radiator vs thermostat

[div4scpro]

I have 97 K1500 w/ 5.7L. I replaced the stock radiator w a HD one 2 years ago, replaced the thermostat w stock 195. I think now that was a mistake. With a heavier duty, more rows, radiator, what is the correct thermostat to use. don't have any overheating problems but the temp gauge shows quite a bit of fluctuation between 1st quarter mark and straight up, but never beyond. A digital monitor shows fairly normal warm up to an indicated 172 to 193, usually hovering around 188. am getting ready to flush system and change out thermostat and hoses for preventitive maint. any suggestions or similiar experiences.

[vncj96]

I would go with a 180 degree

[Dr_Zero]

Sounds like a wonky thermostat I have the same basic setup with a 180 stat and it stays right under on the first line idling on pavement in the florida heat.

Check out Rockauto they have a stant for less than $2

Here are the part numbers as most parts places cant get past what the computer tells them is the one you want or need.

Stant part #
13009 195 degree
13008 180 degree
13006 160 degree

[JCC]

The size of the radiator should not affect the engine operating temperature unless it (the radiator) is too small. A good 195 degree thermostat should cause the engine coolant temperature at or near the top of the engine to stay at about 195. GM designed the engine to run at 195, and you will obtain the lowest emissions, the least sludge buildup, and the best operation at that temperature.
The major reason to run a lower temperature thermostat is to get a slightly richer fuel/air mixture into the engine. At flat-out full throttle, the engine might develop a hair more horsepower - although I doubt that you would notice it on the street. The lower temp. thermostat will cause the engine to not quite reach it's designed operating clearances - although this would be a very minor issue. The other reason for a lower temperature thermostat is a cooling system or lean air/fuel mixture problem that is causing overheating. If this is the case, the problem should be addressed. The 180 degree thermostat is treating the symptom, not the disease.

[Jimmiee]

X2 - I see a lot of people here recommend 180 degree thermostats saying they increase performance. This is a very good explanation of why the above statement, pertaining to a street vehicle, is a myth.

[Dr_Zero]

I didnt go with a 180 for performance I did it so the system would run a little cooler, in traffic in the summer heat the extreme duty fan and the lower stat helped alot.

First was the flush, then the new fan with a 195 stat and it didnt open till close to 200~210 and I didnt want the engine getting that hot switched to the 180 and it may get a little warm but it doesnt go up to 200.

Also my truck is older truck the newer trucks might have issues mine has not other than in the winter the truck does not roast you like my wife likes it LOL