Stripped Threads on Crank

[mav6759]

I have a 2001 Mercury 90hp. I stripped the threads on the crank that holds tbe flywheel down..The nut wss totally stripped.. I know I'm going to need that nut to hold down the flywheel..I was wondering is there another way that I can create new threads on the crank without a tap & dye..

Thanks Mavhave any help will be appreciative

 

[racerone]

Never seen that before.----Did this happen taking the nut off or putting it on ?----Why were you taking the flywheel off ?

 

[tommarvin]

You said you stripped the threads on the crankshaft, and in the same breadth you said the threads on the the nut were totally stripped?
Are you sure you need to tap new threads on the crank, or do you need a new nut.
If you need new threads on the crank, you can get a cheap tap and die kit at harbor freight tools.
Just wondering, how did you hold the fly wheel tight enough to strip the threads on the crank?

 

[jimmbo]

Stripped external threads on a crank are not good. If it was me, a new crank is the only repair. Any new threads would end up being on a smaller shaft, and smaller nut. Would the new size be strong enough to accept the torque value? An additional washer and lock washer would be needed too.

I have seen butchered cranks after someone figured an impact wrench could be used to remove and install the nut.

 

[Scott Danforth]

to help future readers, please explain how you damaged the threads on both the nut and the crank.

pictures will help

while it is possible to remove the crank, weld up the stub, re-machine it and re-install it, a new crank or a used power head would be cheaper.

 

[mav6759]

Well the motor was stuck and it would not move.. so I put a 600 pound and a 1200 pound impact gun on the crank... to be honest, I have not checked the crank, I assumed the threads on the crank were done because the nut was.... but I got the motor unlocked and running...

 

[Grub54891]

Well the motor was stuck and it would not move.. so I put a 600 pound and a 1200 pound impact gun on the crank... to be honest, I have not checked the crank, I assumed the threads on the crank were done because the nut was.... but I got the motor unlocked and running...

So it's running, you didn't get the nut off, but it's stripped. I would not run it like that, the fly wheel will come loose, and possibly throw itself through the cowling, hitting you or someone else, resulting in severe injury.