Coolant in crankcase = no fun

stainlesscycle

stainlesscycle

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So, I went to national enduro this weekend, bike was running fine. During 1st section motor got noisy, and generally just sounded like ass. Pulled to side of trail, noticed cylinder was super hot, pulled the plug and it was white. Popped radiator cap. Dry. Nothing. Dang. So got to watch lotsa bikes zip by while I wait for sweep. there were lotsa lotsa gassers. and just a side note - whoever was on row 78 or so with a black honda crf250. dang you're fast. caught our whole row in 5 minutes. the other guys on my row said he caught them in every section quickly. and a thumbs up top the guy on the old tr5t! and the klr650 :) (he was a couple rows ahead of us, but we caught him in a minute or two..) it takes balls to do a national on either of those bikes...

Anyways, fast forward to now. Drained gearbox, oil looks fine. Pulled crankcase drain. Coolant poured out. Dang. So I'm assuming head o-ring failure. I'm assuming I get to replace: crank bearings, seals, con rod. I have a spare top end so that's going on it. It got really hot so I'm assuming the piston is toast. Theres some weeping coolant at the cylinder head joint near the front head mount. Maybe head cracked. I doubt both inner and outer o-rings failed (there's coolant in cyl and outside cyl).

Bummer.
 
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yeah, well i bought it used, and knew the one crank bearing was starting to get a little loose - i had planned on tearing down anyways eventually to fix it.. guess eventually means now. at least it'll be all new inside, and i'll KNOW what's going on inside, instead of assuming the previous owner had a clue. at least it will be as good as or better than new...
 
A leaking head o-ring won't cause coolant to get into the crankcase.
Since coolant travels through the lower cases, you may have a center case gasket leaking.
 
Yes, the leaking head is likely the result of the high temperatures. The head and cylinder should be checked for warpage.

The base gasket seals a coolant passage as well, from the cases up through the cylinder.

Did the bike have a plastic impeller? If so, also the possibility that you lost that and things cascaded downhill from there.

Just an FYI, on the bearings, the '07 uses a two piece roller on the ignition side. This bearing runs a high clearance compared to the ball bearings you are used to on the older motors. You can detect what appears to be excessive radial play but it is normal.
 
Metal impeller. So Is there a crossover on the left bearing ? I thought it was 6206? And right is 63/28? I know it specs nj206 c3- is it just a switch to a higher load bearing roller? Is case / crank same and 6206 will work?
 
No 6306 in an '07 motor. Been this way since '02 in 250/300. I don't remember the # offhand but its a two piece roller. You will see when you get it apart, its easier to split but you will have to pull the inner race off the crank and press the new one on. IMO, this is a good setup, lots of hours on a couple 250s with no issues.
 
Sorry to hear about your bike. Not fun if you're competing. Will you miss many races while you are ripping her down?
Make sure you take some picture and share your finding with us.
 
HuskyDude said:
Sorry to hear about your bike. Not fun if you're competing. Will you miss many races while you are ripping her down?
Make sure you take some picture and share your finding with us.
Click to expand...

that depends on how fast my local guy can build the crank. i have a million things going on today - i can split a motor in about 1 hour. i can reassemble in about 2 hours. i have a local race this weekend, but i dunno if i can get it all together and get parts fast enough...
 
had a few minutes to pull the motor. looks not good. motor is definitely coming apart. pics will follow. gotta run and do some errands, i'll have to split it later today.
 
stainless,

Your not bad, you said 6206. I said 6306 because that is what has been in the older bikes that I was familiar with. From '02 (maybe '01?) through '07 they used the NJ206ET roller bearing, and in '08 went to the sealed 6206 ball bearings that have the same dimmensions as the NJ206ET, so same cases. So, you can go one of three ways: sealed 6206, open 6206, NJ206ET (all C3 clearance spec). IMO I would just put the roller back in, can't wrap my head around the sealed bearing idea. One more thing to go wrong.

FYI:

6306 - 30 x 72 x 19
6206 - 30 x 62 x 16
NJ206ET - 30 x 62 x 16

For rebuilding an older bike, I've used the M306 heavy duty version with extra ball and machined cage. Still running today in an '00! The M206 is another option. Also, now there are more ceramic and ceramic hybrid choices available than there were a few years back.

This is all relative to the 250/300 only.
 
GMP said:
stainless,

Your not bad, you said 6206. I said 6306 because that is what has been in the older bikes that I was familiar with. From '02 (maybe '01?) through '07 they used the NJ206ET roller bearing, and in '08 went to the sealed 6206 ball bearings that have the same dimmensions as the NJ206ET, so same cases. So, you can go one of three ways: sealed 6206, open 6206, NJ206ET (all C3 clearance spec). IMO I would just put the roller back in, can't wrap my head around the sealed bearing idea. One more thing to go wrong.

FYI:

6306 - 30 x 72 x 19
6206 - 30 x 62 x 16
NJ206ET - 30 x 62 x 16

For rebuilding an older bike, I've used the M306 heavy duty version with extra ball and machined cage. Still running today in an '00! The M206 is another option. Also, now there are more ceramic and ceramic hybrid choices available than there were a few years back.

This is all relative to the 250/300 only.
Click to expand...

i have sealed or open 6206 in stock. and nj206 on order, for delivery tomorrow.. what works better? i know that honda tried the roller for a few years, on a quad and had lotsa failures, so they went back to the balls...

welp, had to go do some banking, slowed me down a little bit. cases are ready to be split if i could get that dumb right crank nut off. it's lh thread correct? loosens cw. correct?


edit: got the nut. had to break out the 1" impact. cracked a 1/2" 30mm thin wall trying to loosen it.
 
stainlesscycle said:
i have sealed or open 6206 in stock. and nj206 on order, for delivery tomorrow.. what works better? i know that honda tried the roller for a few years, on a quad and had lotsa failures, so they went back to the balls...

welp, had to go do some banking, slowed me down a little bit. cases are ready to be split if i could get that dumb right crank nut off. it's lh thread correct? loosens cw. correct?


edit: got the nut. had to break out the 1" impact. cracked a 1/2" 30mm thin wall trying to loosen it.
Click to expand...

I am inside my cases for the first time (2002 XC300), and want to know how to pull/remove the bearing from the left side (the rollers). Any tips? I am lining up the heat and the hammer, it's just what drift to use on the outer race since it's so well nestled inside the case.
 
i'm putting in a open 6206. if the nj bearing has more play by it's nature, i would think that would add to vibrations, and transfer that vibe to the other bearing. plus i don't wanna deal with a 2 piece bearing. my crank guy is gonna remove the end stuck on the crank.
 
stainlesscycle said:
do you mean the case half of the bearing or the part that ends up on the crank :)
Click to expand...

The case half. I sent the crank off to RB Designs, hoping he can get the inner race off there, it's the outer that I'm having trouble wrapping my head around. Well, with my limited selection of bearing removal tools. I have the hammer, it's just the aiming part that is giving me fits. Everything else is out of both case halves, at least well enough to run them through the dis.. (ahem) I mean "parts" washer last night, going to attack that outer race this afternoon. Any tips or suggestions would be appreciated.
 
With the seal out, can you get a driver on the roller section from the ignition side? I warm the cases and use various drivers I made from brass or aluminum, whatever works, either with a mallet on the bench with a rag protecting the gasket surfaces, or in a press. They usually come out with a few strikes if the case is warm.

Like I said I think the roller is a good deal, I have had no problems. More running clearance likely would mean more vibes, but also more tolerance for bore alignment. They like oil too.

I guess your using what you have, but I'd go with the M206 if you want to run a ball bearing. My bearing guy used to supply Ty Davis the M series bearings for the Yamahas he used to run.

I hit the crank nut with a propane torch and a 1/2" impact does fine.
 
to remove bearing from case. make sure ignition seal is out.

break the polyamide cage and remove rollers/cage.

heat case gently with mapp/propane. it doesn't take much. i could still almost touch it with my finger...

from the ignition side, with a big flat screwdriver or flat edged drift. round one won't work. chisel may cut bearing and not really work. catch the lip of the bearing, and give a wack. rotate 180 and repeat. it came out pretty easy. use a rag to stop from marring any surfaces.
 
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