[C320-list] Engine water temp problem

[Rick Sulewski]

Graeme,
If you did anything with your wiring over layup you could have a sensor lead  grounding and pegging your gauge. For example, several years ago I had my valve cover off to adjust my Westerbeke valves and inadvertently pinched the temp sensor lead when the cover was reinstalled and that caused my temp gauge to peg.
Rick

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Onat Dogruer
Sent: Friday, April 07, 2017 11:17 AM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Engine water temp problem

On a side note, I just replaced the 18 year-old Johnson water pump (with same model Johnson pump) on our Yanmar and the temperature is not going above 160. It used to hover around 170F. I wonder if they improved somehow the efficiency. 
-OnatKittiwake #546, 1998

      From: Allan S Field <allan.field at verizon.net>
 To: C320-List at Catalina320.com
 Sent: Thursday, April 6, 2017 2:20 PM
 Subject: Re: [C320-list] Engine water temp problem
   
Our boat was about 10 years old when the temp sender unit failed.  A replacement was ordered from Yanmar for about $20 US 7 years ago and installed in about 10 minutes.  Problem fixed.

Allan S. Field
Sea Shadow - C387, #103
Columbia, MD

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf Of Graeme Clark
Sent: Thursday, April 6, 2017 1:14 PM
To: C320-List at Catalina320.com
Subject: [C320-list] Engine water temp problem

First time I run the engine this year the water temp gauge goes off the clock!
I therefore bought a point and shoot laser thermometer and sure enough the engine temp ( measured where the sensor is and also at fuel injector points) is around 170f whereas gauge is showing 280-290f

So it's the sensor or the gauge. How do I test the sensor.  There is only a single terminal so I'm guessing the resistance changes with temp. Does anyone know what resistance should be at say, 170f ?

Or is there a simple way to test gauge

I did have the instrument panel out this winter to repair the lid so it could be a dodgy connection I guess. I'll check everything again but any more info would be handy as I'm stuck on boat with limited internet access!

Graeme
#366, 1996 running Yanmar 3GM30F


Sent from mobile: please excuse typos etc.!