unable to remove bolt to replace blade on lawn mower

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i have the 20 inches mower, about 2 years old. blade needs to be replaced. got new blade but i can't remove the bolt to get the old blade out. tried wd40 and 2 adults tried to turn the wrench, not working. what do i need to do? mower is garbage now?
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leo

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Posted 2 years ago

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Jacob

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Impact driver. You need vibration. But dont go to town on it. Put a screwdriver in the hole in the bottom of the deck to stop the blade from spinning.

Dont use an impact wrench. Too much power. It is normal thread, it is NOT left hand thread.

You havent sharpened your blade ever? Wow....
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Egocentric

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Off the top of my head, I would say take a look in your owner's manual and make sure the bolt has right hand threads.  Some applications use left hand treaded bolts (like the mid 60 Chrysler Product left side wheel studs).  I checked my manual on a new 20 in and it has right hand threads.  But maybe the older modes incorporated a left handed bolt.  Assuming that is not your problem, you might try an electric operated impact gun.  I don't know if you can rent one or not (I own an old Craftsmen model and it has saved my butt more than once).  You want to use a good quality 6 point impact socket.  Don't use a 12 point socket from a socket set.  A six point socket looks like a hex.  An impact socket is black and has heavy thick high strength walls. 
Soak it down good with penetrating oil and try the impact gun.   CAUTION!  Make sure you have the blade blocked like they show in the manual.  The impact gun will spin it like a lawn mower.  Also make sure you have the impact gun going in the right direction or you will get a 180 degree turn in the blade.   Keep the penetrating oil off the plastic housing.   I am told the PB Blaster works much better than WD40.  I don't know, it didn't seem to work that much better to me.  Again keep it off the housing.  

The other thing?  You got a 5 year warranty.  Let them worry about it.   No lawn mower though for a while.  I would try the impact gun, but then again, I own a impact gun. 
(Edited)
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Egocentric

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I will defer to Jacob regarding the power on the impact gun, verses the driver.  But you can just bump it on and off rather than laying into it. 
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Sid Parish

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It can't hurt to try and use an impact wrench if it's stuck
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(a)Typical Engineer

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I have the very first 20" mower without the fan between the bottom and the blade, it is RIGHT HAND thread.

You can absolutely use an impact gun to remove; however, be cautious when re-installing.  For that you should use a torque wrench (specification in the manual).  I use a Milwaukee M18 Fuel 3/8" Impact Driver with 6-point Impact Sockets (as Egocentric said, good recommendation); I use it for re-install too, but I've worked on mechanical bolted things for decades, so my hands are "calibrated" to apply the right torque. =)

The screw driver setup is required if you are not using an impact, e.g. just hand wrenches or sockets/ratchets.  But not really required when using impact tools.

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TK

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That's what happens when you don't take it off to sharpen it for that long..
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leo

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i double checked the original manual it said counterclockwise to loose it. since i don't mow that often (maybe once or twice or month, 4 to 5 months a year for the past 2 years), the blade seemed to sharp until it hit some rock this time. I used torque wrench and i am unable to remove the bolt despite spraying with wd40. I will get a pb blaster tomorrow and borrow a impact driver or wrench to see if it helps.
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Jacob

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Or put a wrench on it, and tap the wrench with a hammer. It will simulate an impact gun. Impacts can sieze threads if not use properly, or if there is enough corrosion in there to cause the thread to peel from the bolt. If that happens, nothing you can do.. maybe drill it out and retap it.. but thats a bad situation. Make sure if you do use an impact gun or driver, dont lay into it too long. It generates alot of heat, heat can be very bad and peel the threads..

Tap on a wrench with a hammer. It will come off.
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leo

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Thx, Will try the hammer/wrench route 1st. For the impact tool, my friend has a cordless impact wrench i can borrow if needed (he said it is 18v 1/2 in). Will that tool do the trick if the hammer/wrench is not working out?
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Jacob

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Yeah. That will be more than enough. Be careful. 1/2 impact electric or pneumatic will be powerful.
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(a)Typical Engineer

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Yes, that should work.
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Egocentric

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Yes the wrench you described should work.  As Jacob indicated don't lay into it too long.  Also shock it a bit with the wrench and apply more PB Blaster and let it sit a bit then come back and try again.  And be sure to keep the PB Blaster off the plastic.  

The other thing I would caution you on, know when to quit.  You should still have a warranty on the mower.  Best not to end up voiding the warranty with rounding of the bolt or some such thing.  Again 6 point impact socket is a must.   Using a 12 point light wall socket will most likely round off the bolt head or break the socket or both.  
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leo

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thx for all the ideas. I got a metal pipe to extend the torque wrench. and i was able to loose the bolt.
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Egocentric

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Excellent!  I am glad you got it out ok.  
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Blue Angel, Champion

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Glad to hear it, leo. Remember not to put it on that tight when reinstalling the blade! :-)
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leo

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i hear you! thx all
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Jacob

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Maybe anti seize
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(a)Typical Engineer

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Or just standard grease, anything would be better than nothing.

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