Sheared woodruff key

[MuddyArgyle]

I was struggling with a non-start issue on my 2011 ec300. I decided to look at the flywheel just to see if anything looked off. I found a piece of metal in the flywheel slot, and sure enough NO metal where there is supposed to be the woodruff key.

Is it possible to fix this without pulling the whole motor apart? Do I need to replace the whole crank? I've heard about compatibility with cr250 motor parts? Alternatively is there a way to repair it without replacing/rebuilding the whole bottom end?

In the pic, I also notice that it's really oily in there, so I guess I'm replacing the seal anyways...

 

[MuddyArgyle]

Answering my own question

Okay, my momentary despair has passed, I've done some research, and I will answer my own question in case others find this post and are in similar positions. The key should be removable, and easily replaceable, and cost like $6, instead of the $600 I feared for a new crank assembly. That really would have been a shame considering I JUST rebuilt the top end.

To remove the key, you can tap on it lightly with a screwdriver to angle it around so that you can pull it out with pliers... or so several youtube videos and e-how article say. I haven't tried yet, but given my luck, it will be really tough to get out. That said, I feel like I should avoid hitting it very hard since that force would be translate through the crank bearings. I will report back with my success and/or struggles.

 

[Doc Brown]

You answered your own question quite well

All you need is patience and not brutal force, you will be able to tap the left over part of the woodruff key out. Once you have done that check the edges of the key seat. They can be sharp but should not look like the blade of a serrated blade of a bread knive. If the edge is looking bad you can go over it with a small diamond file but you should know what you are doing as you want the new key to survive an eternity

Replacing the seal seems to be a brilliant idea

 

[Neil E.]

carefully drill two small holes into the rubber seal opposite each other. Run in some self-tapping screws/wood screws/drywall screws enough to be secure. Alternately pull on them with pliers and you can walk the seal out. Get a new seal from a bearing shop and push it in with a large socket. If I'm remembering correctly the depth is 11mm, so any seal can work. Does not have to be 6.5 wide listed in the manual (I put in an 8mm wide double lip).

 

[hannesd]

as crank seal i'd go with a double lip seal...

 

[fred99999au]

One point of note. On my older non GG dirt squirts, I usually lap the rotor and crank without the woodruff key in place. I use fine valve grinding paste.

The taper itself should be driving the rotor, the key should only be there to locate it.

 

[Gasser Nate]

The current seal looks like it is in way too far as well. Flush with the case is fine.

 

[(F5)]

As said. Valve grind paste fine. Lap it back and forward. Clean. Repeat. Clean, new key.

Have areal good lok at the seal inner lips. If they are perfect and not leaking them learn to pull wheelies.