Overheat? Oil? Alarm?? Whats up?

[FabricGATOR]

before you get to squirreled out.
The OX66 engines DO NOT use a thermosensor for ANY alarm or indicates.
THEY DO NOT.
if your using a FMM meter and the red/white wire shorts it can cause funny stuff.

myself I would test the alarms while watching the visual indicates first.
then chase ghosts.

Hey rodbolt,

Thank you for commenting and taking an interest.
I see in the IPC that there are two thermoswitches and one thermosensor.

Am I correct the the thermoswitch's are open/close circuit for overheat alarm and the thermosensor is a variable millivolt or ohm value strictly for sensing a degº of temperature for use by the CDI or indicating on a console gauge?

The term FMM is that a Fluke Multi Meter or another piece of equipment?

Again thank you all for your assistance.

[FabricGATOR]

I checked to thermo switches and found them to be normally open.

I shorted the bullet connectors at the engine (pink to black) and noted an alarm without the temp indication flashing on either tachometer. All four were tested individually both with just the ignition on and also running, just in case it did matter.

I removed them, inspected behind the covers, no fault seen. reinstalled both from the faulty engine with the two from the operational engine. Swap. Will test run this evening.

Thermo sensor wires (both black /yellow) ohm at 18.6 port engine and 21.3 stbd engine with open continuity to ground.

All battery wires are clean and tight. (Suggested by local Yamaha tech.)

I do not see the red white wire that rodbolt directed me to. Where are they located?

Thank you.

[rodbolt17]

once again, at the risk of being wore arse out.
the thermosensor on an OX66 has NOTHING to do with any visual OR audible alarms.
alarm audible and visual are con*****ed by the thermoswtch's.

FMM fuel management meter.

said wire is in the FMM harness running to the flow sensors.

[FabricGATOR]

Big progress!

Last night we went on a test run (with a six pack of Corona and one lime).

I ran them long and hard and only had one instance of an alarm and protection mode operation. by the time I got her slowed down, the alarms silenced just as soon as I went into neutral.

Two things I can attribute to the change in results are A) I inspected, and cleaned with a shot of electrical contact cleaner to the inside of the rubber plug and reseated the thermoswitches. and also B) the previous owners electrician had a mess of the console, of which I spend a long hot day securing and tidying wires. While I was there, I disconnected and reseated the connectors from the dual panel key switch and all other associated Yamaha plugs looking for evidence of corrosion.

I wish I had opportunity to do a test run between cleaning up the console wiring and messing with the thermoswitches.

Sequoia, 99Yam40 and Rodbolt thank you for helping me to get this far. Now that I have a better understanding of the system and I have seen a change in results, I should be able to see this through to completion.

Rodbolt, I apologize for the confusion. I read and understood the first time that the thermosensor was not part of the equation. I only posted the values because I had taken them in being thorough.

[99yam40]

you need to get the overheat alarms and oil level alarms to sound and indicate so you can figure out if this is a real alarm or something weird happening.
Hard to chase if you do not get indications on gauges when you are suppose to

[FabricGATOR]

you need to get the overheat alarms and oil level alarms to sound and indicate so you can figure out if this is a real alarm or something weird happening.
Hard to chase if you do not get indications on gauges when you are suppose to

Yes, I agree. And that is my intention, but thank you for pointing that out, for everyone's sake.

As previously stated, on either engine, if I jump any of the pink and black wires going to the four thermo switches, I get an audible alarm and no flashing temp bar indicator on either digital tachometer. It used to work, I have seen it in the past.

I had (or have) an overheat issue. I performed a flushing operation using saltaway and a spare fresh water washdown system pump for recirculation. I treated the Stbd engine first for about two hours and then the port. I fell asleep and the port flushed for between five and seven hours.

On the next test run the port engine, overheat did not happen but the starboard continued, although I did sense I could run longer and harder before it would alarm.

This week (three weeks later) I performed an additional flushing treatment on the Stbd engine, determined to finally get this fault repaired. This is when I began to ask for your help with my alarms.

Somewhere between last month and last week, although it would continue to alarm and throttle back, I missed that the indication did not flash on the tach. Now I am not able to even trip it manually on either engine.

I will look back at rodbolt's explanation of the oil tank alarm switches and try to trigger an oil alarm and see if it indicates as designed.

Thank you all for your continued guidance.

[jb123]

ever figger this out ? if you need a great local tech, let me know