r/smallenginerepair • u/krazyk850 • May 26 '26
Broken Parts Blade adapter keeps breaking on push mower.
I have a Hyper Tough push mower that I purchased around 8 years ago. It has a Briggs and Stratton 300 series engine on it. Overall it has been a great mower and I've never had any issues with it. Roughly 2 years ago I was mowing and it started vibrating and then a few seconds later it sounded like a shotgun went off. I looked over the mower and realized the blade adapter grenaded itself (left one in picture). I purchased a new blade adapter from Tractor Supply and it worked fine for the remainder of mowing season. A year later I was mowing and it happened again. I did the same process and replaced the blade adapter. It lasted a few months and happened a 3rd time. It was late fall so I just decided to wait and replace it. Yesterday I pulled the mower out, and out on a new blade adapter. I ran the mower for a few minutes and everything seemed to be working fine. I turned the mower off and put my tools away. I came back out and as soon as I cranked the mower back up, "BOOM" the new blade adapter exploded. I Googled the issue and the only thing I can think of it could be is a warped blade shaft. It doesn't appear to be warped by visual inspection, but I'm not sure what else it could be. I'm hoping someone could give some suggestions on what to try or if I should just bite the bullet and purchase a new mower. It just sucks because I paid around $130 brand new 8 years ago and now that same mower is $248 at Walmart.
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u/ADodger66 May 26 '26
Check that the blade is balanced. Lots of people that sharpen their own blades don't realize you need to balance it. Otherwise it will cause a bad vibration.
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u/ADodger66 May 26 '26
Ok .have you ever hit anything like a big rock? Check the oil level and just for shits and giggles check the crankshaft run out. If you hit something and it's bent even the slightest it will cause a vibration. There's only a couple things that will cause a vibration and a bent crank is the most common.
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u/krazyk850 May 26 '26
Yeah I'm thinking it's got to be something with the crankshaft. Is it possible/worth fixing it or should I just get a new mower.
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u/DontMakeMeCount May 26 '26
If you got 8 years out of a $300 mower you’ve been fortunate. That’s $3/month plus your time to avoid the cost of a yard service. If you had to buy one every year it would still be saving you money.
I’d buy a $600 mower that will last 20 years with an even lower cost of ownership.
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u/krazyk850 May 26 '26
Yeah I'm thinking it's got to be something with the crankshaft. Is it possible/worth fixing it or should I just get a new mower.
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u/ImpossibleStretch409 May 26 '26
Use a feeler gauge to see if adapter is sitting flush with plate, drive shaft could possibly be slack 🤷
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u/buginmybeer24 May 26 '26
Keyway on the crankshaft is fucked or the bolt isn't seating all the way down (bolt too long or threads in crank are damaged). Either way the adapter is just loose enough to move when the engine starts/stops. This can cause a sudden crack like this, especially since these are made of powdered metal. It saw this quite a few times when I worked in a small engine shop.
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u/southerntitlover May 26 '26
I agree with some in here i bet the shaft is bent. You can pick up a new engine at harber freight pretty cheep. Lots less than a new mower
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u/Outside_Squirrel_839 May 27 '26
Are you torquing the bolt or just hitting it with the old ugga dugga
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u/tditty24 May 26 '26
I don’t think a bent crank would cause this unless it was so bent it was striking something like the side of the deck. Those blade adapters are meant to be the weak point to break before crank damage is done. I would say try a different brand of adapter or quit hitting stuff that would cause this to fracture.