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Jason, Marine Mechanic
Category: Boat
Satisfied Customers: 16102
Experience:  Degree in Marine Technology. Gas and diesel marine mechanic.
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I just purchased a boat with a 15hp, 4 stroke 2010 model Yamaha,

Customer Question

i just purchased a boat with a 15hp, 4 stroke 2010 model Yamaha, put it in the water the first time (pretty swift river), had a 2.8 mile trip (thank goodness downstream). about 1.5 miles in, engine started choking down, looked and the red light for water temperature was on. Had water coming out the hole in the back when I started, but was not when the light was on. would run only on low throttle then not run at all. would it be the water pump, or does it have a thermostat. the water is 58 degrees! if it is the water pump, how hard is it to change?
Submitted: 2 years ago.
Category: Boat
Expert:  Jason replied 2 years ago.
Hello my name is ***** ***** am I speaking with?
Expert:  Jason replied 2 years ago.
Do you have any history on the engine?
Expert:  Jason replied 2 years ago.
The engine does have a thermostat. However, on the impeller, that is maintainence item and needs to be changed every other year. They are just rubber, so they do get stiff and loose their ability to pump over time. If to much time goes by and the impeller is not replaced, it will eventually start to fall apart, and shoot bits of rubber up into the powerhead, where it will clog the engine. So the idea here is to replace it before it fails, and not wait until afterwards.
Expert:  Jason replied 2 years ago.
What I do in the shop is a cooling system service. On something like this it would run about 200-225. What I do is replace the impeller, it is always standard operating procedure to change the thermostat at the same time. And while it's all apart I flush the block out with a garden hose to clear any possible obstructions.
Expert:  Jason replied 2 years ago.
As far as is it easy to do..... The thermostat is easy. On the impeller. The lower unit has to be removed in order to access it. Removal is easy. Changing the impeller isn't to bad either. However, what is very tricky and where people run into trouble when they have never done one before Is installing the lower unit back into place. When installing the lower unit, the drive shaft, the water tube and the shift shaft all have to be lined up correctly. And the trick is you can't see any of it, so it all has to be done by feel.
Expert:  Jason replied 2 years ago.
And this is where people get stuck. Usually what happens people will not get the shift shaft lined up correctly, and it will be stick in gear. On top of that, if the gear selector is not on the correct position when it is put back together, and the unit is forced to shift, typically the plastic parts of the shift linkage will break. And it really isn't any fun trying to remove all of that.
Expert:  Jason replied 2 years ago.
So that is where you stand with this one here. Did you have any further questions on the issue? -Jason
Customer: replied 2 years ago.
nope, will try to get it out of the river and take to a Yamaha shop
Expert:  Jason replied 2 years ago.
You are most welcome and I was glad I could help. Just incase you do not understand the way the website works (and some folks do not). You do have to put forth a positive rating in order for it to credit me for helping you. When ratings are not done, the website simply keeps your deposit and they will not credit me. Please let me know if you run into any problems or errors when trying to do it. If you do have a problem, just reply back "I rate Jason's service _______" and fill in the blank.
Questions do not lose out, so if you have to come back tomorrow or next week with follow up questions to this you still can even after doing a rating.