Understanding Thermostat Temps

[67 GTX]

Hello All,

First off, just want to say I've read a bunch of threads on this forum about thermostats, how they operate, and what everyone's preference is.
I am not looking for an argument to start up (which seems to on everyone thermostat thread), but I am still wondering a few things:

1. Why doesn't a 160 thermostat get used more to help with cooling?
1a. I've read the manuals and I know our cars mainly came with 180s. But I thought common practice back in the day was 160 for the summer, 180 for colder temps.
1b. If a car runs hot with a 180/195, and lets say the cooling system is all correct and working (including pump, fan, shroud, how much the fan sticks out of the shroud), wouldn't a 160 cool the engine off some more?
1b1. I've read that too cool of an engine isn't optimal and I understand why, but as 160 could keep the temp around 180 for example, then that would be sufficient no?

2. Has anyone used Gates thermostats? I noticed that have a standard one, and then an alternate (premium) one that appears to have the thermostat open a little sooner than the standard one?

Thank you ahead of time!

 

[R413]

I do what you are asking about, a 160 is reaching full open sooner and can make it work on some cars. Other just keep getting hotter until you fix the problem. Different cars need different things and a 160 does work on some of them.

I don't understand everyone going off on 160 thermostats, same guys insist on a hi flow, hi volume, high pressure, hi amperage overkill everything, which is foolish to me.

 

[j-c-c-62]

"1b. If a car runs hot with a 180/195, and lets say the cooling system is all correct and working (including pump, fan, shroud, how much the fan sticks out of the shroud), wouldn't a 160 cool the engine off some more?

IMO the engine will at some point reach a thermo equilibrium. Any temp rated thermostat will help accelerate the reaching of that point, unless the system has over cooling capacity (it should), and the thermostat then will dial in on that temp and maintain it. Cooling always revolves around the temp delta, meaning the difference between the hot side (the engine) and the cold side (the cooling system, ambient air, etc), or the greater the difference, the more the cooling exchange is taking place, until a thermo balance is reached.

 

[WileE]

An engine runs most efficiently when the temp is about 195F to about 210F. Higher or lower has consequences. I've always preferred a 180 since that's when the t-stat opens, and the operating temps will usually be higher especially in warm/hot weather.

 

[twecomm]

Keep in mind that engine timing can have a significant effect on engine operating temperature..

 

[67 GTX]

I run a 160 thermostat, mopar performance pump (seems identical to a stock one, just aluminum), stock radiator (but might have been altered to 4 core, I believe stock was 3), stock fan and shroud, and fan clutch (I might remove the clutch). Also have the all in timing set to 35 degrees.
Pretty much a stock 440.

I had to car out today on a long drive (hot and humid), and it seemed to hold between 190-200.

Could a radiator cap do anything? Only reason I am asking, my car would normally run around 215-220 on a day like today. All I changed a few weeks ago was the radiator cap. But I changed like for like. If let's say the old cap wasn't building up proper pressure, does the pressure help the cooling ability?

 

[j-c-c-62]

Yes, in that helps resist hot spots internally that boil the water reducing heat transfer if the cap maintains pressure properly. Not sure it that was a problem that a new cap corrected.

 

[67 GTX]

Yes, in that helps resist hot spots internally that boil the water reducing heat transfer if the cap maintains pressure properly. Not sure it that was a problem that a new cap corrected.

Thank you. That could be something. I didn't have any other theory so that's one.

 

[451Mopar]

I run a 160 in the Charger, but it is more a strip car than street.
The Coronet has the 180 degree driving on the street with EFI. Some of the self learning EFIs don't go into the self-learn mode until after 160-170 degrees.

 

[theman440]

An engine runs most efficiently when the temp is about 195F to about 210F. Higher or lower has consequences. I've always preferred a 180 since that's when the t-stat opens, and the operating temps will usually be higher especially in warm/hot weather.

^^^ What he said^^^ Not to mention the engine stays cleaner !

 

[67 GTX]

2. Has anyone used Gates thermostats? I noticed that have a standard one, and then an alternate (premium) one that appears to have the thermostat open a little sooner than the standard one?

Thank you ahead of time!

Has anyone tried that premium thermostat?

 

[WileE]

If let's say the old cap wasn't building up proper pressure, does the pressure help the cooling ability?

The pressure increases the boiling point of the coolant. If you have an air bubble, or pocket, it cannot absorb the heat as the liquid can. By pressurizing and increasing the boiling point, it maintains the coolant in a liquid state to enable absorption of heat generated from the cylinders.

 

[RR Fan Dan]

The pressure increases the boiling point of the coolant. If you have an air bubble, or pocket, it cannot absorb the heat as the liquid can. By pressurizing and increasing the boiling point, it maintains the coolant in a liquid state to enable absorption of heat generated from the cylinders.

Atmosphere at sea level is 14.7, graphs are above atmosphere. So a 12 pound cap is good to prevent boiling up to about 240 degrees without coolant.

 

[WileE]

Atmosphere at sea level is 14.7, graphs are above atmosphere. So a 12 pound cap is good to prevent boiling up to about 240 degrees without coolant.

Important point of pressure at sea level. Atmospheric pressure decreases as altitude increases.

 

[1970Moparmann]

Interesting thread! Out of all of the cars I owned, I always had them running on the higher end of 180. Just had my 400 rebuilt and when it is hot and humid, it runs on the lower range of 180/185 and can get up to 220 if sitting in traffic. With all this being said, what temp is when you have to let them cool off? Based on the graph above is it 240?

 

[Ron H]

Here’s what I have understood about thermostats: in cold climates a higher temp stat is desired as it heats up the coolant in the block before it releases coolant to the block from the radiator. Faster heat means more window defrosting and cabin heat sooner. Being in a cold climate, there are winter days when it can’t happen soon enough. It has little effect on operating temperature. It will be the same, though with a lower stat it may take a couple minutes longer to reach it since the changeover from the radiator occurs at a lower temp. Debates on a 160 vs 180, IMO doesn’t mean much. I run a 160 as my ride is only driven in summer and hibernates in a heated garage. I run a 70/30 anti-freeze mix, debatable, but I’ve read that anti-freeze retains heat more than water. Another tidbit, debatable? Not running a stat at all. I’ve been told that the stat does inhibit some flow and is beneficial by design for the radiator to have more time to do what it’s intended...cool the coolant running through it.

 

[RR Fan Dan]

With all this being said, what temp is when you have to let them cool off? Based on the graph above is it 240?

That temp is without coolant. Get you an antifreeze tester to know for sure what the temp will be. That temp is also where it starts to boil and not effective. But that being said if you had enough antifreeze in it to keep it from boiling to 350 F , I don’t think you would want to run it that hot because you would start wiping bearings. Get you an antifreeze tester, and you will know exactly what protection you have,

 

[RR Fan Dan]

Important point of pressure at sea level. Atmospheric pressure decreases as altitude increases.

Yes if you live at high altitudes you need to make adjustments.