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Johnson Model J15ECEC Overheated

ko4nrbs

Regular Contributor
Noticed the water was not coming out of the pee hole so I took the water pump apart. The impeller was only two years old and had not been used that much. The flappers on the impeller had all broken off. I replaced it and looked up in the water tube for pieces of the impeller but didn't see anything. Put in back in a barrel and it was pumping water out the pee hole pretty good. Took it out in the lake and after about 5 minutes at full throttle the motor died and locked up. After it cooled it freed up. Up until it overheated I was seeing water being pumped out of the pee hole.

Here is what I found:
1. Water pump impeller ok with no damage.
2. Pulled head and cylinders look fine with no scoring or discoloration.
3. Use compressed air to verify the water tube was clear. Also blew air down into the exhaust thru the small hole at the botoom of where the head mounts. No debris found either.
4. Thermostat was clear of any debris but looked like it wasn't opening when put in boiling water.

Based on what I found I think the thermostat failed to open. I will replace the head gasket and thermostat and try to start it. I hope the rings are ok and will run a compression check when I get it back together.

What do you guys think?
Bill
 
If the thermostat failed to open in boiling water it certainly is bad.------Very good test of it.----Most of them fail in the open position.--------So put it all back together and see how it runs.
 
I ordered the parts and will put it back together when they get here. I hope I dodged a bullet and the rings are ok. The top of the pistons look fine to. Was relieved the cylinder walls were not scored or burned up.
Bill
 
I ordered the parts and will put it back together when they get here. I hope I dodged a bullet and the rings are ok. The top of the pistons look fine to. Was relieved the cylinder walls were not scored or burned up.
Bill


I installed a new thermostat and head gasket. It runs fine now in a barrel. Looks like I didin't seriously damage the motor. Compression in both cylinders is 120psi. Pulled the flywheel and the electronics and wiring look fine. No melting or burns.

The smoke and smell when it overheated was a piece of plastic wire loom that had melted. The wires were ok.


Bill
 
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