MD2040 Volvo Penta temperature gauge miss reading

[landonshaw]

I am having trouble with my temp gauge. When I start the engine, cold, it registers totally hot. As soon as the tachometer comes on, it stops altogether. It is obviously not hot at all. The gauge will not register when ever the tach is working.

Originally it began to not register at all so I disconnected the sensor wire on the engine, cleaned it and reattached. Now it registers but shows as though it is overheating, even though it is just started. Water is circulating thru the engine with no issues.

Any ideas?
Thanks, Dave
Aloisius

[landonshaw]

I can find the high temperature switch, where is the high temperature sensor. The sensor sends the signal to the gauge.

[tkeithlu]

You found the water temperature sensor. Those sensors are pretty simple variable resistors supplying a variable ground to the gauge, which is really just a little voltmeter. Usually the wire from the sensor goes to the back of the gauge, with another wire from the gauge to ground. Full voltage comes from the ignition switch to the back of the gauge.

It sounds like the problem is at your ignition switch, where a bad connection is alternately sending nothing or everything to the gauge. But, if it is the sensor that is creating the problem, they are cheap and available at your local auto parts store. Take the old one in and ask for one that is similar.

[GordMay]

See ➥ https://www.cruisersforum.com/forums....html#post2597