200hp ox66 alarm troubleshoot HELP!

[Freddy29412]

I have 1999 that has done me well the past 5 years I've owned it.
Recently when I go above 3000 rpm I get an alarm that throttles me down with no warning on digital gauge(temp/oil). Nothing flashing.
I have replaced water pump, thermostats, water sep, and fuel filter on motor. I have ran w/o cowling and oil and fuel levels stay normal. Still same problem.
Can anyone assist?
Thanks

[99yam40]

To start out with I would test the temp and oil alarms to see if they set off the alarm and indicate as they should on the gauges before chasing other things just to make sure all that is functioning properly

[Freddy29412]

ok, I finally got out this afternoon with an infrared gun and both heads are running 170F when alarm sounds so problem found. Now, where to go from here? I have new thermostats and water pump was changed last Nov. and I've only put about 20 hours on it. I guess I'll inspect pump to make sure all is good there. What else could cause overheating?
THANKS!

[99yam40]

temp switch for overheat closes around 200F on my C40.
Maybe you should look at your service manual and get the specs

You still have not tested your alarm systems to see if they indicate properly when they set off alarms

[Freddy29412]

Yes, I did test both oil and temp. Oil alarm sounded and blinked on gauge when I drained tank. Temp alarm sounded but did not blink on gauge when I connected sensor wires(pink and black).
Temp is suppose to be 140F.

[bajakeith]

overheat

I would do an impeller..they don't like to NOT be used..and I also keep finding other shops not installing the "cup" and w/p housing bottom seal/O-ring with the proper sealant... I use evinrude/Johnson gasket sealing compound..good stuff,,,dosnt dry out and the omc triple guard grease beats all the others hands down !!! THE ONLY REASON THE OLD OMCS RAN WAS THEY HAVE AWESOME CHEMS!!! LOL................K

[Freddy29412]

Inspected water pump today and the YAMAHA kit I installed last Nov still looks good. I bit of sand so I cleaned it out, but impeller still had a lot of spring and all the O-rings, gaskets were great shape. Hopeful to get out tomorrow and run. Would there be something beyond water pump that could inhibit water flow?

[jb123]

Replace pump AND housing
Stats
Prv
Go use your boat

[99yam40]

Yes, I did test both oil and temp. Oil alarm sounded and blinked on gauge when I drained tank. Temp alarm sounded but did not blink on gauge when I connected sensor wires(pink and black).
Temp is suppose to be 140F.

stats start to open around 120 and are full open at 140, but I do not believe temp will run that low
Motor warmed up switch closes at 100 to 125
motor overheat closes at 194 to 204

Need to fix the problem with over heat not indicating and test overheat switch in a pot of water as you heat it up to see what temp it closes to make sure it is in spec

[Contender 23]

Over heating

Freddy, I had the same problem a few years back
Check all your thermosensor wires on top of the engine
For nicks or where the wire is rubbing against something
And has wire the insulation off the wire. If I remember mine was rubbing against the bracket on top of the motor that is used to lift motor.

[Freddy29412]

Wiring looks fine.
Both heads are running 60-65F when alarm goes off according to infrared gun.
So, do the temp switches just pull out...looks like they are just pressed in.
Is there a way to test Thermo switch on bottom of port head?

[Freddy29412]

Sorry!
I meant 160-165F

[MarkinNaples]

Freddy did you resolve your problem? I'm having the exact same issues.