160 degree vs 180 degree thermostat

[WPVT]

The replacement thermostat for my 1954 218 flat head is available in a 160 degree version or 180 degree version. I am replacing the thermostat because the gauge showed it running a bit hot, but now I realize that was because it probably had a 180 degree thermostat in it. I like to see the gauge right in the middle, but is there any other reason to use the 160 instead of the 180 degree version ? I'm not going to be running the truck in the winter, and there isn't a heater anyway. 

[Plymouthy Adams]

other than build up sludge faster....your call on the centering of the needle on the gauge.....as these gauges are not truly accurate, you state you guessing at the temp as you did not state verification with an gauge tested for accuracy.  

[WPVT]

36 minutes ago, Plymouthy Adams said:

other than build up sludge faster....your call on the centering of the needle on the gauge.....as these gauges are not truly accurate, you state you guessing at the temp as you did not state verification with an gauge tested for accuracy.  

I just get a little jumpy when I see a temp gauge past center. Old habit. 

[Plymouthy Adams]

I hear you but to me that is REASON to test properly before changing anything....but then, that is just who I am

[RobertKB]

Use a laser temperature gun to check actual temps at various points on the engine. 

[greg g]

The thermostat determines when the bypass opens allowing coolant to circulation to the radiator. It's secondary purpose is to provide a restriction to the rate of flow  of coolant through the radiator, if it passes througn it returns to the engine tooh too quickly it doesn't cool as much as it should.  Then the warmer coolant absorb the amount of heat that it should be carrying out.  The degree temp rating doesn't really have a lot to do with the normal operating temperature of the engine. A 180 stat doesn't mean your engine runs at 180.  Most folks get nervous when the needle sits at 190 because they are thinking of water boiling ar 212, forgetting that 50 50 mix is good to 230 before it begins to boil.  Most engines more efficiently around 190 or even more in newer cars. Also, think of air-cooled engines, they run a lot hotter they are made of the same stuff and they don't melt as long as there is oil in them. They usually run at 250 plus and 3 to 4 hundred under load. 

 

The first question when you get hot under the collar should be how hot is hot?  Then how hot is too hot?

 

 

[billschwindt]

That engine will run better at 180 -190 and for sure stay cleaner inside .

[Sniper]

If you really want to geek out on cooling system data here's a paper with all the math you could want in calculating efficiencies.  Much data is collected and used.  If you look at the data the two factors that really make a difference is temperature differential, either between the engine and coolant, or coolant and air, with the greater the differential the more efficient.  The other is flow rate, with more flow being more effective.  Think about it, do we slow down the air flow thru the radiator to allow the air "more time to cool"?  Nope, because that's not how it works and it doesn't work that way for coolant flow either.  There is one case where a restriction to coolant flow is valid though, when the engine is turning so fast the water pump will cavitate.  In this case a restriction to flow can remediate that to some degree.  This usually is only found in racing and is where the "restriction is good" thinking came from.  It's fine to do things, but you need to know why it's done and if it's useful for you. 

 

One thing I found with my 51 is that the radiator fins were full of fine dust.  A good power cleaning helped.

 

 

Edited August 31, 2021 by Sniper

[kencombs]

1 hour ago, Sniper said:

 

 

One thing I found with my 51 is that the radiator fins were full of fine dust.  A good power cleaning helped.

 

 

I've found that to be really common, especially with Mopar honeycomb cores.  And, often overlooked as a cause of overheating at highway speeds.

I use a garden sprayer or a siphon gun and air hose to soak the core with a cleaner intended for air conditioner coil cleaning.  Then use my pressure washer with the widest angle tip and lower pressure than normal to blow the junk out.  With the pressure washer it's important to NOT hit the core at angle at  high pressure as it will bend the fins.

 

[WPVT]

Thanks for all of your input. I ordered a 160 degree thermostat and I'll install it this week. I never had an overheating problem. I could see the thermostat doing its job by watching the temperature gauge. My comment about the needle was only that I had noticed that normal running had the gauge at 1 o'clock, rather than 12 o'clock, something that really makes no difference. That was just the result of using a 180 degree thermostat instead of the 160 degree that the gauge was designed for. The thermostat still opened and closed and kept the water at the temperature it was supposed to, and that was evident from watching the needle.

If I had a heater in the truck, I'd probably go with the 180 degree thermostat, but I don't. 

Thanks again.  

 

 

 

 

[kencombs]

Let us know the result when the stat is changed.  I would expect no difference in running temp except in lower air temps.  Just a difference in opening temp.