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crank bearing failed in 10 hours

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I looked at a 2011 300 xc last November that needed a bottom end. The price was right so i bought it. I had a new hot rods kit put in by a reputable shop and everything ran great until friday. I noticed a faint noise coming from the stator side so I removed the stator cover to look inside. There was a lot of dirt and rust and i noticed the flywheel will move up and down a little if i lift up and down on it. It also makes a clunking sound when I do this.

I think this means the bearing failed. Is there any chance I can reuse the crank and just replace the bearings? It only has 10 hours on it. What would cause failure like this in such a short amount of time? By comparison I was told the oem crank had 175 hours on it when it was replaced

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I looked at a 2011 300 xc last November that needed a bottom end. The price was right so i bought it. I had a new hot rods kit put in by a reputable shop and everything ran great until friday. I noticed a faint noise coming from the stator side so I removed the stator cover to look inside. There was a lot of dirt and rust and i noticed the flywheel will move up and down a little if i lift up and down on it. It also makes a clunking sound when I do this.

I think this means the bearing failed. Is there any chance I can reuse the crank and just replace the bearings? It only has 10 hours on it. What would cause failure like this in such a short amount of time? By comparison I was told the oem crank had 175 hours on it when it was replaced

I would bring it to the shop and say "here, you screwed up, fix it."

Even the best mechanics make mistakes sometimes. Don't let someones mistake become your money pit.

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I would bring it to the shop and say "here, you screwed up, fix it."

Even the best mechanics make mistakes sometimes. Don't let someones mistake become your money pit.

I agree, who knows if they changed that bearing to begin with ? If i ever send anything of mine to be worked on i make sure they keep every old part that came off . Except my dog once i took him to the vet. 

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I agree, who knows if they changed that bearing to begin with ? If i ever send anything of mine to be worked on i make sure they keep every old part that came off . Except my dog once i took him to the vet.

My bike rarely sees a shop (I do all my own stunts...err...mechanic work) but if it did and then there was a failure of the part I had "replaced" without me touching it, I would not hesitate to argue to get it repaired correctly. Because, think about it, mechanic didnt change a $25 bearing, which could lead to the motor somehow grenading, resulting in a nice big hole in the case and a $850+ ebay purchase.

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I agree with lethalweapon.  Call the reputable shop to see if they will work with you.  I also agree that doing your own work is far more practical than having someone else do it.  Maybe not the first time, but the second, third and thereafter, you are not only saving a lot of money, you are sure you are doing it right.  

 

Other than that, nobody knows why that bearing went bad, or whether the crank is good.  Let us know what you find out.

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I agree with lethalweapon. Call the reputable shop to see if they will work with you. I also agree that doing your own work is far more practical than having someone else do it. Maybe not the first time, but the second, third and thereafter, you are not only saving a lot of money, you are sure you are doing it right.

Other than that, nobody knows why that bearing went bad, or whether the crank is good. Let us know what you find out.

Yeah, could be 1000 reasons why that bearing went. Anything from manufacturing error to idiocy...im leaning towards the latter.

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I'll call the shop when they open tomorrow to see what they say but I'm not sure it's their fault. I have the old parts so I know they replaced them and I'm not really sure what they could have done wrong to cause this. Theyre the fo to spot for most locals and ive used them in the past so i have confidence in their work. I've done this myself before it's pretty easy to split the case and sweat in new bearings. Assuming they did do it right is there anything else that could cause this?

I'm leaning more toward a bad flywheel side crank seal due to the amount of dirt inside the stator cover. I was really surprised by that btw. Are ktms prone to this? The rudder thing thats around the stator wires doesn't seal the hole very well where it enters the stator cover at all.

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aftermarket stuff is a crap shoot on qaulity. most likely the crank isnt damaged but i would have a competant shop inspect it and throw some dial indicators on. at a minimum i would put oe bearings back in. i have no idea where hotrods is sourcing the crank bearings but obviosly they werent up to the task at hand

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There it is. If there's excessive dirt in the stator area that likely caused the failure. Not hotrods bearings. But sure, youre right, i guess to you you always are huh?

Edited by zotis777

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I'll post a pic of the inside of the stator cover when I rebuild it. Its bad enough that im going to give them the benefit of the doubt on it but I'll rebuild it myself this time to be safe.

Does anyone know a trick to seal the stator cover water tight? My flywheel is totally covered in rust so water must be getting in and I fear it will take out another crank if I don't fix it

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I'll post a pic of the inside of the stator cover when I rebuild it. Its bad enough that im going to give them the benefit of the doubt on it but I'll rebuild it myself this time to be safe.

Does anyone know a trick to seal the stator cover water tight? My flywheel is totally covered in rust so water must be getting in and I fear it will take out another crank if I don't fix it

Maybe a thin coat of RTV on a new stator cover gasket.

Dude, dont make this your problem. Really. It isnt worth it. I am also more than capable of splitting the cases and replacing the bearings, but since I didnt install them and it failed, I wouldn't. Because it isnt my fault.

And besides, maybe the mechanic who worked on it knows something you dont. I would give it right back to them.

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seals are exposed to dirt all the time. swingarm, wheels, steering head all come to mind. they dont fail in 10hrs. unless they forgot to put the crank seal in then alittle dust should have no affect on it.  maybe the mechainc put the bearing in with a jackhammer. or just as likely is the hotrod bearing are garbage

 

put rtv on the gasket and rubber grommet where it pushes into the case. :prof:

Edited by harryhandshake
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Well one would hope the gasket would keep the dirt out, as is intended.....

I think it is the dirt in the stator side that caused the problem

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Well one would hope the gasket would keep the dirt out, as is intended.....

I think it is the dirt in the stator side that caused the problem

Unless its a pebble or two in the bearing, I cant see it causing that much damage in 10 hours.

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Why not? They spin Damn fast, and sand is an abrasive. If it was Sandy soil or sand then it could. Would you ever Sandblast a crank bearing?

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bottom end < > crankshaft bearings,  did they even replace them?  I've replaced many crankshafts without replacing main bearings

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