Hey everyone, new here, hope you can help me out.
Now I grew up working on 2-stroke motorcycles, and my Dad was a mechanic at a motorcycle/ATV shop for years.
So not a novice to engines, and this has us stumped
I picked up a 1991 25hp Evinrude, and I have not gotten it to run for more than 10 minutes at a crack yet.
It overheats, and I can not figure it out.
overboard indicator and water outlet both flowed
1st try - check thermostat, stuck shut with a piece of gasket - test run overheat.
2nd try replaced water pump - old was install wrong, that is where the gasket came from - test run overheat
tried backflusing water thru the thermostat hole and it stopped flowing, hmmmm
3rd try pulled the engine apart (covers) big glob of silicone in the water jacket around the cylinders - bingo!
cleaned it out, - test run overheat! - but I noticed this time that a lot of water was bubbling out the lower unit holes.
Pulled the power head again, checked the water inlet tube going into the head, and it was silicone in place with o-rings and all messed up.
Got that all cleaned up, and replaced seals etc. - water flows even better now - and OVERHEATS!!!!
I have torn the covers off again, can not find any blockage.
Compression on both cylinders is 100psi, it starts on the 1 or 2 pulls, and runs great until it warms up, so I don't think it is engine mechanica, I think it has to be water flow. - and yes the new t-stat opens in 150deg water.
And my heat gun verifies the motor is getting hot 400deg+ on the head, so it is not a bad overheat switch.
Any help is appreciated.
Now I grew up working on 2-stroke motorcycles, and my Dad was a mechanic at a motorcycle/ATV shop for years.
So not a novice to engines, and this has us stumped
I picked up a 1991 25hp Evinrude, and I have not gotten it to run for more than 10 minutes at a crack yet.
It overheats, and I can not figure it out.
overboard indicator and water outlet both flowed
1st try - check thermostat, stuck shut with a piece of gasket - test run overheat.
2nd try replaced water pump - old was install wrong, that is where the gasket came from - test run overheat
tried backflusing water thru the thermostat hole and it stopped flowing, hmmmm
3rd try pulled the engine apart (covers) big glob of silicone in the water jacket around the cylinders - bingo!
cleaned it out, - test run overheat! - but I noticed this time that a lot of water was bubbling out the lower unit holes.
Pulled the power head again, checked the water inlet tube going into the head, and it was silicone in place with o-rings and all messed up.
Got that all cleaned up, and replaced seals etc. - water flows even better now - and OVERHEATS!!!!
I have torn the covers off again, can not find any blockage.
Compression on both cylinders is 100psi, it starts on the 1 or 2 pulls, and runs great until it warms up, so I don't think it is engine mechanica, I think it has to be water flow. - and yes the new t-stat opens in 150deg water.
And my heat gun verifies the motor is getting hot 400deg+ on the head, so it is not a bad overheat switch.
Any help is appreciated.