The Stovebolt Site Forums The Shop Area Engine Shop Thermostat Question

I know this has been discussed before, but I could not find the thread. I want my 1954 235 engine to run cooler. It now has a 180 thermostat. If I change to a 160, will it actually run cooler in normal driving conditions, or will it just be quicker to open? Thanks.

a thermostat sets the minimum temp the coolant can be, the condition of the cooling system and tune of the engine determines the maximum, which should be at least 160 and ideally 175-190 .... what temp is it 'normalizing' at now? actual temp, measured preferably with a good laser thermometer, not by the gauge, which will not be very accurate

Bill

Thanks, Bill. OK, so let me ask - if the engine is "capable" of running at 160, and I want it to run at 160, then if I put a 160 unit in, it should be able to maintain that temp?

I think the original thermostat was rated at 160 degrees. The information at that link indicates that it stsrted opening at between 148-156 degrees and was fully opened at 176 degrees.

See if you can find the specs for your thermostat, you might be surprised when you see what the temperature is when it is fully opened.

why do you seek to make it run colder? if you're having overheating problems, the thermostat is not the fix - if all is good, it should stay about 160 with a 160 stat, but as Tim points out, there is a range of temp they operate at, it isn't a "snap open/stay open" situation .... and as I said, the exact temp it runs at depends on the condition of everything, I've always found the 235's to run colder than is healthy for them if you let'em, but the engine was designed to work best and last longest at temps above 160, otherwise they can sludge up faster, require more frequent tune-ups and use more gas

Bill

My 1954 vintage 235 (1950 3600) runs right at what Tim said 180 deg. I use a 160 thermostat because here it is not unusual to have days over 90+. I found with a 180 the truck ran close to 200 and was always leaving coolant on the ground. I also run a factory overflow tank and have had no issues since adding that and switching to the 160.

My manuals for 1.5 ton Chevvys is to run 160 stock and if a heater is installed use 180.

The gauge will bounce around but should stick right around the t-stat set point unless idling for a long time, going up a hill (high power output, low forward speed for cooling).

When you turn off the motor is most likely will shoot up to 200+ unless you idle for a few minutes to let the motor cool.

what temp is it running at, and what temp do you want it to run at? Is it overheating?

Thanks for all the comments. My concern was that with the 180 thermo, the oil pressure at idle was almost down on the peg, and the temp gauge is just below the midpoint. I'm guessing that's about 180 degrees give or take.

However, with the 160 installed and a hot engine, the temp gauge shows a definite drop in coolant temperature, and the idle oil pressure goes up to about 7-8 lb.

Also decided to do an oil change from straight 30W to a 15W 40, and the pressure went up a bit more - about 10.

So, I am satisfied, and I think the 160 will be fine. BTW, I see no difference whatsoever in engine performance regardless of the thermostat or oil viscosity. I think I just wanted some peace of mind. Thanks again!