overheat alarm

[pstephens46]

Anodes are changed because they are important. They protect the interior of the engine while running. Not sitting, tilted up. If they fall apart when removing them then they need to be changed more often. Like a Suzuki.....

[gsdanno1]

here are the latest and , since I'm at a loss , probably final temps . Did 1- 5 mile run @ WOT , temps went to 225 on YDS . I didn't have heat gun with me on this run . Water was a bit shallow when I left the dock , so I had my jackplate up about 3" (which I forgot to lower before getting on plane) I noticed , right before the temp alarm went off I was revving 5400 rpm , which my boat never does . At this point the temp on YDS was 207 , but the alarm still went off . I'm assuming it was due to a cavitation problem from the jackplate being raised. The alarm never went off the rest of the day . After going back to the dock , again @WOT , temp was 221. I got the heat gun , made a little shorter run where the temp only got to 207 and here are the temp readings at idle :Thermostat - 132 , pressure valve - 98 , Head portside @ top -172 , bottom -153. Head starboard top - 174 , bottom - 170 . At this time YDS was at 192 . I stuck my hand in the stream from the telltale and it felt lukewarm to me . I also discovered that my speedo is actually within about a half a mile an hour of my GPS .

[pstephens46]

I am forgetting what Rodbolt told us. Does the thermoswitch and thermosensor have to agree to get an audible or would that trigger the rpm reduction mode?

The engine never went into rpm reduction, correct? No codes?

So a thermoswitch triggered the audible? I am guessing. Wonder which head if this is true?

[gsdanno1]

From what I understand , the Engine Temp switch , at the top of the powerhead under/ near the flywheel is what the ECM reads the temp from . The engine has NEVER gone into rpm reduction , nor has it posted a code . As far as which head , I'm not understanding , thought I only had one

[pstephens46]

From what I understand , the Engine Temp switch , at the top of the powerhead under/ near the flywheel is what the ECM reads the temp from . The engine has NEVER gone into rpm reduction , nor has it posted a code . As far as which head , I'm not understanding , thought I only had one

Yep. Brain fart.
Thermosensor reads temp for YDS, top of engine. Thermoswitch located in cover of thermostat, i.e. the two wires. Rodbolt says either can trigger alarm. If both show overheat, a code is stored and I believe rpm reduction.
Unless your sensor is out of wack, I am guessing your switch triggered the alarm. And I believe you didn't have the temp gun to check that area when alarm happened.

[fairdeal]

Rodbolt says either can trigger alarm. If both show overheat, a code is stored and I believe rpm reduction.
Unless your sensor is out of wack, I am guessing your switch triggered the alarm.

The ECU allows the logic to be fairly complex, and for all we know, slightly different for any model ECU.
I've never seen a full explanation, and a Yamaha chart that Boscoe has shared is IMO overly simplified.
At least for my F225txrd ECU, which reacts differently depending on correlation between the block sensor and cooling water switch.

It seems like they have provided for a distinction between a "simple" overheat - losing water flow, but the block temp is normal
vs
some scenario which allows the block temp to get well over normal operating range.

In the "simple" case, there's an audible, but no code stored (and IIRC no rpm reduction)

that is what I have seen with weeds/plastic bag on the water intakes

I imagine a jackplate could easily achieve the same result

[gsdanno1]

I pulled both sensors and thermostat and they all tested fine.

[gsdanno1]

previously , when I ran the boat at 4400 rpm in neutral at the dock , the temp at the engine temp switch location was 195 with the gun

[99yam40]

I am sure running a motor in gear with a load is going to be different than in neutral with no load on it.
Takes more fuel to carry a load, more fuel you burn the more heat IMHO


time to use it and enjoy it now

[gsdanno1]

The thermoswitch and thermostat seem fine , they read about 132 after 8 miles @ WOT , my high reading is at the thermosensor , just below the flywheel. Can I do the same thing , pull switch and start motor ? And if so , will I have to wait until the thermostat opens to see any water flow ?

[pstephens46]

going to make another run either this afternoon or tomorrow , I'll post results , but I don't think it will change from the 216 that was on the YDS last week. When I changed the internal zincs , the water jackets looked great , no corrosion , same at the thermostat , and the pressure valve. The only thing I can think of is that there may have been a piece of one of the zincs that dislodged and is stuck somewhere in the head, but heat gun temps did not indicate that

Update on F150 operating temps.

Ran today at 5900rpm for about 7 minutes. YDS showed 219 degrees. Water temp was 78 degrees according to Lowrance.
New impeller in Dec 2016. Not worried about it. Just information.

[phillip1@reagan.com]

I have a 97 225 hp Yamaha two stroke that overheats it idling if I handled it over a minute and a half to two minutes replaced water pump impeller and thermostats

[99yam40]

you need to start your own new thread, with all of your info.
not add to someone else's old thread.

[phillip1@reagan.com]

Don’t know how to do that

[99yam40]

click on the New Topic button on the upper left side of page.
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