help...yamaha 5.7 motor running hot

[solocam]

I have the dreaded 5.7 yamaha sterndrive that is running 225 F on the guage. I recently changed the impeller and have good water flow up to the thermostat housing. I tested the motor in the lake with the thermostat in and it ran up to 225 F...thermostat out 225 F. As i said there is good water flow to the thermostat housing and none of the ports are blocked.

Idle = 225 F, running = 225 F....could there be a restriction and where do i look for it if you think there is one?

Please help...thanks. Any suggestions are greatly appreciated.

 

[45Auto]

Re: help...yamaha 5.7 motor running hot

Your boat is what, at least 10 years old? Have you ever replaced the exhaust manifolds or risers? They could easily be restricting flow and overheating your motor. Supposedly hard to find parts for them, good luck!

 

[solocam]

Re: help...yamaha 5.7 motor running hot

Its 15 years old and i have not replaced them since i dont want to pay 2600 bucks for a new set. I know that could be a problem but i am looking for a solution from someone who understands troubleshooting rather than someone who wants to post sarcastic comments.