Wr250f broken impellar gear

Well started up the wr250 today and was going to ride it around the back yard a little.Everything seemed fine when I heard a strange sound. Not tearibly bad but diffrent. so I shut it off. i then noticed oil dripping pretty good. tjought drain plug had loosened up. Took skid plate off but that wasn't pt. i then noticed a hole on bottom of right crankcase cover under water pump.. Pulled it off and the impeller gear for water pump had broke in halve. . All crankcase bearings are fairly new as well as seals. No play or slop anywhwere. Is this a common accurance. I was going to replace cover and water pump, seals ect and be done. My question is should I be worried something else is wrong. Bike is not locked up and was running fine .It did not stop running but I shut it off as soon as I heard noise. Just wondering if the gear just broke?

nobody has had issues with this?

I'll take a shot:

Maybe just a random gear failure. I can't think of anything in particular that would cause it (I've rebuild a few of these). It could be that a chip from some other gear tooth (i.e. tranny, balancer), broke off but would not stop your bike from working. Or any other non-essential piece of metal.Then this piece got up between the impeller gears and broke them.

It could be that someone who put it together before had these gears misaligned, and forced the cases together, damaging the gear, but failure did not occur until later. Or they bent the shaft (not sure if this is possible) You would know if this is a possibility, based on history of the bike.

I would look everywhere you can in your cases for any extraneous chips. also, you might be able to reach into the center cases on the bottom with a small magnetic probe and see if you can pick up anything. You can also get access from the alternator side. Chips that drop to the bottom usually stay there though, so you could choose to let it ride.

Check the shaft for bent, if you can (doesn't seem likely)

Also, when you put the seals back in, the lip faces towards the water (pressure) side. It's kind of easy to confuse yourself about this (I like to think so - I did it).

- Toby

well it must have been a random failur. Put new crankcase cover, imellar gear and shaft in. rhode bike for 3 hrs today and no problems. Very relieved it was not anything more serious.

Did you recover all of the pieces of the gear? Mine made its way into the crankcase and got broken into smaller pieces. Discovered it when I changed the cam chain and found a gear tooth on the magneto, along with lots of filings. Fished out all the other pieces using a small magnet and suffered no other damage.

pretty sure I did. mine had a hole in the cover right under the gear which is wy it was leaking,(pouring) oil out.it looked like most of peices of the gear were still in the cover. Took flywheel cover off and nothing there. drained oil after ride and changed filter and no sign of metal.

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