318 temp gauges

[fpawn]

Notice that temp gauges on one of the engines will shut down and than come back on in a while. Gauges shut down on both stations so I am assuming it might be a ground wire. What is best way to track problem? Is wiring for temp gauges on thermostat housing? Ant help is appreciated

[The Dog House]

The temperature sender is on the front of the engine underneath the thermostat housing. You can see the OEM sender (brass colored object sticking out of blue engine block) below the hose where I installed a new sender (see below). The temperature gauge wire will be attached to the end of that.