Thermostat Myth

[Downey]

take it out on a 100 degree day and beat on it i know for a fact that it will over heat. or tow a heavy load up a long hill and i mean 3-4k. and a mile or 2 long hill it will over heat. i would never run with out a tstat. the coolant doesnt stay in the radiator long enough to get cooled off so you keep pumping hot water back into the block.

 

[GoodOld85BlueBalls]

Did you block the bypass when you took out the thermostat? That is the mistake most people make when removing it. Most people put in a blanking sleve and that is what stops this. If you dont plug it you will most likely overheat due to it keeps bypassing the radiator.

 

[Sevensecondsuv]

I forgot to put a thermostat in once when I was throwing the top end together in a frenzy after replacing the intake manifold gasket on my explorer. It was early summer so I just ran it like that until october when I decided I wanted heat. Then I put a thermostat in.

 

[feellnfroggy]

Did you block the bypass when you took out the thermostat? That is the mistake most people make when removing it. Most people put in a blanking sleve and that is what stops this. If you dont plug it you will most likely overheat due to it keeps bypassing the radiator.

I dont know about all cars, but all my fords you cant 'bypass' the radiator. The top rad hose routes from the top of the block straight into the rad. At the block where the hose clamps in is the thermo stat. Theres no other hoses for it to bypass the radiator, but like alot of people have said it will flow through the rad too fast and not allow the fluid to cool. Plus if it flows through the block too fast it will not draw enough of the heat out of the block.

As far as Im concerned its not an epa part. Ford didnt put the t-stat in there to satisfy emissions, and its not a compromise piece that you can do without, like the egr is. Ill keep my thermostats where they belong.



Now I will say this, there is a t-stat made that when it goes bad it blows in the open position, unlike factory t-stats that blow in the closed position. This will definitely save your motor in a bind.

 

[Tulsa Time]

the coolant doesnt stay in the radiator long enough to get cooled off

This never made since to me. The part that always gets left out of this statement is the coolant also spends less time in the engine absorbing heat. Therefore it does not need to dissipate as much heat while it is in the radiator.

I have been working on cars for 25 years, some professionally and some as a hobbyist. While I don't make it a habit of running without a t-stat, over the last 25 years I have done it on multiple occasions. Without exception, every engine ran cooler without a t-stat than with one.

 

[85_Ranger4x4]

I dont know about all cars, but all my fords you cant 'bypass' the radiator. The top rad hose routes from the top of the block straight into the rad. At the block where the hose clamps in is the thermo stat. Theres no other hoses for it to bypass the radiator, but like alot of people have said it will flow through the rad too fast and not allow the fluid to cool. Plus if it flows through the block too fast it will not draw enough of the heat out of the block.

My 2.8 has a bypass hose that runs from the backside of where the lower radiator hose meets the water pump to the thermostat housing.

BTW, that rear lower neck is a joy to get clean enough to seal... a truely stupid design.

I have been working on cars for 25 years, some professionally and some as a hobbyist. While I don't make it a habit of running without a t-stat, over the last 25 years I have done it on multiple occasions. Without exception, every engine ran cooler without a t-stat than with one.

If it can't absorb the engine heat... then it will read cool.

 

[Tulsa Time]

If it can't absorb the engine heat... then it will read cool.

This is because any given molecule of water is in contact with the engine for less time. However, any given molecule of the cooling surface of the engine is in constant contact with coolant that has absorbed less heat. In other words, the engine is still transferring the same heat to cooler coolant.

 

[GoodOld85BlueBalls]

I dont know about all cars, but all my fords you cant 'bypass' the radiator. The top rad hose routes from the top of the block straight into the rad. At the block where the hose clamps in is the thermo stat. Theres no other hoses for it to bypass the radiator, but like alot of people have said it will flow through the rad too fast and not allow the fluid to cool. Plus if it flows through the block too fast it will not draw enough of the heat out of the block.

As far as Im concerned its not an epa part. Ford didnt put the t-stat in there to satisfy emissions, and its not a compromise piece that you can do without, like the egr is. Ill keep my thermostats where they belong.



Now I will say this, there is a t-stat made that when it goes bad it blows in the open position, unlike factory t-stats that blow in the closed position. This will definitely save your motor in a bind.

Next time you have a thermostat out of any engine have a close look at the housing or where it goes into the block or housing. You will see that all of them have a bypass either external or built right into the top of the block or another passage. (cast right into the steel block) Thats how it works, it will bypass till it gets hot then open and mix hot and cold till it opens all the way and then gets full flow. If you had no bypass there would be no flow at all and it would no work with any efficiency. Some bypass right into the connections for the heater core and hoses, thats why it warms up so fast because it is only the flow from the block and not from the radiator till the thermostat opens. A thermostat is just a mixing valve to put it in a simpler wording. And I do agree that it is stopping all flow (to the radiator) till the engine warms up, it is just going round and round iside the block through the "bypass", be it a hose or a cast passage or the heater system.......

And I will add this. A thermostat is partly an emissions controll device by keeping the temperature up in an engine it will not maks so many formaldehydes. If you don't belive me look it up. A cold running combustion process will also make a lot more unburned hydrocarbons.

 

[JimJa1943]

Not mentioned here is when operating w/out a thermostat you will not get your vehicle out of the "cold-cycle loop." The ECU thinks the engine is not warmed up and will keep the mixture rich.

Ford originally installed Bosch t-stats in their Rangers and Explorers w/the 4L engine (can't speak to the other engines). Over time this thermostat will slowly remain open, preventing the engine from completely warming up. It happened so gradual on my '92 Explorer I didn't even notice it until really needing the heater, which didn't seem to be working as well as I remembered from several years prior. My fuel economy was also 2-3 MPG less than when last computed. New thermostat and all returned to normal.

If your gauge is in the lower 1/4 of the "band" you may have this problem.

BTW, the auto mfgrs spend millions trying to get the most from their engines. Running w/out a t-stat is trying to defeat this R&D. If all is well with your engine, a thermostat won't overheat the engine.

Just don't think is wise to run w/out one - all things being equal.

 

[85_Ranger4x4]

And I will add this. A thermostat is partly an emissions controll device by keeping the temperature up in an engine it will not maks so many formaldehydes. If you don't belive me look it up. A cold running combustion process will also make a lot more unburned hydrocarbons.

Not really a "emission control device"... they were in use well before anyone cared about emissions.

 

[kimcrwbr1]

In death valley where it gets 120 in the shade we used to put a large washer with a oversize hole in the center to restrict the water enough to cool it in the radiator but in the cold mornings you had to go without heat. The computers are designed to run at operating temp for the best effeciency when you change the operating temp of the engine the computer might just say f u after a bit plus the berings will be out of tolerance for proper oil flow.

 

[GoodOld85BlueBalls]

Not really a "emission control device"... they were in use well before anyone cared about emissions.

Yes. Really it is an emissions control device. They just didn't realize it when nobody cared, but they were doing good. By letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions.

 

[97RangerXLT]

Not mentioned here is when operating w/out a thermostat you will not get your vehicle out of the "cold-cycle loop." The ECU thinks the engine is not warmed up and will keep the mixture rich.

Ford originally installed Bosch t-stats in their Rangers and Explorers w/the 4L engine (can't speak to the other engines). Over time this thermostat will slowly remain open, preventing the engine from completely warming up. It happened so gradual on my '92 Explorer I didn't even notice it until really needing the heater, which didn't seem to be working as well as I remembered from several years prior. My fuel economy was also 2-3 MPG less than when last computed. New thermostat and all returned to normal.

If your gauge is in the lower 1/4 of the "band" you may have this problem.

BTW, the auto mfgrs spend millions trying to get the most from their engines. Running w/out a t-stat is trying to defeat this R&D. If all is well with your engine, a thermostat won't overheat the engine.

Just don't think is wise to run w/out one - all things being equal.

In death valley where it gets 120 in the shade we used to put a large washer with a oversize hole in the center to restrict the water enough to cool it in the radiator but in the cold mornings you had to go without heat. The computers are designed to run at operating temp for the best effeciency when you change the operating temp of the engine the computer might just say f u after a bit plus the berings will be out of tolerance for proper oil flow.

yep. the thermostat meters the coolant to the radiator. this allows the engine to run at operating temperature which makes it run more efficiently. The computer monitors the engine temp via sensors and if it detects it running cool, it will keep the fuel mixture rich until it warms up. (thus giving you poorer gas mileage) So while it was not designed as a emissions control device, it is integrated into the emissions of all modern vehicles through the pcm.

AJ

 

[feellnfroggy]

Next time you have a thermostat out of any engine have a close look at the housing or where it goes into the block or housing. You will see that all of them have a bypass either external or built right into the top of the block or another passage. (cast right into the steel block) Thats how it works, it will bypass till it gets hot then open and mix hot and cold till it opens all the way and then gets full flow. If you had no bypass there would be no flow at all and it would no work with any efficiency. Some bypass right into the connections for the heater core and hoses, thats why it warms up so fast because it is only the flow from the block and not from the radiator till the thermostat opens. A thermostat is just a mixing valve to put it in a simpler wording. And I do agree that it is stopping all flow (to the radiator) till the engine warms up, it is just going round and round iside the block through the "bypass", be it a hose or a cast passage or the heater system.......

And I will add this. A thermostat is partly an emissions controll device by keeping the temperature up in an engine it will not maks so many formaldehydes. If you don't belive me look it up. A cold running combustion process will also make a lot more unburned hydrocarbons.

This I didnt realize about hte bypass, I just figured the water stayed in the block while absorbing heat then at the appropriate temp the tstat was pressure opened like the rad cap and allowed to flow into the rad, while that was happening the cool water was flowing into the block, and it cycled like this a bazillion times. Didnt know the fluid actually kept moving.

 

[Mac]

The best reason to always run a thermostat is because of the wear. Got this chart out of the How to Rebuild a SBF. They've been running thermostats long before computers.
Dave