2000 ox66 Water Temp Alarm

[floridaflatbed]

Ok Guys,

I replaced

Thermostats
Alarm Sensors
Water Pump
New and improved poppit valve
Removed heads and water jackets were clean and engine was clean of corrosion.

Installed Temp Gauge
Installed Water Pressure Gauge

Water Pressure runs steady at 20-25 LBS


infra red therm does not go over 135 degrees from all parts of both heads.

Alarm sounds and temp icon flashes at about 160 Degrees ( on the Gauge) at about 3000-3500 RPM.

Sometimes when the alarm sounds I can stop the boat and idle for about 2-3 minutes until alarm shuts off and start going again with no alarm for a good while.
Sometimes the alarm shuts off and doesn't come back on rest of day as long as I don't push the engine too hard..
I have yet to be stranded but its driving me crazy.

My Mechanic suggested running without thermostats for a while ( I haven't had an opportunity to try this yet)

Please hit me with your suggestions as to what to try next?

Nite-owl

[99yam40]

my brothers C60 has been doing this only when run WOT, last time it sounded we pulled the stat and found some chunks behind the stat.
only thing I can think of is when a lot of water is being pushed around under high RPMs that some junk is being pushed up and plugging off some important passage causing a hot spot that a temperature switch is seeing
did you shoot the areas at the temp switches or sensors that set the alarm while the alarm was sounding?

[rejesterd]

Ok Guys,
Sometimes the alarm shuts off and doesn't come back on rest of day as long as I don't push the engine too hard..

I don't know about your model, but on other models, the alarm won't sound unless you go over a certain rpm for a certain amount of time. Maybe someone who has your manual will have this specific info.

As to why the alarm is sounding with new thermostats and temp readings of only 135.. did you also replace the wiring for the cooling water temp sensor? Replacing that and the sensor would really only leave the CDI unit to point fingers at if the problem is electrical.

[floridaflatbed]

Thank You for the responses.

I'm Going to take the boat out next week and when the alarm sounds I will disconnect the sensor off each head individually and see if I can isolate the alarm to one specific bank.

I'll post any results here in about a week or so.

[ausnoelm]

Kind of sounds like you have build up in the water passages, especially in the part the temp sensor fits in, remedy is to remove the heads and any other bits to gain access, drill out broken bolts, clean water passages thoroughly, reassemble and go boating.