before restarting and operating the mower. Excessive vibration of the mower during operating is an indication of damage. The unit should be promptly inspected and repaired.

WARNING: An unbalanced blade will cause excessive vibration when rotating at high speeds. It may cause damage to mower and could break causing personal injury.

5. To check the blade balance: clamp a nail or a screw driver with a round shank in the horizontal position. Position the blade so that the nail or round shank of the screwdriver supports the blade through its center hole. Balance the blade horizontally. If either end of the blade rotates downward, remove some metal from the heavy or lower end until the blade is balanced. It is balanced when neither end drops (Fig. 26).

Excessive vibration
  • Cutting blade is loose. - Tighten the blade bolt.
  • Cutting blade is unbalanced. - Balance the blade following the instructions.
  • Bent cutting blade. - Replace the blade.
  • Bent motor shaft. - Contact the service center.
(Edited)
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Jacob

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I think i have had this happen. What happened to me, was grass gets balled up under the deck and actually rolls around the bottom of the deck like a ball. You would also have a lot of grass on the bottom of the deck. If you dont have a caked with grass deck, its probably not the case.
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SCDC, Champion

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This happens to me often with damp grass, even a few days after a rain.  The grass clippings are very moist.
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Steve Valdes

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When this happens when mowing longer wet grass it is best to cut higher and bag the clippings so they don't build up as easily on the underside. I find mulching when the grass is wet is counterproductive and creates more build up and the need for cleaning of the deck.
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icrooks

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Yeah, I get this all the time. The grass build up really quickly when it's long or wet and I have to clean it all out every few passes.

One way to confirm is to clean it out and run it when it's parked on the driveway to see if the vibrations come back.

I'm getting the impression from reading many of the issues and from personal experience, that the mower isn't really built as robustly as your typical gas mower. The deck is plastic and the blade is lighter and I'm not sure how the torque stacks up against a gas-powered job. These factors all contribute to the performance issues many of us have. 
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Blue Angel, Champion

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I don't know about that. Torque is not an issue as long as the blade is kept spinning at the intended speed. If it's bogging down in wet grass torque would be an issue.

The design of the cutting system (blade, deck shape) seems to be the issue, but it would also seem that it's not an issue in the vast majority of situations. In a case like this, where the grass is extremely long and very wet, it may be pushing the limits of the system.

As someone else suggested, doing a higher than normal cut while bagging might be the solution, followed up by a normal height cut a day or two later just to get things caught up.
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Jennifer VandeWater, Community Manager

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Official Response
Hi David, we checked with our engineers and we suspect it's a build up of grass on the deck, just as Jacob described.
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David Cline

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Thanks for the feedback everyone! I did finish cutting my lawn and it all turned out fine.

Usually when the grass is wet or too long I get overload shutoffs, not this balling of grass clippings. Since I wasn't getting any overload warnings and the grass was cutting fine, I thought it must be a blade balance issue. So I was confused when a new blade and (starting with) a clean deck didn't solve the problem.

The vibration actually did feel exactly like a lead weight swinging around the deck, but it sounded more like the blade was scraping the deck somewhere. Hard to believe after two full dry sunny days that the clippings would still be the wettest I've ever seen, but it seems that was the source of this strange noise. Hope you never look out a window and see your lawn underwater!

Hopefully the answer to my question will help someone else when they hear this unusual noise for the first time! And just to be clear, if the grass balling up around the blade doesn't cause an overload, continuing to cut won't risk damaging the mower, correct?
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Jennifer VandeWater, Community Manager

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We think that would be correct David.  Your mower might have been really close to actually overloading but just below the threshold in your case.  If the mower does sense an actual full overload, as you've seen, it will shut itself down to protect itself.
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Jacob

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When this happens to me, its when i am.mowing on height setting 3, when i change to 4 the problem goes away.
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Barry Harber

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My problem exactly.   Mine is when I am mowing a very thick section of grass.  The mower should speed up to compensate, but does not.   Instead, it vibrates and almost dies out.   I press down on the handle and raise the front wheels of the mower off the lawn and it then "catches its breath" and goes back to normal until I hit the thick area again.   Why does it no longer speed up under heavier loading??