GreenHornet763
Seaman Apprentice
- Joined
- May 30, 2011
- Messages
- 36
1974-76 15hp johnson
So I did a compression check manual pull start (motor has electric start), 68 on both cylinder cold start. Thought had a bad carb because it woiuld literally take a minute on the electric start to start and run for about 5-10seconds then dies. I notice no water pumping out of the tail. Checked water pump and impeller seems decent, the water pump was smooth with no warping, i changed out with a new impeller. Still hard starting, changed new spark plugs, still hard starting. checked if both plugs have spark, both turned out nice and blue. Tonight i took off head and there seems to be no damage to cylinders and pistons, I pushed down on the piston to see if there's any play but both cylinders had none.
I was clueless, then i didnt see a thermostat which i assumed most newer johnson's would have it but not this model. When i opened the plate from the head to remove the thermostat, i notice one of the water channels were moist and other side was dry (seems to have a blockage or thermostat not opening). Upon further investigation, i notice plastic little pieces in front of thermostat. Conclusion would be there's a blockage somewhere and water is not spitting out of the tail. Maybe need new thermostat or clean the water tubes for blockage? Any tips or advice is great appreciated!
GH
So I did a compression check manual pull start (motor has electric start), 68 on both cylinder cold start. Thought had a bad carb because it woiuld literally take a minute on the electric start to start and run for about 5-10seconds then dies. I notice no water pumping out of the tail. Checked water pump and impeller seems decent, the water pump was smooth with no warping, i changed out with a new impeller. Still hard starting, changed new spark plugs, still hard starting. checked if both plugs have spark, both turned out nice and blue. Tonight i took off head and there seems to be no damage to cylinders and pistons, I pushed down on the piston to see if there's any play but both cylinders had none.
I was clueless, then i didnt see a thermostat which i assumed most newer johnson's would have it but not this model. When i opened the plate from the head to remove the thermostat, i notice one of the water channels were moist and other side was dry (seems to have a blockage or thermostat not opening). Upon further investigation, i notice plastic little pieces in front of thermostat. Conclusion would be there's a blockage somewhere and water is not spitting out of the tail. Maybe need new thermostat or clean the water tubes for blockage? Any tips or advice is great appreciated!
GH