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Lawn Boy lawn mower blade won't come off

#1

M

mowerman522

Ok so I don't know what happened, but I was tuning up my dads 4.5hp silver series lawnboy and I put a c clamp on the side of the deck to stop the blade which worked great, but when I loosened the nut the blade stays still and the crank moves with the nut. What happened? It almost seems like the flywheel came loose instead of the blade nut. I don't see how that's possible. It has a 4.5hp Tecumseh 4 stroke that's probably around the mid 90s. Also it's got some kind of fancy mulching blade on it.


#2

J

jp1961

Hmmmm,,,not real familiar with 4 strokes, but it looks like your options are put a pair of vice grips on the crankshaft or buy a piston stop tool which replaces the sparkplug and locks the crank.

Jeff


#3

B

bertsmobile1

Blade has a round hole in it and is held tight by the clamping force of the nut.
Once you loosen the nut 1/2 turn it no longer holds the blade so the shaft can turn freely.
As already stated,
Remove spark plug, feed as much thick nylon rope down the plug hole as you can, leaving enough out of the end so you can pull it out.
Rotate the nut in the direction of undoing slowly till the piston squashes tight against the rope.
You can now undo the nut.
Clean up the threads they are most likely rusty & bent.


#4

M

mowerman522

bertsmobile1 said:
Blade has a round hole in it and is held tight by the clamping force of the nut.
Once you loosen the nut 1/2 turn it no longer holds the blade so the shaft can turn freely.
As already stated,
Remove spark plug, feed as much thick nylon rope down the plug hole as you can, leaving enough out of the end so you can pull it out.
Rotate the nut in the direction of undoing slowly till the piston squashes tight against the rope.
You can now undo the nut.
Clean up the threads they are most likely rusty & bent.
Click to expand...

Oh ok. That explains why the nut is so big. I was expecting it to be like a briggs where it mounts onto an adaptor that's connected on the crank with a key.


#5

M

mowerman522

Well I got it off. Everything was fine. Honestly I thought I stripped out the blade adaptor or something like that so I was freaking out for no reason. I just used some vise grips to hold it.


#6

P

Phototone

I always struggled getting the nut off until I discovered the easy way. I just use an air impact wrench. Gets it right off, and then getting it tight enough when replacing it is a piece of cake with the wrench.


#7

B

bertsmobile1

mowerman522 said:
Well I got it off. Everything was fine. Honestly I thought I stripped out the blade adaptor or something like that so I was freaking out for no reason. I just used some vise grips to hold it.
Click to expand...
Try not to use things like vice grips or stilsons because they leave little gouges in the shaft which become initation points for cracks shoul the shaft get overloaded which is why you use piston stops ( rope )


#8

J

jp1961

The other down side to using vice-grips is the marks it would leave would cause problems if you ever had to replace the bottom crankcase seal, the rope idea is a good one.

Jeff


#9

K

Kremeneon

Phototone said:
I always struggled getting the nut off until I discovered the easy way. I just use an air impact wrench. Gets it right off, and then getting it tight enough when replacing it is a piece of cake with the wrench.
Click to expand...

This. the impacts use the intertia of the shaft and flywheel against itself to turn the nut off without having to clamp or hold anything in place. And it takes about 2 seconds.


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