OX66 Overheat alarm

[craigpeters]

I've got a 2003 OX66 200 HP that gives me a overheat alarm then goes into protection mode. It happens at idle, in gear within 5 minutes. I've had the impeller and thermostats changed. Any ideas?

[yam911]

Check the pressure control valve. Assumption being that it runs fine at cruise power.

[craigpeters]

Yes, it runs fine if you give it some gas, above idle. Then the alarm goes off. Then I'm fine at any other speed. It's just at idle, in gear when I'm mapping or scouting with my graphs.

[craigpeters]

How can you tell if it's bad?

[21XDC]

Replace the poppet/pressure relief valve with the new "Mushroom head" style.... Cheap and easy. 10 mm socket and flex extension. If this does not fix it, You may have a bad temp sensor on the heads like I did before... Mine would go off prematurely.

[HookedAgain!]

I agree with poppet valve...

[craigpeters]

Replace the poppet/pressure relief valve with the new "Mushroom head" style.... Cheap and easy. 10 mm socket and flex extension. If this does not fix it, You may have a bad temp sensor on the heads like I did before... Mine would go off prematurely.

Where would I find the "mushroom head" replacement?

[21XDC]

Call SIM Yamaha....

[21XDC]

[JoeFriday]

Change the impeller housing while you are at it. They get worn over time and will lose pressure. Had the same issue on mine. Poppet didn’t fix it, but the housing did.

[craigpeters]

Thanks everyone