The Stovebolt Site Forums The Shop Area Engine Shop 250 chevy engine operating temp

What is the correct operating temperature for a 250 chevy engine in a 1948 3/4 ton truck at 45 mph, i have a 180 thermostat and the truck runs well but on hot days when the outside temp is 90 to 100 the truck will run at 200 but does not reach 210

at what temp would you be concerned and would you switch to a desert or heavier radiator, if so would you need to use the short water pump. thanks

As long as it doesn't boil over you're probably fine. And how accurate is your temp ga anyway? Also just run minimal coolant vs 50-50, will cool better. I have an electric fan in front as a backup on the hot days in traffic, plus an overflow container.

"Operating range of 160º to 210º F."

"On a carburetor-equipped engine, often a 180º thermostat is used, although a little hotter thermostat rating (190º-195º) may make the motor more responsive and add a little fuel mileage. It may also help to burn off some of the by-products of combustion, such as moisture and acids which form and get into the oil."

The above can be found in this very informative article related to Bulletproof Cooling System

I have an "off topic" 5.0 HO motor in my '27 roadster pickup hot rod that runs about 195-200 F. consistently. I thought that was too hot, did some research & found the above article.

The article is consistent with other technical articles I have read that conclude that keeping the engine cool (in the lower part of the 160 to 210 range) is not a good thing. So the temperature you are describing at the upper end of the 160 to 210 range should be good for your 250 cu in. engine.

Also, be careful about running less than a 50/50 mix of antifreeze. When the concentration of antifreeze gets to low severe corrosion can occur. This is especially important if there are any aluminum components in contact with the coolant.

Hope this helps.

John

Mine ran hot till I moved the sending unit to the thermostat housing. Now it stays right the thermostat temp. which is 190.

If the sender is in the head between #1 and #2 cylinders, it will read high. 200 is OK as long as you are not loosing coolant. Add a small overflow just to see if or how much you may be leaking.

FYI, I am using a aliminum radiator from Afco in my truck. The stock one did the job ok, I just got tired of fixing the tank seems. The aliminum was almost a bolt in other then rerouting the lower hose and moving the brackets for my application.

Joe

thanks to all for the good advice. I will add an overflow and will read John's article

Thanks John for sharing the article about cooling systems...very informative.

Operating at or above an actual coolant temperature of 200 degrees, even intermittently, is going to require a pressure cap to prevent periodic coolant losses due to boiling over at times. The sticking point is how much pressure the radiator and heater cores are able to tolerate without rupturing. The boiling point rises 3 degrees for every pound of pressure, so a 7 pound cap will raise the boil-over temp 21 degrees- - - -to 233. Modern aluminum or tube=type copper radiators can handle 14-17 PSI without a problem, but the "honeycomb" heater core might not live at that sort of pressure.

A 180 thermostat maintains a low enough minimum temperature for a 0,4,or 7 pound cap to handle momentary spikes in temperature. Going hotter than 180 with the thermostat temp requires a higher-rated pressure cap. If a system with a 180 thermostat is getting to 200 degrees or more routinely, there's not enough radiator to do the job, or it's dirty.
Jerry