Yamaha 5 HP not peeing

[blackshear]

I also noticed that the thermostat was stuck in the open position after the new one arrived and I was able to compare both of them. It’s just another result from the damage caused by saltwater. Since my last post I have taken the fuel pump apart and decided to replace both diaphragms and gaskets plus a new fuel filter. Hopefully that is all that is wrong with this engine and will get the little 5 hp back in top shape. I have certainly put a lot of time into this engine and it has been quite a learning experience for sure. Thanks to everyone for your help.

 

[blackshear]

The fuel pump parts came today and I was able to successfully put it all back together. The assembly was a little tricky getting the diaphragm spring in place while being blind to properly positioning it with the block of front of it. Somehow it all went together and solved the problem of keeping the fuel primed. This project is done!

 

[Pappy]

The point of my observation about the thermostat was that it was not the source of your overheating.
If you look back at your post #6 that should become clear.
Second thing that was never properly determined was the actual operating temperature of the engine and was it ever, in fact, overheating.
Third, you were assuming that without the overboard indicator working (post from April 5th) that you must have a problem with water flow. Once again, that is no indicator of whether or not there is sufficient waterflow and, in fact, is not necessary at all. All it is there for is to tell you the pump is doing something not how well it is doing. When you think about it, when it was plugged up, there was actually more cooling water passing through your engine! Where some confusion may lie is that the indicator is not the only source for cooling water to exit the block....far from it! The majority of cooling water exits at the base of the powerhead where you cannot see it.
In your case without the above answers and knowing now that the thermostat was and has been stuck open for a while, your engine may have been cooling all along.
Having said that, what you did as far as preventative maint. goes was well worth it and you now know a bunch more about your engine! Well done.

 

[blackshear]

The point of my observation about the thermostat was that it was not the source of your overheating.
If you look back at your post #6 that should become clear.
Second thing that was never properly determined was the actual operating temperature of the engine and was it ever, in fact, overheating.
Third, you were assuming that without the overboard indicator working (post from April 5th) that you must have a problem with water flow. Once again, that is no indicator of whether or not there is sufficient waterflow and, in fact, is not necessary at all. All it is there for is to tell you the pump is doing something not how well it is doing. When you think about it, when it was plugged up, there was actually more cooling water passing through your engine! Where some confusion may lie is that the indicator is not the only source for cooling water to exit the block....far from it! The majority of cooling water exits at the base of the powerhead where you cannot see it.
In your case without the above answers and knowing now that the thermostat was and has been stuck open for a while, your engine may have been cooling all along.
Having said that, what you did as far as preventative maint. goes was well worth it and you now know a bunch more about your engine! Well done.

I completely agree with everything you say. When I first took the thermostat out I didn't realize it was stuck in the open position until I had the new one to compare it to. I did not check the actual operating temperature but i can tell you it was running very hot to the touch. After all the work was completed the engine is running much cooler to the touch, you can actually leave your hand on top on the motor while it is running now. I know that's not a good test but I never thought to try and measure the actual temperature. I wish I would have taken some pictures of all of the corrosion in the water passages before i cleaned them out to show how bad things were.

At least for now it is running very smooth and has a strong exiting water stream. Thanks again for all of the information and help you and everyone else provided.