Yamaha S130TLRX Overheat signal and starter spinning!!

[Flybouy6]

Gents,

1999 YAM S130 TLRX Oil Injected 549 HRs No issues to date for me...two years...50 hours.

I received an overheat signal/buzzer yesterday after hitting 3000 RPMs for a couple of minutes. I immediately slowed to idle, turned the motor off and let it "cool". Prior to, I had a solid pee stream and over 10psi on my water pressure gauge. I repeated the profile to see exactly when it occurs and it is after and above 3000 RPMs for just a few minutes. Will run under 3000 RPMs all day. The motor is new to me, the PO had awesome maintenance records. Yearly WP changes, fluids, filters. Tstats were unknown.

I started with the low hanging fruit. Replaced Water Pump and Thermostats. Cleaned water jacket passages around Tstats. Inspected others with my tiny scope. A little scale but nothing major. The Tstats were cruddy.

Tested pump on muffs and took cylinder head temps with IR thermometer. All good. 140ish and balanced.

On the water test showed the EXACT same thing. Solid pee stream. Better psi at 15-20 before Tstats opened and dropped to 10+ after. Buzzer at/above 3000 RPMs and 2-3 mins at that RPM. No buzzer below.

Here's the kicker. I pulled the cowling to take temps. They were all at 145. Balanced. BUT the starter motor was running!!!! The solenoid did not engage, but the starter motor was running. I then heard some weird electrical "ping" and the starter motor stopped. I disconnect the pink butt connector at the starter and the buzzer stopped.

I shut it down to see if I could repeat the events. This time I disconnected the temp sensors one at a time on each head to see if the sensor(s) was bad. Same, same. Definitely electrical. Rectifier?? Starter Relay?? Martians??

I idled back to the dock with my fishtail between my legs.

Rodbolt!!! Ideas???

[FabricGATOR]

How do you know it was overheat alarm? Do you have the digital tachometers and the thermometer symbol was flashing?

On my sx150's I get the same alarm when my oil system has a discrepancy, but the oil level gauges (on that same digital tachometer) flash, indicating an oil system fault.

The starter running thing is odd, possibly a stuck solenoid or something. I have not heard of an alarm for the starter remaining engaged... was it by any chance a particularly hard cranking starter situation to get the engine running? Did it seem to crank normal speed or did it crank slow by any chance?

[Flybouy6]

I have digital gauges with both Temp and Oil level ( three LCD type ). The TEMP bar was flashing and the buzzer was sounding. No OIL bars flashing.

The starter only ran intermittently. The starter did not start running right when the alarm went off. It would start and stop on it's own after the alarm went off, and not at all if just remaining below 3000 RPMs. No solenoid engagement. Just the starter motor spinning. No issues starting.

Update on trouble shooting.

I pulled the Thermo switches and tested them. Closed at 185F and opened back up at 160F. Within spec.

Checked compression to check for head gasket leaks. 130,127,130,123.

The only items left in the "overheat" troubleshooting column in the shop manual are:

Charge Coil

Pilot Screw

It could be a pin hole leak in the cylinder head gasket that only reveals itself at high RPM, but doubtful. My gut says electrical.

I do not believe the engine is overheating. With the starter motor issue it has to be wiring. Anyone had issues like this with the ignition switch?

[99yam40]

I would think a bad place in harness or harness connector shorting wires together, but a bad ignition switch could be possible.
But never heard of one doing this

[Flybouy6]

Forgot to mention I checked the PRV valve as well. It had a very small amount of crud on the spring side, but nothing on the head side and the grommet was pretty clean.

Any other ideas before I pull the water jacket covers?

Any recommendations on sticky/frozen bolts as I am sure there will be. Heat? PB Blaster? I see the torque specs are pretty light, so the bolts probably can;t take much torque.

[99yam40]

I would chase the electrical problem 1st.
there is a chance the motor is not overheating, and your electrical problem is doing something to set the alarm.
A starter that energizes while motor is already running is not good for any part of motor

anyway if you find and fix the electrical problem and it still over heats then deal with that