Temp gauge all over the place
 

Last night my wife and I took our 49 Tudor to a wedding. It was about an hour and a half each way. The flathead ran great, but on the way home I noticed the temp gauge was showing much hotter than it normally does. It was a cool night too, temps in the 40s. The gauge was on the H while I was going down the road, but if I came to a stop sign, is would abruptly drop to it's normal. Also, we were getting very little heat. Could it be the thermostats? Both? Heater core issue? This is the first time we used the heat this year, and did not use it on the way to the wedding. Thank you.

Re: Temp gauge all over the place
 

You may have more than one issue.

Is the valve for the heater open from the head?
How is the fluid level in the radiator?

Re: Temp gauge all over the place
 

If temp sensor connection goes open circuit anyplace, the gauge will go from normal indication to full hot. That can happen if there is a loose connection or the points within the sensor in the left head are getting intermittent. Check the connections. If that does not help, connect both wires on the left head sensor to the same terminal, thereby bypassing the possibly flakey sensor. If that fixes the problem, replace the left head sensor.

Re: Temp gauge all over the place
 

Thank you. To be honest, I have not checked the water in a little while, but when I checked the oil it was nice and clean, no milk. I think it is probably good, but I will check. As far as the valve, I will check that too. For the sensor, I was wondering if that might be the issue, because the car did not seem hot at all, and also because it came right down as it did.

Re: Temp gauge all over the place
 

Sounds like classic signs of being low on coolant. Check the easy stuff first.