Gauge Reads Hot, Rad Temp OK???

[3yearcuda]

I just fired up my 440 for the first time since the rebuild. Break in went great but the dash gauge in my 69 Barracuda slowly climbs to 3/4, so showing very hot. I stuck a thermometer in the rad and coolent looks to be circulating at around 170-175 with 180 thermostat. During the build I put in a new temp sending switch (small brass one) into the front of the water pump. I was thinking that the sending switch was telling me the engine is hot but the rad is cooler meaning the thermostat wasnt working properly. When I run the engine up to where I dont feel comfortable with the gauge reading hot, I shut it down. The block doesnt sound like its as hot as the gauge looks. I'm stumped.......anybody got any ideas?? Thanks for your help.

 

[1968FormulaS340]

My guess is that 3/4 on the 40 year old factory gauge is 180 degrees.

In other words…… Everything may be fine. Verify the temp with a mechanical gauge.

 

[beawulf]

I had the same trouble and used the sender unit from my 318 as it matched the gauge and have no problem now it seems that the resistance is wrong for the gauge with some of the after market senders , I also use a capilary type temp gauge in the top hose of the rad " just in case " to check on the dash one when the temp in the mec gauge reads 180f the dash one is about halfway so you need to use the origional sender unit hope this helps