***water temp gauge***

[catfish123]

I hope that the information I am going to provide here will help someone in the future. Background information is:

280 Mercury ROS
Old gauge was a Faria
New gauge is a Livorsi

I have the stock water (head) temp sending unit from Mercury that includes 4 wires off it so that it is not only sending information to the gauge but it also "feeds" the overheat alarm.

For the record, this sending unit IS NOT a water temp sender from Mercury, but a black head temperature sending unit that fits into a cylindrical hole in the starboard side of the motor. 280 HP motors are not "equipped" with a threaded hole up higher where a true water temperature sending unit can be used.

With the Faria gauge, My idle temps were barely enough to get the gauge off the 100 degree mark. In fact, on a lazer infrared sensor, the outside temp head readings were around 90 degrees. Up and running, the Faria gauge would go to 130-140 maximum.

Although I have read various places that many guys with 280's are running at 160-180 degrees, the person I rely most heavily on for accurate information told me that is too hot and that the 130-140 is the correct running temperature.

Now that I have a Livorsi water temp gauge, being fed by my stock Mercury "head" temperature sender, the gauge reads 125 degrees at idle and it goes to 170 or so when up and running. At first, I was concerned that my motor was now overheating but that is not the case. Apparently the ohm resistance level of the Faria gauge, and from what I'm told, most other temp gauges as well, is different than that of the Livorsi gauge.

A lazer infrared heat sensor gun has proven that my motor IS NOT getting to the temperatures the Livorsi gauge indicates. At this point, I think my choices are to either forget it if I want to keep the new, matching Livorsi gauge to the rest of my new Livorsi gauges, and accept that the reading is 30-40 degrees too high--------------or to go back to my old gauge or one that reads correctly with the Mercury sending unit.

I have found over the years that when I post my "problems" here and elsewhere, that I feel a lot of the time I'm the only one who has ever had the problem I'm posting about.

I'm sure for some the answer would be to use the Livorsi sender, but again, it is threaded and is not intended to go into the "head" temperature reading hole provide on the head by Mercury.

Sorry for rambling, but hopefully if anyone else ever has this problem, they may find this thread and avoid everything I've gone through trying to figure this out and worrying about it.

 

[patches]

I'd drill and tap a hole in the head that goes into the water passage and use the Livorsi sender.

 

[h2oskiier30]

The Livorsi sender can be made to work with very little effort. I had to do the same with my AutoMeter gauge...it requires an AutoMeter sender due to the difference in ohm output. I really like the idea of getting a correct reading. Here's a pic of mine....

 

[Myron]

I have Autometer, one temp gauge for each bank, I read water temp not cylinder head temp, the senders are in the top of each head. I rely on this more than water pressure, with the senders at the top the second no water is there the temp goes up, my motor reads 30 degress hotter than the lake water, has worked for years. Most gauges need to be match to there own sender to work properly.

 

[SLOmofo]

I'd drill and tap a hole in the head that goes into the water passage and use the Livorsi sender.

True Dat!

Or you could find a RacePac III guage and put an pyro through the head into the water jacket. Almost instant reading.
A head temp guage is history, it takes a long time to transfer heat from the water through the metal of the head and then into the metal of the sender. Then there is the time for the resistance unit to pass voltage and then the time for the guage to react.
My RacePak guage saved my motor from sure death because of it's fast reacting and BRIGHT LED warning light. I had just launched the boat and was warming it up, traveled at low speed about a half mile when the light started flashing. Sucked a Frito's bag over the lower units water pick up.

 

[suicidealli]

I'd drill and tap a hole in the head that goes into the water passage and use the Livorsi sender.

Me too.....

 

[Bobalouie]

Why not just put a fitting into the hose that comes out of the bottom of the block where the poppit would be on other motors? That water should be the hottest in the block and putting a T fitting in there that would accept the sender seems like an easy way to get water temp readings. Or, am I out in left field here?

 

[tomoad]

with the sender in how do you hook up the overheat alarm etc? a 280 sender is on the starboard with wires running to who knows where. How would you configure that with a stock 280 electronics

 

[h2oskiier30]

Put it in the port head, tomoad...just like in my pic above. That engine pictured above is a 280 block, it just doesn't appear to be that way because of the gasketed heads. I had Ruck slot the bolt holes on that set of head so they'd work on a 280. The sender wire plugs right into the tan wire coming out of your key switch harness there where it plugs into the engine harness.