Water Temp Gauge working on land, not in water.

My Bayliner 1997 1750's temp gauge seems to be working fine on the muffs on land but in the water it moves only slightly when I turn on the ignition (twitches). It has a Mercruiser 3.0L, alpha one. I can't seem to find an obvious reason why it would work on the muffs and not in the water. Water temp is cold (about 65) but seems the engine should warm up above 130?

Any help would be greatly appreciated! I am new at working on my own boat and learning, so if you can please add a location on the engine for the part in question, that would be awesome.

Thanks again!

Re: Water Temp Gauge working on land, not in water.

Welcome to iboats.
Have you own the boat long? What was done to it, Prev Owner? Is there a thermostat in it? Could be stuck open. One thing for sure it is not over heating. Feel the motor if hot.

mswanson8029 said:

but in the water it moves only slightly when I turn on the ignition (twitches).

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Don't understand. Is it running? Did you take it out for a run?
You need to elaborate more so the experts here can help you.

Re: Water Temp Gauge working on land, not in water.

My mistake! I apologize.

A few more details: I have had the boat out about 5 times so far this year and when I first took it out the water was colder and even at that time the boat made it up to the 140-150 degree range. I believe the thermostat is in there because it seems to work fine on land. I'd had it about 10 years, never replaced the thermostat as it worked reliably up until this point. The motor doesn't seem to be too hot while running, normal heat level.

Could it be the wiring? Possibility a wire loose? Also was reading on here about proper grounding, are there items to check for that?

I am likely wrong but I feel since it is sometimes works fine, the wiring would be the first thing to check.

Thanks!

Re: Water Temp Gauge working on land, not in water.

A few more details: I have had the boat out about 5 times so far this year and when I first took it out the water was colder and even at that time the boat made it up to the 140-150 degree range. I believe the thermostat is in there because it seems to work fine on land. I'd had it about 10 years, never replaced the thermostat as it worked reliably up until this point. The motor doesn't seem to be too hot while running, normal heat level.

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Ayuh,... So are ya sayin' the gauge no longer moves, at all, when goin' boatin',..??

Which of the 5 trips did the gauge quit workin',..?? Under what circumstances at the time,..??

Re: Water Temp Gauge working on land, not in water.

Bond-o said:

Ayuh,... So are ya sayin' the gauge no longer moves, at all, when goin' boatin',..??

Which of the 5 trips did the gauge quit workin',..?? Under what circumstances at the time,..??

Click to expand...

I don't know specifically which trip it stopped working. It does work when on land and connected to the muffs but just not when I get out on the water.

Re: Water Temp Gauge working on land, not in water.

You will not get the water flow with muffs that you will with the boat in the water. More pressure and more volume in the water.
Have you replaced the thermostat? it could be sticking open.