Water Pump Drive Gear Snapped Off Crankshaft!

[kxpegger]

Is this a common failure point? The engine was assembled by Service Honda!

The last few rides I was experiencing quite a bit of pinging but thought it was bad gas. Then I noticed it was puking about 150cc of coolant per ride. I pulled the rad cap and saw that there was no coolant flow.

Hope I didn't roach the top end too!

Also after I pulled the clutch cover my exhaust valves would barley move. Had to use a mallet and gently tap on the actuator rod to move the valves! I thought it was way down on power but havent been on the bike for over six months!

Looks like I'll be pulling the top end apart for sure!

Looking for suggestions to remove the broken part of the drive gear from the crankshaft. I'm assuming some heat and an easy out but without damaging the crank seal.

I did have a little good luck too as there is no other damage in the clutch area.

http://www.youtube.com/watch?v=ZPalL_FM7Mc

Update! The micro fiche makes it look like the water pump spur gear is press fit into the crankshaft? Looks like I may have to drill a hole and tap it! Then maybe some heat and create some type of shield to keep the heat away from the seal? Screw a bolt into the hole I tapped and use a slide hammer to pull it out?

Sure could use some help on this one. I don't trust any locals around here to do it thats for sure!

[81cr450]

Oh man that sucks.

The drill tap & slidehamer sounds like a good idea, might be a real PITA if that is hardened steel which I'd guess it is. When we weld the pick-up tube to oil pumps we use a rag soaked in cold water to try to keep the heat out of the pump, seems to work fairly well. I'd pull the gear & wrap directly on the crank though.

Thinking of that hardened steel if you cant drill & tap it you could drill a hole in a piece of plate & try welding it to the end of the nub thats left in the crank so you have something to grab it with maybe?

[kxpegger]

Oh man that sucks.

The drill tap & slidehamer sounds like a good idea, might be a real PITA if that is hardened steel which I'd guess it is. When we weld the pick-up tube to oil pumps we use a rag soaked in cold water to try to keep the heat out of the pump, seems to work fairly well. I'd pull the gear & wrap directly on the crank though.

Thinking of that hardened steel if you cant drill & tap it you could drill a hole in a piece of plate & try welding it to the end of the nub thats left in the crank so you have something to grab it with maybe?

One of my riding partners presently owns 5 different year KX500's and has had more than one for the last 18 years. I asked if he had ever experienced this? Nope! Just my bad luck!

Yeah! Definately going to have to keep that seal cool. I like your idea of a cool rag and then maybe some type of ice water drip onto the rag for some insurance? Cant tell by the micro fiche but it looks like it goes inside the crank at least 1/2".

[sandblaster]

I have had my hands on many K5's over the years and have never seen that happen.
Sorry to see it.
I think it's just a fluke.
Anyone else seen that?

[Larry Wiechman]

 Can you post a photo?
 
 If you use a welder, be careful where you place the ground clamp. Do not let current pass through bearings.

[5hunrooster]

This is what happened to me when I bought my 500. I couldn't figure it out. I took it for a couple 10 minute rides, it would start pinging and would notice a trail of coolant following me back. I took the water pump cover off and the impeller was spinning freely. I tried drilling and tapping but the tap would not start into the shaft of t.he gear. So I had to drill it out as much as I thought was safe to not damage the crank and tried to put the new gear in but, it IS a press fit. I tried the heating the crank end and putting the water pump shaft gear in the freezer but it didn't work. So I was frustrated one night, and after having a couple of thirst quenching Budweisers I gently started it in with a small hammer, then hit it square a few good times with a sledge hammer and perfect, it went all the way in until the gear was flush against the end of the crank. Since then, it has worked great.   

[kxpegger]

Can you post a photo?
 
 If you use a welder, be careful where you place the ground clamp. Do not let current pass through bearings.

http://s155.beta.photobucket.com/user/peteegger/media/024_zps2c13489e.jpg.html?sort=3&o=0

http://s155.beta.photobucket.com/user/peteegger/media/023_zpse2da7a78.jpg.html?sort=3&o=1

[81cr450]

This is what happened to me when I bought my 500. I couldn't figure it out. I took it for a couple 10 minute rides, it would start pinging and would notice a trail of coolant following me back. I took the water pump cover off and the impeller was spinning freely. I tried drilling and tapping but the tap would not start into the shaft of t.he gear. So I had to drill it out as much as I thought was safe to not damage the crank and tried to put the new gear in but, it IS a press fit. I tried the heating the crank end and putting the water pump shaft gear in the freezer but it didn't work. So I was frustrated one night, and after having a couple of thirst quenching Budweisers I gently started it in with a small hammer, then hit it square a few good times with a sledge hammer and perfect, it went all the way in until the gear was flush against the end of the crank. Since then, it has worked great.   

So what your saying is that the hole in the crank is deep enough to swallow an extra stub, correct?

[5hunrooster]

I'm not sure about that, I just tried drilling it out until it looked like it was all out of there

[don46]

I had one that had teeth missing on an Ebay motor, so I was going to replace it, Icouldn't get the gear out so I set the crank aside and used a different one. I'm sure this is an interference fit and requires heat and cold to assemble, and if I could get it out I'd let you know.

to answer your first qquestion I have never seen one fail, the one I had surely had something go through it to cause it to lose teeth, and even then it didn't break.

[kxpegger]

I've searched cyberspace with little success.

Plan #1 is to have a friend of mine machine a drill jig on his lathe that will fit over the crankshaft end and allow me to drill a hole keeping everything centered. Tap the hole and place a grade 8 bolt in the broke off piece after tapping. Design a heat shield to keep direct heat away from the crank seal. I will also use welders heat sink to keep the heat away. I found some stuff that's called Cool Blue. I will try not to get temps above 275-300F by using a digital temp gun I can borrow from work. I will then use a slide hammer and hopefully it will pop out. I've researched what you need to drill and tap hardened metal.

Plan #2 will be to take it to a local machinist who is also a dirt biker and understands all of the concerns. Silver State Machine of Las Vegas.

Plan #3 is split the cases, heat the s**t out of crank end and use a drift to knock the broken piece out inboard because I think the inner bore of crank end is the same size all the way through the crank.

Plan #4 as an absolute last option is buy a new crank!

[USMC 500]

I'm guessing you've already spoken with Service Honda on this since they supposedly assemble each engine piece by piece from OEM.  Hence, why they are so expensive.

[Klammer]

There are companies that specialize in broken bolt and screw extraction. They use a process called EDM. They can get your stud out and not heat up the seal. If you have problems locating this service, talk to machine shops. They often use these guys or know of a machine shop that has EDM.

[kxpegger]

There are companies that specialize in broken bolt and screw extraction. They use a process called EDM. They can get your stud out and not heat up the seal. If you have problems locating this service, talk to machine shops. They often use these guys or know of a machine shop that has EDM.

Thanks! Looking to see who in Las Vegas may be able to do this!

[kxpegger]

I'm guessing you've already spoken with Service Honda on this since they supposedly assemble each engine piece by piece from OEM.  Hence, why they are so expensive.

Haven't contacted SH. I would be surprised though if they were building the crank assembly opposed to ordering them complete. I have established that the spur gear is a press fit though.