Rm 250 engine coolant in bottom end help

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7/9/2018 10:23 AM

I bought a 2005 rm 250 from a buddy he bought it bike looked mint before riding he checked cylinder through the exhaust port seen that it needed nikasil and new topend sent cylinder and head to tom Morgan he milled the head for race gas redid cylinder new topend got it back and broke it in and 1 hour later the crank came apart , he got a new oem bearing and crank with hot rods rod since Suzuki doesn’t have oem cranks in stock. Sent topend back to tom Morgan he went ahead and had tom Morgan port the cylinder , and redo the nikasil again and new top end , get it back all back together and it won’t start takes pipe off and there is coolant in pipe/bottom end. Long story made short he is over it I trade him a mint125 for it and now I have it, I sent topend back to tom Morgan to check for any leaks and he says it’s hokding good pressure and doesn’t know why it’s leaking. When I have the pipe off the bike doesn’t leak when piston is top dead center when I stroke it slowly down, it drips from the top right of cylinder when looking through exhaust port, and when it gets half way down where piston is half way between exhaust port it gushes coolant out but stops once it’s below exhaust port or above it . Any help would be appreciated this bike has it all but this is a headache. Thank you Photo

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7/9/2018 10:52 AM

It could be head gasket, base gasket or center case junction is leaking.
Sounds like the crank cavity is full of water.
Have you done a leak test?

Paw Paw

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7/9/2018 4:03 PM

Paw Paw 271 wrote:

It could be head gasket, base gasket or center case junction is leaking.
Sounds like the crank cavity is full of water.
Have ...more

Thanks for insight I installed a new o ring on head not a gasket and new base gasket and bottom end was cleaned out perfectly , when I have pipe off I can see a slow stream above the exhaust port on right side when piston gets halfway down from exhaust port it gushes until it’s below the exhaust port and doesn’t do again until it cycles to the same position. Tom did a pressure test with topend and said it was holding good.

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7/9/2018 5:49 PM
Edited Date/Time: 7/9/2018 5:50 PM

The reason the fluid is showing when it does is that when the piston heads down it displaces the fluid in the crank case and forces it up through the transfer ports just like it does with the fuel mix when the engine is running. The crank cavity is full of fluid and something is allowing the fluid into that area. The engine needs a tear down to find the cause.

Paw Paw

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11/16/2018 7:29 AM

Once the cooling system was pressure tested on this engine it was found that the cases had been weld repaired due to the previous crank failure. The cases were not surfaced correctly and there was a substantial leak from the coolant passage in the crankcase into the crankshaft cavity. The cases needed to be welded and surface ground...problem fixed. The cylinder and head were not the cause of the coolant leak.

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11/16/2018 7:44 AM

Engine Guy #1 wrote:

Once the cooling system was pressure tested on this engine it was found that the cases had been weld repaired due to the ...more

Exactly, thanks again for your help bike flat rips and runs perfect now.

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11/16/2018 1:01 PM

Engine Guy #1 wrote:

Once the cooling system was pressure tested on this engine it was found that the cases had been weld repaired due to the ...more

Thanks for posting that...These "help " post are a lot more educational when they are concluded properly.

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