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Sheared flywheel key on a troy built push mower


cghelton's Avatar
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05-12-11, 03:24 PM   #1  
Sheared flywheel key on a troy built push mower

Hi all,
Have been a lurker for some time now. Decided to join...Hopefully someone can help me with my problem.

I was cutting my grass and a shoulder bolt backed out of the front wheel adjustment which has a rod that goes across from wheel to wheel. Well once the bolt backed out, the rod dropped and hit the blade. I didn't think anything of it then. I turned it off and checked it out. Had the local lawn mower store order me a shoulder bolt.

The bolt came in, I put it back together with some loctite. Fired it up and proceeded to start cutting the grass. About halfway into cutting my lawn, it back fired and wouldn't start back up.
And it's really hard to pull.

After reading a few of the threads concerning backfire on here, it looks like it may have sheared the flywheel pin. I took the top part of the mower off and there is NO key way inside of the bolt that you take off to get the flywheel off. Is that normal if it shears it off? If so, can I just replace the key? What about timing? Do I need to put it back in timing after replacing the key?

Hopefully it didn't bend the crank.

I'm pretty sure it has the magneto setup.

The mower is only a few months old.

Thanks a bunch!

Curtis


Last edited by cghelton; 05-12-11 at 03:39 PM.
 
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05-12-11, 04:05 PM   #2  
Took the flywheel off and this is whats left of the key:


Does that looks like it's sheared in half?...Has a pretty good angle to it.

 
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05-12-11, 04:38 PM   #3  
Posted By: cghelton Took the flywheel off and this is whats left of the key:


Does that looks like it's sheared in half?...Has a pretty good angle to it.
Looks sheared to me, you just don't show the other half, by the shape of it I would say it is from a Tecumseh engine. Have a good one. Geo

 
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05-12-11, 05:59 PM   #4  
Geo,
That was all that was left of the key. It was on the very bottom part of the shaft. There was no other piece. Shouldn't it be twice as long as that piece? How hard is it to replace it and get it back in time? How would I know if the crank was bent?

Thanks and sorry for all the questions.


Last edited by cghelton; 05-12-11 at 06:42 PM.
 
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05-12-11, 07:52 PM   #5  
Posted By: cghelton Geo,
That was all that was left of the key. It was on the very bottom part of the shaft. There was no other piece. Shouldn't it be twice as long as that piece? How hard is it to replace it and get it back in time? How would I know if the crank was bent?

Thanks and sorry for all the questions.
The rest of the key is probably still stuck in the flywheel, to replace simply clean everything very well, install the new key in the crank and set the flywheel in place and torque to specifications, make sure it is clean, no lube, grease, etc, when installed the timing will take care of itself as it is controlled by the key, to check the crank, remove the spark plug, install a new/straight blade and turn the engine marking several spots on the undercarriage as the tip of the blade passes, if both ends of the blade pass at the same location the crank is straight, if not it is junk. Have a good one. Geo

 
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05-13-11, 01:31 AM   #6  
Thank you sir!!
I'll report back after I check the crank
and replace the key.

Curtis

 
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05-13-11, 02:55 PM   #7  
OK...Went and picked up a key, have the key in and the flywheel on. Anyone have any idea what the torque should be on the bolt that holds the flywheel onto the shaft??

thanks

 
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05-13-11, 03:50 PM   #8  
OK...After finding another thread about the same thing. I torqued the nut to 65 ft lbs. Took about 7-8 pulls, but it started. Now it starts on the 1st pull everytime!! WOOHOO.

THANKS for your help Geo.

 
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05-13-11, 04:18 PM   #9  
Success is a wonderful sound. Have a good one. Geo

 
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