With or without a thermostat?

1

123finboy

Member
Will an engine run cooler without its thermostat? Some say yes because removing the thermostat eliminates any restriction, thus increasing coolant flow through the radiator. Others say it will run hotter because of the lack of restriction. They believe that even when the thermostat is wide open, there is still some restriction, which slows the flow through the radiator thus giving the coolant more time to dissipate heat.

I have a 180 degree in there now, and am thinking about going to a 160, but maybe I should remove it entirely to get a cooler run here in the swamp that is south Texas. What do you think?
 
My 2 bits... A thermostat is there to keep the motor running warm when it would get too cold, and does nothing one way or the other to keep the motor warm when it is getting hot. There is minimal restriction when the thermostat is open.
 
actually the restriction slows the flow allowing the rad to cool the coolant.5/8 worked for our race cars.or cut the teepee part off remove spring etc.I usually drill a couple of 3/16 holes in the outer edge when installing a new thermostat so if it sticks shut it will allow some coolant to pass.
 
Depending on which engine you have, there are some high flow stats. For our y blocks, it's listed as a mopar part I think. A search will turn it up. How hot are you running, at what ambient and speed? Or is stopped and at idle the problem?
 
54vicky: I've heard that too about the importance of restriction for cooling. I've heard stories of old school racers pulling out the thermostat and installing a washer to get the restriction back.
miker98038:
The engine I'm running is a 352FE with a 4bbl. My biggest problem is running hot when stuck in traffic or at a stop light. Do any of you know, what should be the temperature difference between the inlet and outlet on the radiator when it's fully warmed up?
 
You can find a lot of opinions on what the temp drop should be. 20 degrees seems to be a common opinion.

Do you have a fan shroud? Does it fit well, and sealed to the radiator. If you cool when moving, it's typically a airflow problem, either a missing shroud, wrong fan, or wrong spacer. Most fans need to be 1/2 to 1/3 outside the shroud for the combo to be effective. I don't understand the dynamics, but you apparently need to spill the air outside the shroud. If someone can explain this properly, I'd like to know.

The other common problem is air flow out from under the hood. Typical example, early 'birds need the hood popped open to cool in a parade. If you've got an FE in a hot rod with a full hood, headers, etc., this could contribute.

Some models have lower hoses with a spring in them to stop it from collapsing, and it rusts out, but that's usually a driving problem, not an idle problem.

If the engine isn't boiling out coolant, at 50% mix, it's really not a concern, up to 210 degrees, even more. Assuming the system has a pressure cap and nothing fails.
 
See how far you go back...

Remember those old steel Zerex anti-freeze cans? Those knock outs under the cap are the exact size of a thermostat. All you had to do was experiment with the hole you put into it and come up with an optimal flow.

Most FE Fords I had, I took the 'stat out in the spring and put it back in once fall came around.
 
If it ain't losing water it ain't over heating.....proper mix, good fan, good cap, all should be well. Never had an FE run hot when all the above was as it should be. My 62 Bird would go for hours in a parade with no increase, the 65 Bird has been in one parade (20 min) in 100+ temp and no issues. Both were .030 over engines, both had fresh anti-freeze, both had freshly rodded radiators and new hoses and both were/are factory air cars with shrouds.
 
123finboy you may want to look at using a 6 blade 17 inch fan if it will fit.not a flex fan as I have seen some serious problems when they break a fin off.the bigger fan will increase air flow.you can get them from speed shops summit etc.you could change pulleys but you may need smaller on water pump to speed up pump then you may need bigger to slow pump but this entails money when you factor in belts etc.as others have said proper rad cap coolant etc.also you could when and if you order fan also get the flow restriction kit it should come with a few different sizes if you are careful with gasket you should be able to solve your problem.if you want order a couple of gaskets. good luck. Barry
 
The only function of a thermostat is to maintain an even temp, ideally 180 prior to the 1980's, 190/95 on modern engines.
The practice of removing/replacing thermostats in the spring/fall was based on the alcohol based anti-freeze that was the norm in the 1930's/40's, alcohol boils at 180 degrees.. Modern coolant boils at about 230, boiling point raises 3 degrees for every pound of pressure on the cap.
Engines and their cooling systems are designed to run at a designed temp range, if an engine is running higher than normal, there is something wrong within the system.
Sometimes the problem can be as simple as a malfunctioning heat riser in the exhaust manifold, usually the problem is a plugged up radiator core..
 
You have to ask yourself if you are using it as a daily driver. A thermostat restricts flow until the engine reaches operating temp. By not running one, you will have a lot more wait for your engine to reach operating temp. Excess fuel consumption, poorly operating heater, sluggish running engine, excess buildup of moisture and related sludge, etc.

Run a thermostat of the proper temp unless it's a race car.
 
Diavolo said:
You have to ask yourself if you are using it as a daily driver. A thermostat restricts flow until the engine reaches operating temp. By not running one, you will have a lot more wait for your engine to reach operating temp. Excess fuel consumption, poorly operating heater, sluggish running engine, excess buildup of moisture and related sludge, etc.

Run a thermostat of the proper temp unless it's a race car.
Click to expand...

The above statement hits the nail on the head..
An engine that runs well and has good longevity, requires a proper thermostat..
 
Its is quite simple, if you have found you have to remove a thermostat there is something wrong with your cooling system [or you have a modified car ..prepare to chase your tail] car companies don't install them in every car for no reason.
 
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