I have a Honda 25 hp outboard that I have had for a couple of years (bought used). Since I've had this outboard the coolant stream from the motor has always been flowing whenever the motor has been on.
The last time out I had some problems with keeping the engine RPMs up for an extended period of time. After a couple of minutes of higher speed operation it would start to cut out. I could idle it awhile and then it would be able to run a higher speeds for a short time before starting to cut out. I think that problem can be attributed to fuel tank venting (or non-venting). Anyway, by the end of several minutes of working that problem I noticed the coolant stream having intermittent flow. This was on the way back to the ramp.
Back at the house, while running it in a bucket of water, I tried some wire up the coolant outlet tube to check for blockage - no change. Only getting a drip out the coolant tube at this time.
So I go look at the thermostat. It had a good coating of scale and dirt and corrosion. I soaked it in some CLR and it cleaned up pretty good. I then tried the hot water test on the stove. I started with the water cool and took it up to boiling while the thermostat was in the pan - I noticed no change. I thought I should see it change position. So I ordered a new thermostat. The elements of the new thermostat were in a different position than the old one.
Next I look at the impeller. It looked OK but it has a few years on it and I figured since the boat is down I'd change that too to take that out of the question.
I put it all back together and start it up but no change. Still just a drip out of the coolant tube.
Any help out there on what I am seeing? First do I have a problem? As the thermostat cycles does it change the coolant flow out of the engine. Should there always be coolant flow out of the engine or does it depend on the thermostat position? What should I check next?
Thanks in advance,
Doug
The last time out I had some problems with keeping the engine RPMs up for an extended period of time. After a couple of minutes of higher speed operation it would start to cut out. I could idle it awhile and then it would be able to run a higher speeds for a short time before starting to cut out. I think that problem can be attributed to fuel tank venting (or non-venting). Anyway, by the end of several minutes of working that problem I noticed the coolant stream having intermittent flow. This was on the way back to the ramp.
Back at the house, while running it in a bucket of water, I tried some wire up the coolant outlet tube to check for blockage - no change. Only getting a drip out the coolant tube at this time.
So I go look at the thermostat. It had a good coating of scale and dirt and corrosion. I soaked it in some CLR and it cleaned up pretty good. I then tried the hot water test on the stove. I started with the water cool and took it up to boiling while the thermostat was in the pan - I noticed no change. I thought I should see it change position. So I ordered a new thermostat. The elements of the new thermostat were in a different position than the old one.
Next I look at the impeller. It looked OK but it has a few years on it and I figured since the boat is down I'd change that too to take that out of the question.
I put it all back together and start it up but no change. Still just a drip out of the coolant tube.
Any help out there on what I am seeing? First do I have a problem? As the thermostat cycles does it change the coolant flow out of the engine. Should there always be coolant flow out of the engine or does it depend on the thermostat position? What should I check next?
Thanks in advance,
Doug