resdoggie

The ts does set the operating temperature as in any other system designed to remove heat using a heat exchanger. Otherwise, how do you regulate the coolant flow to maintain a constant temperature within a minimal range of a few degrees?

The ts gradually begins to open prior to reaching its designed rating of say 180* At 180*, the ts is fully open allowing coolant at 180* to enter into the rad. The rad cools the coolant and it re-enters the engine to get re-heated to 180* controlled by the ts's throttling action. If the engine can't heat the coolant to 180*, the ts will not open, such as when the coolant is cold on startup. A properly sized and functioning cooling system will maintain the temperature at 180* regardless of outside air temp. If the coolant temperature cannot be maintained at 180* and rises above that, then the radiator is most likely not designed to handle the cooling requirements in the ambient conditions. Now throw in an A/C system with a condenser in front of the radiator. This will put an additional tax on the radiator and can cause the coolant temperature to rise entering the engine. The GM engineer's only have so much room to work with sizing a radiator and selecting an acceptable material to build them so there is a trade-off in cars running warmer with A/C systems in general but maybe not so much these days e.g. better designs, materials. I don't know GM's design criteria for radiators but I'll guess it's designed to function properly in ambient air temperatures of -50*F - 120*F which would cover about 99% of all expected operating environments. Now, you could take the ts out and the engine will find a normalized temperature but only at that ambient air temperature. As the ambient air temperature fluctuates, so will the coolant temperature. Also, ever see the big rigs with covers over their grilles in the winter? They do this to prevent cooling the coolant in order to maintain a proper coolant temperature in the engine. Remember, too cool an engine operating temp reduces the oil's lubricity leading to increased engine wear.

fishslayer143

well said ...and accurate too

7T1vette

resdoggie:

You have a general understanding of the cooling system, but what you are missing is that the thermostat is ONLY there to speed the engine's heating up to the temp of the stat. If you have over-engineered a cooling system (too large a radiator, etc), then the stat CAN set the systems temps and it will regulate open/close to keep it there.

But, by design intent, the stat...once it is fully open...is to stay in the open position (completely) and the SYSTEM will regulate its own temperature based on how much heat is generated (by engine) and lost (to the environment). If designed properly, that stabilized temp will not be much higher than the stat temp (maybe 200*-210*F in hot conditions).

If the stat were to ALWAYS regulate the system temps, the pivots on that chinzy stat would wear out in short order. No, it is SUPPOSED to stay open, once the engine has warmed.

Hammerhead Fred

The thermostat serves two functions:
1) speed up engine warm up to operating temperature
2) temperature regulation by continuously allowing/restricting coolant flow to keep the engine operating within its optimal heat range.

For the OP: it sounds like your thermostat is stuck in the open position.

7T1vette

The primary source of dumping heat from the engine is via the radiator. As coolant temps increase, the temperature drop as coolant passes through the radiator also increases, thus regulating/managing engine temperature. You can believe that the T-stat "controls" engine temperature...but it doesn't; it merely 'modifies' it.

If the T-stat did the 'controlling', how would it manage rejecting more heat once it was fully opened? [ie, hot summer day with air conditioning on HI and car idling] Obviously, it can't; the radiator/fan does that job.

fishslayer143

People sometimes think a T-Stat in an engine is like the one in there home which maintains a chosen temp.. it does not.. it merely aids in warm up and sets a minimum operating temp. It cannot "cool" a hot running engine just because you put in a 160* stat..

Hammerhead Fred

Thermostats don't cool anything - they regulate the flow of coolant based on temperature of the coolant to a desired operating range - nothing more.

Obviously, If the cooling system is incapable of reducing the coolant temperature below the thermostat design limits (due to poor design or malfunction (fan/belt/radiator/etc) then the thermostat is useless.

Based on the OPs description the motor is not reaching the desired operating temperature - the thermostat is likely stuck open.

resdoggie

Exactly. The ts is a simple thermostatic control valve. I designed heat exchangers for heating and cooling systems in college as one of the many requirements for my marine engineering design program and then 20 years as a marine engineer. So I think I have a bit more than a general knowledge of how heating/cooling systems function.

USAFVeteran

Have you installed a new t-stat yet?

gcusmano74

The thermostat will "set" the minimum operating temperature of the engine. The efficiency of the water pump and radiator will "set" the max temp. Don't overthink it. A 180 stat is a good choice for our 40 odd year old machinery. Install one and be happy.

lvmyvt76

there is a little more than just removing 2 bolts, the liquid is the worst part to drain and refill without an airpocket. IMO and the bolts can sieze and brake off causing more problems.

Rebelrob

One thing I learned that might be old news to many, is I did the stat on the stove in hot water experiment. The stats actually open up pretty slow when they reach their set temp. They don't just pop open fully allow maximum flow at the set temp. Can't remember the one I got from Pep Boys, but its us made, and it actually starts to open at 170 and is about fully open at 180. I recently pulled intake to replace gasket, was getting oil from sides. Thats another post. Anyway, ever since I put it back on, temp would get up to almost 190 on gauge before stat was opening fully. Before I pulled intake, I could watch the stat open on my temp gauge, it wold get up to about 183 or so and then it would drop to 179/180 and stay there as long as I was moving or fans were running.
Figured I got a airpocket in system. Tried different 180 stats all same results. Drilled 3- 1/8 " holes in a high flow stat and that solved the problem. Was always against doing that, but I could not get it to operate the same prior to pulling intake. Of course now its colder out. Temps stays steady at 178-180 at cruising speed. I have a L88 hood that is not sealed properly across the top, probably getting a lot of air flow over the rad.
Dewitts rad, with spall electric fans. AutoMeter Mechnical Water temp Gauge.

Rebelrob

Agreed. I syphon a few inches out the rad before removing stat housing to avoid a dripping mess. Its a PIA...

mikem350

And dont overtighten the bolts

USAFVeteran

Try using a wet/dry vacuum. You can remove as much as you need in under a minute.