removing tight/stuck blade bolt

[jbclem]

I have an old Murray 21" power propelled convertible mower, model 21772x7A. It's been sitting unused for at least 20 years. I'm trying to remove the blade but can't get the bolt to budge, and it's starting to round off. Could someone tell me the bolt head size so I can make sure I'm using the correct socket/wrench. And the direction it should be turned to loosen it.

Also, any tricks to removing a stuck/frozen bolt like this one?

 

[impalaman]

I have an old Murray 21" power propelled convertible mower, model 21772x7A. It's been sitting unused for at least 20 years. I'm trying to remove the blade but can't get the bolt to budge, and it's starting to round off. Could someone tell me the bolt head size so I can make sure I'm using the correct socket/wrench. And the direction it should be turned to loosen it.

Also, any tricks to removing a stuck/frozen bolt like this one?

Most blade bolts take a 5/8" socket. Use a 6 point socket instead of a 12 point so it will give you a better grip on the bolt. Turn counter-clockwise to loosen the bolt. If you have an impact wrench, I'd use it with the 6 point 5/8" on it. Otherwise, use a 1/2" drive ratchet or breaker bar. If you round the bolt off too far, have someone tack weld another bolt on to it about an inch long or so and use that to turn it out. Then just replace the bad bolt.

 

[ILENGINE]

Most of the newer mower bolts are 5/8" but the older ones like you have could be either 1/2 or 9/16"

 

[Bertrrr]

Always use a 6 point socket for these and when re installing add some grease or never seize to the threads That bolt is pretty much junk now so if you need to use a pipe wrench or something to remove not goin to hurt anything, warm up with a torch until cherry red and it will work loose for you

 

[StarTech]

The screw used was a 3/8-24 x 1-1/2 right hand threads so it hex size would be 9/16. Replacement should be a grade 8.

 

[Roy405]

Most blade bolts take a 5/8" socket. Use a 6 point socket instead of a 12 point so it will give you a better grip on the bolt. Turn counter-clockwise to loosen the bolt. If you have an impact wrench, I'd use it with the 6 point 5/8" on it. Otherwise, use a 1/2" drive ratchet or breaker bar. If you round the bolt off too far, have someone tack weld another bolt on to it about an inch long or so and use that to turn it out. Then just replace the bad bolt.

Or use your largest pipe wrench on that rounded nut

 

[jbclem]

Looking from underneath the mower, when you pull the starting cord the blade turns counter-clockwise...(or clockwise when looking from above.) Does this jive with loosening the bolt by turning it counter-clockwise?

 

[sgkent]

every hear of Liquid Wrench, PB Blaster etc.? Try it. Might help.

 

[jbclem]

The bolt head is so tight that I didn't think a penetrating oil would get past the head...but I should order some and try it. However, I need to be sure of the direction that I would turn the bolt to loosen it. I've seen conflicting advice somewhere else.

 

[ILENGINE]

The bolt comes loose the same direction that the blade spins to cut the grass.