crankshaft key broken?

[hondarider188]

the key on my johnson seahorse 18 is broken and wore down the wheel still catches it but the question I have is if it is just a key that i can replace or is it a solid piece of the entire driveshaft and not worth fixing.

 

[jbjennings]

Re: crankshaft key broken?

The key is very cheap to replace but must be an OMC key, not from the hardware store. The flywheel must be installed to 45 foot-pounds of torque or it will break again. It's called a woodruff key. Crank taper should be free of rust and oil-----DRY.
Good luck,
JBJ

 

[hondarider188]

Re: crankshaft key broken?

where can i find a key at and are they all the same size with different hp or change in the years.

 

[jbjennings]

Re: crankshaft key broken?

The keys are specific to the model. Can be gotten from any BRP dealer or online at various places. Iboats may even have them. Part numbers can be found online. Marineengine.com has parts diagrams that go back to 1955 for all OMC outboards. You can get the part number there and see if they have it here at iboats. Or.....
Later,
JBJ

 

[hondarider188]

Re: crankshaft key broken?

I found a key on marineengine.com but I am still wondering on how do you remove and replace the key. do you need to take apart the entire driveshaft or does it just slide on and off.

 

[Tim Frank]

Re: crankshaft key broken?

Step one is to get the flywheel off.

 

[boobie]

Re: crankshaft key broken?

Im' confused. Why do you keep saying "drive shaft" ? If you mean crankshaft that's fine.

 

[Chris1956]

Re: crankshaft key broken?

Generally the woodruff keys are half-moon shaped. If you tap on the top part of the broken key with small code chistle, at a 45* angler, you can usually coax it out of the crankshaft. Spray it with some penetrating oil as well.

 

[hondarider188]

Re: crankshaft key broken?

Ok but how does the new one go in does it just go right pop right in like it comes out

 

[jbjennings]

Re: crankshaft key broken?

You have to get it perfectly aligned over the slot, and tap it in gently. The key needs to seat fully in the slot, and be perfectly parralel to the centerline of the crank.

 

[hondarider188]

Re: crankshaft key broken?

Thanks for all the help

 

[Tim Frank]

Re: crankshaft key broken?

You have to get it perfectly aligned over the slot, and tap it in gently. The key needs to seat fully in the slot, and be perfectly parralel to the centerline of the crank.

Was about to post and say that this is wrong.....then I checked and a good thing, too.:facepalm:

I just did a full ignition R&R on a '75 6HP 'rude....OEM manual is clear that the key-flat needs to be aligned parallel with the TAPER.

My '90 8 HP 'rude OEM manual is just as JBJ says, set parallel with C/L of C/shaft.

Is this a HP thing...or...a vintage issue...or just random?

Obviously you need to get the actual spec for your particular motor, but this surprises me that there is a difference.

Anyone have any idea why the variance?

 

[boobie]

Re: crankshaft key broken?

Tim, I've ran into this same situation before too. The only thing I can say at this time is have the correct manual for the mtr you're working on.

 

[hondarider188]

Re: crankshaft key broken?

thanks for the help!

 

[hondarider188]

Re: crankshaft key broken?

well i think i might finaly come around to replacing the key i ordered a new off of marineengine.com and how do align the key and what do i align the engine with? i cant find a service manual so if anyone has one and know what to align it with i would love to know.

 

[kfa4303]

Re: crankshaft key broken?

HI hondaraider188. The new key is sort of a half circle shape. You'll want to reinstall it per JBjennings' instructions. Because the top of the crankshaft is tapered, but the key goes in parallel to the CENTERLINE of the crankshaft the top of the key will protrude out and away from the taper, while the bottom part of the key will more or less be flush with the wider base of the crankshaft. The flat, vertical edge of the key should be parallel to the center line of the crankshaft at this point. There is nothing to hold the key in place other than friction, so be careful when lowering your flywheel down on it as they can often fall out or get knocked out of their proper position. Reinstall the flywheel nut to the proper torque spec, and you should be good to go.

 

[hondarider188]

Re: crankshaft key broken?

do you think its worth replacing if the engine is running good? or do you think i should replace ti anyway. and will it improve performance?

 

[wilde1j]

Re: crankshaft key broken?

The key establishes the correct timing. With a sheared key, you have no idea where the timing is.

 

[jbjennings]

Re: crankshaft key broken?

If the engine is running good, and you haven't had the flywheel off, how do you know the woodruff key is broken? In you first post, you said it's broken. I'm beginning to wonder what key you're speaking of. Also, you did say driveshaft, rather than crankshaft. Of which do you mean?
I'm totally confused. If you're woodruff key was broken, you're engine couldn't possibly run good.
JBJ

 

[hondarider188]

Re: crankshaft key broken?

sorry for the confusion i wasnt sure what anything was called at first but it is in woodruff key on the crankshaft and i had hte flywheel off when i was replacing the entire ignition system and it isnt totally broken just sheared.