VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc Is it ok to not use a thermostat?

Hi Guys, I tried to research this topic on the site as it is quite popular question over the years. However, I couldn't quite find a definitive answer to the questions I have for my 35 Master with a 207.

I want it to run as cool as possible (just something that I have always liked in any car I have owned as I have had a few boil over and spew, leak, etc). I have seen recommendations on a 160 thermostat as ideal, however, I am thinking the engine will still run at least 160 without a thermostat, especially in warm weather, but the thermostat can only provide some amount of restriction. So, that is why I am thinking no thermostat will provide the most efficient cooling possible. In other words, a 160 thermostat does not necessarily mean the engine temp will be 160, but running no thermostat will ensure the engine is running as cool as possible in it's current condition.

I am not interested in rebuilding the engine at this time or taking apart to clean water passages and such... just trying to enjoy what I have and trying to see if this idea about no thermostat has any merit.

[list]
[*]Will not using a thermostat make the engine run as cool as possible?
[*]Are there any concerns associated with not running a thermostat other than the engine will take longer to warm up and the heater will be less effective?
[*]Is there a temperature range once at full operating temp (ie. less than 160) where the engine will be less efficient or potentially damaged by running too cool?
[*]I saw mention of a hot engine eliminating condensation in the oil. Does it take a certain temperature to do this and if so, what is that minimum temperature?

thanks much for your thoughts! :)

--John

Very few of those cars will run under 160 Deg. in warm weather. Originally a 140 Deg. was consideed a summer thermostat but they have not neen available for years. .
The thermostat will not make the engine run hotter or cooler other than bringing it up to 160 Deg. as a minimum Temp.
Condensation inside of the engine is not a problem in the summer unless you continually run the engine for five minutes and shut it off.

Thanks for the feedback, Gene.

I agree with Gene.

The only thing is that I believe that a 160 degree thermostat is too cool for best lubrication. Also, without a thermostat it will take longer for your engine to warm up to whatever temperture it will run at eventually and during different driving conditions.

Best,

Charlie

When I was racing, we found that when we made a spacer the size of a thermostat with a 11/16 hole in it, the car ran the coolest. We experimented with many hole sizes.

Thanks for the feedback, fellas... I am running around 195 with the old time thermostat. I will do some experimenting and keep ya posted! :)
--John

Very interesting, chevy1937. What average temperature did the racing engines run, and at what average rpm?

Thanks, Dean

I have always been told that with no thermostat the water circulates to fast and doesn't have time to cool in the radiator.

I had hope that the myth of water circulating too fast would have been dashed many years ago. It just doesn't happen even in modern cooling systems.

In the case of an older style non computerized race engine it is possible to find a point where the thermal transfer is ideal as above with the restrictor. The big factor with a race engine is that it is operated the same predictable and reproducible way every, single time.

In the case of a street driven engine, it needs to adapt to a variety of conditions. When too cool it runs poor so you need a stat to provide faster warmup. Too hot is a problem so the stat opens. The stat is basically there to keep the temperature bouncing up and down somewhere in a middle range throughout a variety of driving conditions and outside temperatures.

It's an old wives tale that won't die about the coolant moving "too fast to cool". In fact the exact opposite is true and the faster the coolant moves, the greater the cooling system's efficiency.

For a good long read:
http://www.pirate4x4.com/tech/billavista/Cooling/

Chipper and JYD in the modern system with less tubes in the radiator the faster the coolant flows in each tube. With the older copper radiators there was a lot more tubes to take the flow rate therefore a lower flow rate per tube. A thermostat restricts the flow for quicker warm up but even when fully open it is a restriction as most water pumps are capable of a higher flow rate than a thermostat or most radiators.
A lot of early cars will operate normally without a thermostat as in most cases they were only a option.
Tony

I raced late models on asphalt. The small block dinod at 580 HP. With no fan it would run about 190. We tried to keep it under 8000.

Chipper and JD,

Back in the forties and fifitesit seems I remember talk about Ford V/8s running too cool owing to too open flow through the radiator.

I don't know wheather that is myth or not. I believe I've seen thermostats positioned in the top hoses but most just ran without a thermostat.

I do know that the period Ford radiators used flues with more volume capacity, it seemed, than other cars. Rodded a heap of them. Removal replacement of top and bottom tanks were much easier than GM cars.

Best.

Charlie

The most important point to remember is that we are talking about a cooling system. The thermostat is just one component.

Changing one piece may or may nor change the overall performance of the system. For example, if the cooling passages in the engine and head are partially blocked changing the temperature rating of the thermostat or eliminating it will probably not eliminate an overheating problem. A larger radiator will not make a difference if the current one has enough heat transfer capacity.

My preference is to run an engine at a higher safe operating temperature rather than lower. That is better for combustion and lubrication and actually helps heat transfer because the coolant is at an even higher temperature than the air flowing through the radiator.

Cooling systems, like engines, transmissions, etc. depend on numerous parts all operating properly to do the job they were designed to do.

I will stand by my original post.
In the last almost 50 years I and my regional members have toured around the US in hot weather, often over 100 degrees .
Cars were mainly 1934-1940 models. Thermostat or not all cars had the same results and some with 160 Deg thermostats and some with no thermostats. Yes, the engines would run hot but seldom a real boil over problem save for a few ocassions of plugged up radiator cores. We always ran a 50/50 antifreeze solution which raises the boiling point slightly.