BENT SHAFT: 3.5 horsepower Briggs & Stratton has a bent shaft.

[Hammermechanicman]

Southwest Ohio. Long drive from WV if that where you are.

 

[MowManWV]

Southwest Ohio. Long drive from WV if that where you are.

That's not a long drive at all. I used to drive 3 hours, one-way, for literally 60 seconds of fun back when I was skydiving every other weekend.

I have driven 19 hours one-way just to ski for two days. (Hopefully will again this coming ski season).

Longest trip was 13,000 miles one-way to see my girlfriend (I didn't drive that one though....car doesn't float).

If you are game to try, I'm game to come. What's your favorite beverage?

 

[4getgto]

I have a crankshaft straighter too. They work very good. Uses a dial indicator and you get them perfect to within a few thousands. Haven't used in years as most all newer engines have very short cranks and rarely bend.
And you do them right in the motor without anything apart other than taking the motor off the deck..

 

[CaptFerd]

Sometimes you got to kiss em good by and just get a new one.

 

[rgrottk]

You have nothing to lose here drain the oil put the mower onit's side and careful hit the shaft high spot with a sludge hammer until you get the shaft as straight as possible. Take your time and then put the blade back on and check your work, don't be afraid of hitting it hard, I did this with one a "friend" gave me it is still running today 2 years later..... You have nothing to lose..... ps From what you describe MAKE sure the shaft is indeed bent I suspect you might just have a broken keyway ..... check this anyway even if the shaft is bent since this will cause the engine to be out of time and pull the cord right out of our hand.

 

[Gord Baker]

Use a Dial Indicator and mark High Side. A piece of pipe over the end of the protected shaft and lean on it.
Check runout often and remember 'spring back'. Replace the seal if you get it 'good enough'.

 

[catman606]

I straightened one using the big hammer method, I could cut grass with it, but it still had enough vibration that I had to tighten the carb bolts every couple weeks. Go down to Lowes and buy you a cheap Bolens 20".

 

[mabel]

I guess that's the end of that! The 20" Murray push mower a mowing client gave me has a bent shaft. I was fearful of that since it had this weird pull of the rope, like it was "catching on something" and the shaft itself (with blade removed) was very wet with oil. The blade itself looked really good though: no damage, only rust.

With blade off though, it's clear the shaft is not sitting in the center of the shaft tunnel.

I now know what to check first when someone gives me a mower!

I'll continue cleaning up the carb and gas tank...........I already have those off anyway.

Anyone have a good shaft laying around they don't want?

If the symptom is the mower seems like it wants to pull the rope out of your hand when you pull it then the flywheel key has sheered.
Remove the flywheel nut and you can usually see if the keyway aligns with the key.
This happens because with a sheered key the mower is "out of time" and depends on how bad the crank is out of alignment with the flywheel the mower will fire the piston backwards as it is not sparking at TDC.

Check If the blade is hitting the deck also.

replace the key and tighten the flywheel back on.

Alot of the time when mowers come into my shop with this issue, you replace the key, then start it and the mower will vibrate when it's running.
This is a bent crankshaft, a badly bent crankshaft and the mower will walk around in circles if left to run on concrete.

If it's not too bad mow with it,. eventually you'll tear it up, or replace the crank or have a shop bend it back.
Most shops won't straighten cranks though, special press/tool to do so,.

 

[MowManWV]

If the symptom is the mower seems like it wants to pull the rope out of your hand when you pull it then the flywheel key has sheered.
Remove the flywheel nut and you can usually see if the keyway aligns with the key.
This happens because with a sheered key the mower is "out of time" and depends on how bad the crank is out of alignment with the flywheel the mower will fire the piston backwards as it is not sparking at TDC.

Check If the blade is hitting the deck also.

replace the key and tighten the flywheel back on.

Alot of the time when mowers come into my shop with this issue, you replace the key, then start it and the mower will vibrate when it's running.
This is a bent crankshaft, a badly bent crankshaft and the mower will walk around in circles if left to run on concrete.

If it's not too bad mow with it,. eventually you'll tear it up, or replace the crank or have a shop bend it back.
Most shops won't straighten cranks though, special press/tool to do so,.

Guys, I like to fix things, which is why I am here and not reading reviews on Lowe's.com .......I enjoy the challenge and opportunity to learn something new. *I'm not hurting for a mower, I have a backup I got running last week and my main mower may be fine after a carb cleaning or rebuild.

So remove the flywheel and check the flywheel key?

Blade didn't appear to hit the deck (blade is off right now) but shaft where blade attaches to it is clearly moved to one side. It has an oblong rotation when the flywheel is spun fast with a drill.

 

[Mattmotors]

I agree with the sledge hammer trick. Worked for me.