Engine: Temperature sending unit

[Boehm]

My 1964 Wagonaire has a 289 V8. The problem is the temp gauge spikes when it warms. The thermostat is ok. I'm thinking the sending unit is bad. I found one in the SI parts book, but were did they hide the sending unit.
Thanks
Steve

[greyben]

In my limited experience the major cause of this problem with fuel and temp gauges lies at the indicator. These indicators must have a good ground. The ground is achieved by direct contact of the gauge to the instrument panel. A little corrosion or whatever will degrade this contact after 50 years or so. Sometimes this can be fixed by simply loosening the indicator hold down nuts and moving the gauge around hopefully to establish a new ground contact. Be sure to resecure the nuts snugly. Oh yes! Before poking any tools behind the dash be sure to disconnect the battery or you'll be sorry. This from the shop manual and my limited personal experience.

[Stu Duglee]

The sending unit is on the drivers side...at the back of the head,getting a wrench on it is a challenge.My gauge was pegging last summer and after a few tests I determined it was the sender.I found an old wrench that had a vintage Ford logo on it & it just happend to have the correct bend & a deep closed wrench end that fit perfectly on the sender & with the right bend it didn't interfere with anything while I was tuning it loose.