Yanmar 3YM30 temp gauge readings way off

Jaychale

Recruit
Joined
Jul 12, 2021
Messages
3
I've got two temperature gauges (was trying to prove that the first one was just wrong) wired into the sender in the coolant system, and both read wildly wrong, and not even by the same amounts.
Thought that was odd, so we swapped in a second sending unit, and got pretty much the same readings. We were confirming the temp with a temp gun and it never got above 80C

We did keep some data points comparing the values at a given time until it became clear that both gauges were just wildly off. I'm sure I could find that if it was important.

These really aren't complicated gauges to wire, Ignition, sender and ground, so if I'd wired something backwards it should just not work at all.

The only thing I can think of is the wires themselves? All we had was 14ga, but figured it should be fine even though the gauges asked for 18ga. Unless I just have two bad senders?

Any thoughts?
 

alldodge

Supreme Mariner
Joined
Mar 8, 2009
Messages
34,060
80C hope it was closed cool and not open
Was the temp reading taken at the thermostat housing?
 

alldodge

Supreme Mariner
Joined
Mar 8, 2009
Messages
34,060
Closed cool means it uses antifreeze and a heat exchanger. Open cool is no heat exchanger and its raw water cooled
 

alldodge

Supreme Mariner
Joined
Mar 8, 2009
Messages
34,060
ok thanks
The wiring should be of no issue so long as they have good connections. The gauges draw very little current and 18ga is enough and 14ga is even better. Assuming your gauges are the north American standard (240 ohm cold to 33 ohms hot) you can place the sender on the stove and heat the water up watching the temp and resistance values

Can also ground the sender wire and the gauge should peg hot
 
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