Water Temp Gauge stops working after 10-15 Min of Run Time

[PartsChaser]

Hey guys, first time, long time.

I have an 87 Four Winns Horizon 170 with the 4.3 Merc, and I have what I hope to be a simple problem. I know the Water Temp gauge is good, as it will work for the first 10 minutes or so of use, then the gauge begins to waiver and drop to zero. Usually have to let the boat cool all the way down and re-start for it to work again (for a few minutes).

My question is that would it be a ground issue if it works initially, then fails? or is there something in the harness that may be having issues once the engine is up to temp?

Thanks in advance!

 

[Silvertip]

Re: Water Temp Gauge stops working after 10-15 Min of Run Time

It may be the temp sensor on the engine. Even though the gauge works initially, the gauge itself may quit working after awhile. I'm leaning toward the sensor however since the engine needs to warm up before the failure occurs. What you need to do is disconnect the wires from the sensor and measure its resistance. When the gauge fails measure the resistance again. I'm guessing, but I think you will find it measures open circuit (infinity).

 

[PartsChaser]

Re: Water Temp Gauge stops working after 10-15 Min of Run Time

thanks, will check that out for sure!