Hello, was able to take my panel out for another run today, the temperatures are quite a bit cooler now, in the 40*'s F(5-8*C) and the engine coolant temps which should be at 100*C is barely reaching 70*C. Not sure what to check, I'm running a 195* thermostat in a 5.7liter sbc, headers and 2 1/2" dual exhaust, it has the original stile radiator 4 row core that I bought from Midfifty. Any suggestions??

 

Stuck thermostat ??? With engine cold remove radiator cap, start motor and see if you have coolant flow when cold, shouldn't be flow till it gets to temp.. But as you know Im no mechanic, so others please chime in.

 

Try one of those infrared thermometers to verify your guage is correct. Good luck.

 

Pretty sure the gauge is accurate, temp starts to come up at slower speeds and at idle.

 

Perhaps when you purchased the thermostat you got a fail safe one that sticks open. Just a thought.

 

I'm running Vortec heads with a Vintage Air front runner with short water pump, the vortec requires a bypass so the thermostat has a bypass built into it which is only 3 tiny holes not much bigger than 1/8''.

 

Are you running an electric fan or standard?

 

Electric fan.

 

Your high/low fan switch is set correctly then I assume. On about 212 and off around 175 anyway perhaps a smaller fan in the winter months. Was the air warm from the heater if you had it on?

 

Fan is set up properly, lot more heat from the heater once we slowed down and drove around town when the engine temp came up. I'm wondering if that 4 row core rad has too much cooling effect.

 

It shouldn't. The extra cooling capacity only effects the water once it leaves the engine. The thermostat controls the temperature of the water in the block and heads, and that should be what is running through the heater.

A cold running engine is going to be the thermostat. It is either opening too cold, sticking open, or is being bypassed too much.

 

Most likely the thermostat or bypass, as suggested. Be aware also, that trucks with very large cooling systems run covers in front of the radiators to minimize air flow when they're running in very cold temperatures. It has been my experience that you really don't need any fan when the temperatures drop below the 50 deg F mark. Back when, I drove a '52 Mercury without a fan year round. Not much traffic back then where I was. Just had to "time my stops so as to not remain stopped very long.

 

Try putting a piece of cardboard in front of the radiator and taking it for a drive. That is what you will see commonly here when temps drop below freezing around here.

 

Yes John I would also try the cardboard first. Than drive it
a lot so as to make the thermo work. If a chunk of crud is
holding it open it may then work it's way out. This has
worked for me in the past. And on new engines that should
be clean with now chunks. Go figure. Maybe the stat is just
sticky from some coating put on at the place it was built.
But either way making it work by forcing the heat with cardboard
worked for me and saved changing it out.

Also Jim is right on as to how to check it.

 

Well hopefully this weather will hold out so I can take it for another spin, I have no plans on running it through the winter when our roads are covered in salt. Unfortunately I'm back to work for the next 7 days and will not likely get a chance to take it out until I'm off again. I'll do what has been suggested and thank all you fine gents for your help.