Keeping the engine cool
The thermostat has two valves:
a. one valve opens/closes the the inlet path from the radiator;
b. the other valve closes/opens the engine block recirculation back into the pump (i.e. bypassing the radiator);
these two valves work in the opposite mode of each other (i.e. one opens as the other closes, and vice-versa)...
when the TS is removed, both passages a. and b. are open, so the pump draws cold coolant from radiator and hot coolant from engine block, at the same time...
BUT: the radiator has higher flow resistance than the engine block, so the pump tends to pull more coolant from engine block than it does from radiator, this leads to running hot.
a. one valve opens/closes the the inlet path from the radiator;
b. the other valve closes/opens the engine block recirculation back into the pump (i.e. bypassing the radiator);
these two valves work in the opposite mode of each other (i.e. one opens as the other closes, and vice-versa)...
when the TS is removed, both passages a. and b. are open, so the pump draws cold coolant from radiator and hot coolant from engine block, at the same time...
BUT: the radiator has higher flow resistance than the engine block, so the pump tends to pull more coolant from engine block than it does from radiator, this leads to running hot.
****. I was picturing a single function stat and not the dual. I recommended pulling it as a testing step. I guess you'd have to remove only A portion or drill it to test the system the way I was picturing it.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
If you want to run without TS, you have to block the recirculation/bypass passage.
On The Tree
Joined: Sep 2016
Posts: 103
Likes: 18
Thermostats regulate minimum temperature, cooling systems regulate maximum temperature. A blanket statement such as "engines are supposed to run at blah blah blah temp" are pointless. An engine should run at the temp it's designed for. It will usually always make a tad more power and torque running cooler, around 160-180. Oem engines are built and designed to run at such high operating temps for emission purposes only. With such a variation in temps across the entire country, it's difficult for a single tune to be efficient in all areas..........so they design the engine and tune to the highest temp possible, to cover all areas. There's nothing wrong with the temps that you're seeing. If you want it to run cooler, start working your way through your cooling system. Once you get the temp where you want it, revisit your tune. Even adding a bit more fuel may be enough to bring the temps down.
Thermostats regulate minimum temperature, cooling systems regulate maximum temperature. A blanket statement such as "engines are supposed to run at blah blah blah temp" are pointless. An engine should run at the temp it's designed for. It will usually always make a tad more power and torque running cooler, around 160-180. Oem engines are built and designed to run at such high operating temps for emission purposes only. With such a variation in temps across the entire country, it's difficult for a single tune to be efficient in all areas..........so they design the engine and tune to the highest temp possible, to cover all areas. There's nothing wrong with the temps that you're seeing. If you want it to run cooler, start working your way through your cooling system. Once you get the temp where you want it, revisit your tune. Even adding a bit more fuel may be enough to bring the temps down.
