coolant dripping from exhaust port

[Andrew Boundy]

Hey all.

My 250 EXC 2013 has stopped running. Following is what I observe (I’m not a tech).

1. There is a watery liquid dripping from the bottom part of the joint btween the cylinder head and the exhaust (exhaust port?). It is a light brown colour - smells a little like gas, bit oily - will not light by flame.
2. It drips after kicking over the bike - not if it is left.
3. My coolant level is down
4. If I let the bike site for 30 minutes I get 1/2 second of combustion (a few cycles I think) followed by complete death - nada.
5. spark plug and gas I believe are ok - makes sense with number 4 above as there is some catching (if very short)
6. There is no leak above the exh. port - I put paper there to test the overflow/frame drip etc. and it does not appear to be from there - it appears to be coming from the cylinder.
7. Happened after a 4 lap mx run by a friend who is faster than me on the bike.

So Perhaps coolant is in the combustion and that kills it? When it has sat, the water goes and it allows a min-cycle before the “wetness” kills the mixture?

If this is right (and it probably is not) - how would coolant get into the cylinder? I need to replace the exhaust connection o-rings as there was always a little leak here but it was oil before, not water.

Thanks - I can take it to a mechanic but trying to understand better so I can do my own work -sort of dds to the fun ?

A.

 

[Shhhh]

Head gasket went, or, oring in this case.  I had the same thing, but my crank had completely filled with coolant. 

Pull the head and I bet you’ll see the dots of coolant on the piston. Make sure there is little to no coolant in your crank, If there is, flush it with premix and try to get it out. 

 

Changing the orings is simple, and a good start to learning how to wrench on your bike.  

Edited October 13, 2019 by Poldies

[Andrew Boundy]

1 hour ago, Poldies said:

Head gasket went, or, oring in this case.  I had the same thing, but my crank had completely filled with coolant. 

Pull the head and I bet you’ll see the dots of coolant on the piston. Make sure there is little to no coolant in your crank, If there is, flush it with premix and try to get it out. 

 

Changing the orings is simple, and a good start to learning how to wrench on your bike.  

Hey Poldies - thanks for the info! I found Tokyo Off-road’s videos showing the o-rings (as part of a piston change) and your diagnosis makes sense completely - but having problems finding out how to inspect or flush the crank - is there some thick that doesn’t include splitting cases etc. (bit much for me that). Thanks again! A.

[Shhhh]

35 minutes ago, Andrew Boundy said:

Hey Poldies - thanks for the info! I found Tokyo Off-road’s videos showing the o-rings (as part of a piston change) and your diagnosis makes sense completely - but having problems finding out how to inspect or flush the crank - is there some thick that doesn’t include splitting cases etc. (bit much for me that). Thanks again! A.

Pull the cylinder too, that will expose the crank.  A top end swap is a good skill to have.  Follow the manual, get a decent torque wrench and give it a go!

[Andrew Boundy]

Just because I like a finish to a thread in case someone has the same question - the report:

I pulled the head and the inner o-ring was toast. The piston top and cylinder appeared OK - the head got a clean and was also OK. Compression tested cold 140 and a slow loss (cold). New coolant, new fuel. She didn't start - at all!

I checked spark - there was one. I re-jetted to 165 / pos. 4 and air-screw per manual (hot at seal level) - nothing! She was way too lean before (set for 7,000 ft!!)

I then pulled the exhaust which had watery crap in it (coolant). I replaced the exhaust o-rings to the cylinder (where the leak was) and the back-box coupler (because it came in the kit). Nada!

She had a BR8 spark plug - book says it should be a BR7 - so ordered and changed. Nothing until I tipped a little fuel into the cylinder where she fired and ran nicely after a few coughs - bit of messing with carb to do but she was much better. All good.

So - that's the resolution. Thanks to excellent people at TT who helped with info (plus by pal Peter).