1951 14hp evinrude woodruff key/flywheel probs

[nutts]

Have an issue with this motor shearing the key that pins the flywheel, cam ring and crankshft. The motor is smooth as can be and then out of the blue with no warning the key will shear and obviously get out of time and stop. But why the key issue? There is 'some' wear on the flywheel where the keyway is, but isnt extreem. Is that minimal wear enough to cause that much backlash to bust the key?

Thanks for the help fellas.

 

[F_R]

Re: 1951 14hp evinrude woodruff key/flywheel probs

Improper installation of the flywheel will cause the key to shear. Every time it shears, it causes some damage to the shaft and flywheel. There comes a time when it is so damaged it won't hold at all.

All you can do is make sure it is properly installed. If it then continues to shear, well--so sad.

"proper installation" means the shaft and flywheel tapers must be clean, smooth, and dry. The keyways must not be battered or loose. Then, you MUST use a torque wrench to tighten the nut to 40-45 foot pounds. If this had been done way back when it all started, there wouldn't be a problem now.

 

[nutts]

Re: 1951 14hp evinrude woodruff key/flywheel probs

so a new flywheel basically or possibly a slightly longer key to get a tighter fit.

 

[CATransplant]

Re: 1951 14hp evinrude woodruff key/flywheel probs

so a new flywheel basically or possibly a slightly longer key to get a tighter fit.

Nope. The key does little to nothing to keep the flywheel from slipping. It's only there to make sure the flywheel is in the correct position. The tapered crankshaft and matching taper in the flywheel are what keep the flywheel from slipping. Only if they are smooth and mated will you not shear flywheels. The proper torque on the flywheel nut puts enough pressure on that tapered connection to hold the flywheel in place. The key is just there to align the two for proper ignition timing.

 

[samo_ott]

Re: 1951 14hp evinrude woodruff key/flywheel probs

Have you been torquing down the crankshaft nut?

I have the same engine but have never tried to get it running yet.

 

[nutts]

Re: 1951 14hp evinrude woodruff key/flywheel probs

Have you been torquing down the crankshaft nut?

I have the same engine but have never tried to get it running yet.

Yep, torqued everytime. Ive gone through the process 4 times of replacing the key, looking at things and making sure things are tight. BUT I have noticed that the flywheel nut has loosened up when it breaks the key, almost to finger tight.

 

[wilde1j]

Re: 1951 14hp evinrude woodruff key/flywheel probs

... and you used a proper key, not a hardware store piece?

You may be out of chances here, but it may be possible to lap the crank taper to the flywheel, but I would suspect there may be too much metal gone already. I would try the mating with Prussian blue first, before anything else. If the mating is good, I would try one more time using a new nut. The nut typically loosens when the mating isn't good.

 

[Cofe]

Re: 1951 14hp evinrude woodruff key/flywheel probs

Was reading your post, and was wondering if you are putting woodruff key in properly. The rounded part goes into the crankshaft. Also see picture.

 

[1946Zephyr]

Re: 1951 14hp evinrude woodruff key/flywheel probs

One thing you can do, is oce you do get it running again, see if there is a wobble to the flywheel as it's spinning. An improper flywheel key will prevent the flywheel from seating all the way on the taper. This kind of explains why your flywheel nut is loose, after it shears off the key. I think the best thing to do is, order the proper key from Sea-Way marine, up in Seattle. If they don't have it, try Engine Blade and Prop. These two places I have found to have a pretty good supply of parts for these older engines.

 

[F_R]

Re: 1951 14hp evinrude woodruff key/flywheel probs

Like I said.....

 

[samo_ott]

Re: 1951 14hp evinrude woodruff key/flywheel probs

Maybe try some loctite on the flywheel nut?

 

[wilde1j]

Re: 1951 14hp evinrude woodruff key/flywheel probs

... yeh, or maybe weld the flywheel to the crank after you install the magic, permanent points. Guaranteed to not come loose, ever!

 

[nutts]

Re: 1951 14hp evinrude woodruff key/flywheel probs

... yeh, or maybe weld the flywheel to the crank after you install the magic, permanent points. Guaranteed to not come loose, ever!

great idea. thats what ill do.