Hello gang... Grant here. My 59 w/stock 235 and factory gauges does the same thing. Rarely will it work correctly, but often pegs hot... nope, it doesn't even burp an ounce of coolant, so it is definitely not hot. A professional repair shop in MN tested gauge unit, it's good. I tested wires for continuity, all good. I replaced the sender, and the replacement came with sealant on threads... could this be causing my irratic problem? Sounds like the same story as Hot Rod. let me know what you think??? Grant.
