2014 sho and engine temp gauge

[munchie]

I installed the cable to show engine temp on my lowrance. It seems to work fine, start up temp low, warms up to 120 or so, then when running reads 135 , 140 depending. Clearly working,

. However, when I was idling over a mud flat, worried about overheating, watching the reading, it never changed from 135, not one degree, but the overheat alarm went off. How can this happen?

I thought I would be able to see the temp rise so I could cut it off before alarm would sound.. seems I wasted my money on the cable for engine temp. Previous needle gauges on other motors would have.

Any thoughts

[jethro1]

Engine temperature seen on an NMEA 2000 device is based on a sensor that is on the top of the engine block. It is reading engine block temperature.

There are two over temperature switches that close when the heads get too hot. I suspect that a thermoswitch closed and caused your alarm while the top of the block was still relatively cool.

[munchie]

Engine temperature seen on an NMEA 2000 device is based on a sensor that is on the top of the engine block. It is reading engine block temperature.

There are two over temperature switches that close when the heads get too hot. I suspect that a thermoswitch closed and caused your alarm while the top of the block was still relatively cool.

Thanks, is there any way to have a temp gauge that will read in time to prevent this in the future

[FrankWhoa]

Update?

[munchie]

Haven't been able to stop using the boat long enough to take to the shop to get this done. We have two 250 shos with the exact issue of running hot while the gauge is still reading 130 ish. Will be on our to do list this winter.

[FrankWhoa]

Great. Let us know once you figure it out.

[munchie]

Great. Let us know once you figure it out.

Finally got the temp gauge installed per Jethro help. I think it will solve the problem since this sensor is in the water flow. I haven't run it hot to see and IDONT WANT TO, !!!!!

i do think that it is a design flaw on yahama when a enging can run hot, set off the heat alarm WITHOUT the temperature readout sent thru the outboards harness regestering any rise in temp.

I dont see any logic in putting atemp sensor on a cold spot on the head that wont monitor actually temperature increase

[jethro1]

Each head has a thermoswitch that will set an alarm if and when a head gets too hot.

In the top of the block there is a thermosensor that reports block temperature to the ECU. The ECU sends this data to a chart plotter. If and when the block gets too hot the alarm will sound. The sensor does more than just warn of an over temperature situation whereas that is all the thermoswitch does.

It is possible for a head to over heat with the block staying cool. It is possible for the block to over heat with the heads staying cool.

[Ranger007]

Can you post up the Yamaha parts used to make the head or water temp send to the LOWRANCE if possible? Yamaha links not working any longer. Motor is 250 SHO

I have the NMEA 2000 connected to LOWRANCE HDS & temp gauge displays but I can only assume it's block temp because I have had multiple "hot alarms" go off and the temp on the LOWRANCE has never went above 145 same with command link gauges Indicator stays between the "Cold" and "Hot" but alarm is going off.

On my HPDI I could watch the temp climb on the LOWRANCE before hot alarm

[FrankWhoa]

It is possible for a head to over heat with the block staying cool. It is possible for the block to over heat with the heads staying cool.

Do both sound at the key. Does the key alarm sound the same for both?

[jethro1]

Do both sound at the key. Does the key alarm sound the same for both?

Only one sound for a Yamaha warning signal. A constant horn blowing. Could be over temp or could be low oil pressure. Either of the two thermoswitches closing or the thermosensor indicating excessive temperature will result in the horn blowing. Steady state.

Now note that I mentioned the warning signal. Not to be confused with a caution signal. If there is too much water in the fuel filter cup then an intermittent beeping sound will be made by the horn. But only when the engine is in neutral gear. Shift it into gear and the horn will stop.

[munchie]

Can you post up the Yamaha parts used to make the head or water temp send to the LOWRANCE if possible? Yamaha links not working any longer. Motor is 250 SHO

I have the NMEA 2000 connected to LOWRANCE HDS & temp gauge displays but I can only assume it's block temp because I have had multiple "hot alarms" go off and the temp on the LOWRANCE has never went above 145 same with command link gauges Indicator stays between the "Cold" and "Hot" but alarm is going off.

On my HPDI I could watch the temp climb on the LOWRANCE before hot alarm

I had to install a dash guage as well as a sensor. works great. can watch temp rise and fall. lowrance engine temp stays constant. waste of money. ordered from simrad per jethro around 155 for parts. send me a pm with a email and I will send you part nos

it will be eaiser to forward a email from jetro with links and instructions than to repost.

[Brianmoore25]

May not be overheating. Check the sensors for proper operation.

[munchie]

May not be overheating. Check the sensors for proper operation.

lol. chewing mud and or grass, pretty sure when it overheats

[Natch64]

Munchie,
I'm going to add a water temp gage for my 250SHO as well. The Yamaha gages don't have numbers, so I'm curious as your choice.
Thanks

[munchie]

I am using the yamaha gauge. it doesnt show numbers but the needle does move easily. also have the lowrance display showing numbers that once engine warms up, they never change. this is a standalone dash gauge.
2 1/4 inch hole I think

[Natch64]

Thanks.
Merry Christmas

[H2Power]

Good thread here guys … it is odd that Yamaha sends an NMEA 2000 signal from a sensor in the block when it appears the head temperature is more sensitive and thus probably a more useful area of the engine to monitor.

Munchie sent me the part list, so I am posting it here for others to access too. I’m also posting a picture of the gage with wires. I’ll take a GUESS at the wiring, but have not installed this so don’t know. Hopefully Jethro or someone else with experience can confirm or correct.

My GUESS on the wiring:
Sensor plugs into 4 wire harness: Sky blue to sky blue, black to black.

4 wire harness yellow to ignition power, black to ground.

2 wire harness blue to ignition power, black to ground (I'm guessing this is for gage lighting?)


6Y7-83590-10-00 http://www.simyamaha.com/Yamaha_Wate...3590-00-00.htm

688-83591-00-00 http://www.simyamaha.com/Yamaha_Wate...3591-00-00.htm

6CB-1241B-01-00 http://www.simyamaha.com/product_p/6cb-1241b-01-00.htm

[jethro1]

Here is the wiring shown graphically.

[H2Power]

Thank you Jethro!