How cool is to cool
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Race Director
Joined: Dec 1999
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From: Forked River NJ
How cool is to cool
I drove my car about 100 miles yesterday and the temps were around 65 degrees all day. While running even on the highway at a constant 2200 rpm my temp gauge was on the low side. When I got home I checked with my IR gun and at the thermostat I was reading 145 to 150 degrees little warmer at other locations. I have a high flow 180 thermostat (fairly new) stock LT1 rad and a electric fan. Everything was running fine and I'm not complaining but I know they start to lose effeincy if they get to cool. The fan is not running and it will heat up if I let it sit and idle.
Heel & Toe
Joined: Oct 2005
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Mine runs around 175. I posted a similar question over at Corvette crew cuz I thought it was cool. Mine was the coolest with the highest running 210. They do make 160 Deg themostats, sure you don't have one of those? How long does it take to get up to temp?
Safety Car
Joined: Aug 2000
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From: San Antonio TX
The thermostat regulates the coolest the engine will operate at once it comes up to temp. In your case, assuming a functioning thermostat, you should have 180 degees at the thermostat outlet. The water won't flow until you hit the stat's number. So, you weren't using the IR right or your thermostat is stuck open.
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
On the highway mine runs at about 150 degrees on cooler days, just means the rad is getting enough cool air and it doesn't matter what fan or thermostat you have at this point that is the temp it is going to run.
The only way to get it run hotter would be to block off part of the rad, then you would have overheating problems when you come off the highway
The only way to get it run hotter would be to block off part of the rad, then you would have overheating problems when you come off the highway
Instructor
Joined: Jan 2005
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From: Huntington Beach CA
We just had this debate on our 1980 C3, we were running at about 195 - 200 with a 195 thermo. The water pump went so I decided to do a complete overhaul of the cooling system. I've replaced the water pump, pulled and flushed the rad and replaced the thermo with a 180. Now the car runs rock steady at 180 and even cooler stationary. If I give it some gas I can get it to push 190-200 but it pretty quickly comes down.
I'm of the opinion it's better to run cooler rather than hotter even though the engine is actually more efficient at the higher temperatures. But in SoCal and 100 degree days you tend to want to stay low...
I'm of the opinion it's better to run cooler rather than hotter even though the engine is actually more efficient at the higher temperatures. But in SoCal and 100 degree days you tend to want to stay low...
Thread Starter
Race Director
Joined: Dec 1999
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From: Forked River NJ
I'm sure it is a 180. I had the package for a while and it is even stamped on the t stat 180. In the summer it runs fine just as the temps get cooler It seems to be low. Yes I have used an IR gun for many years. I know the t stat is working because it will warm up then open and you see the gauge drop a little then it stabalizes itself.
Race Director
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Originally Posted by MotorHead
On the highway mine runs at about 150 degrees on cooler days, just means the rad is getting enough cool air and it doesn't matter what fan or thermostat you have at this point that is the temp it is going to run.
The only way to get it run hotter would be to block off part of the rad, then you would have overheating problems when you come off the highway
The only way to get it run hotter would be to block off part of the rad, then you would have overheating problems when you come off the highway
actually that's not true, the thermostat does not regulate the max. temp, that's a result of the maximum cooling capacity of the entire system and the stat fully open..
However, the minimum hot running temperature is affected by the thermostat, if yours is @ 150 degrees and you have a higher rated stat then there's a couple of things that can cause this. Either the stat is not closing, the gauge isn't reading correctly, the gauge is in the radiator tank or above the thermostat and not in the cylinder head or the outside cool air actually cools the engine itself from the cool air passing by. If the rad cools off the coolant such that after flowing through the engine and it's under the rated closing temp of the stat then the thermostat should close so there's no circulation through the rad/flow of cooler coonat in and the coolant in the engine will get warmer.
On transverse placed engines you see this a lot, the engine not warming up very well at highway speeds, this is due to the large engine surface exposed to the cold head on air flowing by.
Safety Car
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From: San Antonio TX
It really can't run cooler than the t-stat rating. The only difference in cooling performance between summer and winter is that if the system is marginal, the temp will run hotter than 180 (or whatever the stat is rated at) in the summer time under adverse condition, while maintaining proper temp in colder air. Cooler weather masks cooling systems on the edge.
If your system has enough capacity to cover the most adverse summer conditions, it will still run at the minimum 180 even in winter.
There are some occasions when extreme cold weather will not allow the coolant to come up to temp, like in the Arctic, and that's where you find folks blocking the airflow through the radiator fins with cardbroard to slow the heat transfer.
If the t-stat is doing its job, it will stall water circulation in the engine until the coolant is hot enough to open the stat.
I'd be tempted to put a kitchen thermometer in the circulating coolant to see if it agrees with your IR thermometer.
If you really are running that low, it's something that I would address.
If your system has enough capacity to cover the most adverse summer conditions, it will still run at the minimum 180 even in winter.
There are some occasions when extreme cold weather will not allow the coolant to come up to temp, like in the Arctic, and that's where you find folks blocking the airflow through the radiator fins with cardbroard to slow the heat transfer.
If the t-stat is doing its job, it will stall water circulation in the engine until the coolant is hot enough to open the stat.
I'd be tempted to put a kitchen thermometer in the circulating coolant to see if it agrees with your IR thermometer.
If you really are running that low, it's something that I would address.
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Race Director
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From: Waterloo ontario Canada
Originally Posted by MotorHead
On the highway mine runs at about 150 degrees on cooler days, just means the rad is getting enough cool air and it doesn't matter what fan or thermostat you have at this point that is the temp it is going to run.
The only way to get it run hotter would be to block off part of the rad, then you would have overheating problems when you come off the highway
The only way to get it run hotter would be to block off part of the rad, then you would have overheating problems when you come off the highway
If you are running down the highway and your temp is 150 you do not have a working thermostat.
Your cooling system regulates the maximum temperature not the minimum
Thread Starter
Race Director
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From: Forked River NJ
Come to think about it I changed the T stat about 2 years ago. It has run cool on cool days ever since then. On hot days it does run around 180 to 190. I'll have to pull it and put in the old 180 and see how it goes. My water neck is not a chrome one. I have seen where a shiny surface will give a bad reading on an IR gun.
Team Owner
Joined: Jul 1999
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From: Huntersville NC
So, if the thermostat is functioning properly the water temp must be 180 up by the stat, but then it gets cooled way down in the radiator and only heats up to 150 as it passes by the temp sending unit and doesnt get heated up to 180 until it is in front of the stat again. I guess that makes sense. The concern is... remember that graph that charted engine wear as a function of operating temp? There was a very convincing article posted a while back in one of our many and lengthy discussions of the merits of 190 vs 180 vs 160 vs NO stat. As I recall the ideal temp was around 185-190, you didn't really pick up much extra wear at 175- 180 but if you ran cooler than that you could significantly reduce your engine life. Might be worth another look.
Race Director
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The best pos. for the temp sender is in the cyl head because that's where the majority of the heat is passed into the coolant, that's where most of the warming up occurs. The temperature is not the same all over the engine block, if it's 180 at the stat or a little higher...but enough to open it it's probably more like 200 or een hotter at the ehads, that's why it's pretty much impossible to have a 180 stat and reading 150 at the gauge w/ the sender in the head, having the sender in the radiator tank however will do it.
Race Director
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From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Originally Posted by MotorHead
On the highway mine runs at about 150 degrees on cooler days, just means the rad is getting enough cool air and it doesn't matter what fan or thermostat you have at this point that is the temp it is going to run.
OK I should have said the engine is getting enough cool air and it doesn't matter what the rest of the cooling system is doing. I have a tried two brand new thermostats and new temp gauge.
I am pretty sure this air cooling is correct because I once ran my Grand Am with no water for a week in the winter 99% of the time on the highway at it ran cool, the only thing cooling the motor would have been the ambient temp and cool air hitting the motor at highway speeds. I think the same thing is happening with the Vette
Fire away flame suit is locked and loaded
Le Mans Master
Joined: Nov 2004
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From: detroit area
since i don't have a thermostat and i took out my heater core and looped that hose and have a recored radiator and stock fan, i run around 140-160 even after running for about 3 hours during a cruise/sitting in still traffic......
b
b
Race Director
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From: In Dreams There Is Truth Ohio
It doesn't matter what the coolant temperature is...what's important that the oil temp is around 240 degrees...temps above 260-270, better cool it down, and temps below 220, find a way to get it up to 240...
Race Director
Joined: Feb 2005
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The boiling water test is good for checking a stat that "fails closed"....in this case,it either is stuck open,or something else is happening...and no thermostat controls engine maximum "operating temperature".....just holds back coolant till stat opens on warm up...
Last edited by rihwoods; Oct 17, 2005 at 03:56 PM.