81 vette running hot help
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
Ali....
My bet is your radiator lower tubes have clogged...this drastically reduces cooling efficiency...have your radiator flushed...that may/or may not fix problem...
Highly recomend you run correct thermostat...this allows engine to warm up properly for oil circulation....the stat has nothing to do with engine operating temps once stat opens...if you run without stat,your engine WILL experience excessive wear internally....
Rich
My bet is your radiator lower tubes have clogged...this drastically reduces cooling efficiency...have your radiator flushed...that may/or may not fix problem...
Highly recomend you run correct thermostat...this allows engine to warm up properly for oil circulation....the stat has nothing to do with engine operating temps once stat opens...if you run without stat,your engine WILL experience excessive wear internally....
Rich
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
200º without AC and 220º with AC is not excessively hot and if you are not puking coolant out than you really aren't overheating. My '78 L82 - 100% stock - typically runs 200º - 215º with or without the AC on. Since it still has the stock 195º t-stat it won't run less than 195º anyway.
if yours runs those temps in all conditions, idle, low speed, high speed etc than your cooling system is most likely operating fine and about the only thing you can probably do is upgrade your factory radiator to a DeWitts aluminum one and drop your t-stat down to a 180º to take advantage of the better cooling capacity of the new radiator.
Remember, the t-stat itself won't determine the maximum operating temp, just the minimum operating temp, but if the new radiator cools well enough and everything else in the cooling system is up to par than the radiator can in many cases keep your operating temps at where the t-stat level is. So, by getting better cooling capacity by the new, better radiator than lowering the t-stat to a 180º may allow the system to run cooler (because of the radiator, not the t-stat).
if yours runs those temps in all conditions, idle, low speed, high speed etc than your cooling system is most likely operating fine and about the only thing you can probably do is upgrade your factory radiator to a DeWitts aluminum one and drop your t-stat down to a 180º to take advantage of the better cooling capacity of the new radiator.
Remember, the t-stat itself won't determine the maximum operating temp, just the minimum operating temp, but if the new radiator cools well enough and everything else in the cooling system is up to par than the radiator can in many cases keep your operating temps at where the t-stat level is. So, by getting better cooling capacity by the new, better radiator than lowering the t-stat to a 180º may allow the system to run cooler (because of the radiator, not the t-stat).
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Because it belongs there!!
the t-stat won't affect your maximum operating temps at all but it's there to dicate your minimum operating temps and more importantly it's there to block coolant flow during warm-up to help the car get to operating temps more quickly, reducing cylinder bore and piston ring wear.
Believe me, if a t-stat was not necessary GM would not have put them in. They didn't put parts on a car just because they could. The cooling system was engineered as it is for a reason, it worked.
the t-stat won't affect your maximum operating temps at all but it's there to dicate your minimum operating temps and more importantly it's there to block coolant flow during warm-up to help the car get to operating temps more quickly, reducing cylinder bore and piston ring wear.
Believe me, if a t-stat was not necessary GM would not have put them in. They didn't put parts on a car just because they could. The cooling system was engineered as it is for a reason, it worked.
Race Director
Joined: Feb 2005
Posts: 16,100
Likes: 17
[QUOTE=BarryK;1565252590 My '78 L82 - 100% stock - typically runs 200º - 215º with or without the AC on. Since it still has the stock 195º t-stat it won't run less [/QUOTE]
You are right on that...200-215 well within safe operating range...I bought my 78 L-82 in 1979...running A/C climbing long grades in the desert it never exceeded 210...
However,over time,my C/B rad began clogging in lower tubes and efficiency dropped,and coolant temps reached 220-230 in desert ambient air temps (110 F)even though flush helped some...the Dewitts has made big difference/180 stat...in same conditions,coolant temps do not exceed 200 F with A/C on...
You are right on that...200-215 well within safe operating range...I bought my 78 L-82 in 1979...running A/C climbing long grades in the desert it never exceeded 210...
However,over time,my C/B rad began clogging in lower tubes and efficiency dropped,and coolant temps reached 220-230 in desert ambient air temps (110 F)even though flush helped some...the Dewitts has made big difference/180 stat...in same conditions,coolant temps do not exceed 200 F with A/C on...
Race Director
Joined: Mar 2008
Posts: 15,161
Likes: 17
From: coffee
the 180 degree t-stat opens at a cooler temperature (180* F vs. 195*F). This effectively regulates what temperature the engine operates at as the thermostat will open when the coolant reaches the designed temperature and the radiator is then able to keep the temperature of the coolant to an acceptible operating temperature.
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Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
Factory went to a 195º unit back in early 70's because of emissions requirements (same time as they switched vacuum advance from full manifold vacuum to ported vacuum and other emission "solutions").
The idea was that with the higher operating temps it helped burn off excessive hydrocarbons therefore reducing emissions levels.
If you still have all the factory emissions equipment on your car you should stay with a 195º t-stat so that everything works properly. If the emissions equipment has been removed from your car than run a 180º t-stat.
Regardless of the t-stat run YOUR motor will run at whatever maximum operating temps it wants based on the condition of your cooling system, NOT the t-stat since as already mentioned the t-stat only controls what the minimum operating temp will be
Theoretically, if your cooling system is in top condition and everything is perfect (doesn't happen often) the cooling system could keep the operating temps right about what the t-stat temp value is since the cooling system would remove any excess heat from the system above the t-stat temp rating but in more cases than not this doesn't happen in real life.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
Seriously, the 195 thermostat was for getting the engine warmer to pass emmisions testing. Many of us have replaced it with the 180, but if you are running 200 degrees, the thermostat is open either way unless it is bad. God bless, Sensei
Le Mans Master
Joined: Jan 2006
Posts: 9,192
Likes: 27
From: Boca Raton Florida
15 degrees
The t-stat sets the lower operating temp on the engine, in other words it forces the enging to run at least at the temp on the t-stat. A 180* t-stat will let the engine run 15* cooler than a 195* t-stat.
If your engine is runniong hot due to something with the thermostat it is because the t-stat is not opening or not opening enough.
Generally when a thermostat fails it sticks closed and the engin will get very hot very quickly.
Your engine is only running a little high, not bad at all.
The fan clutch or some obstruction IN the radiator or ON the radiator or some combination is your problem.
The t-stat sets the lower operating temp on the engine, in other words it forces the enging to run at least at the temp on the t-stat. A 180* t-stat will let the engine run 15* cooler than a 195* t-stat.
If your engine is runniong hot due to something with the thermostat it is because the t-stat is not opening or not opening enough.
Generally when a thermostat fails it sticks closed and the engin will get very hot very quickly.
Your engine is only running a little high, not bad at all.
The fan clutch or some obstruction IN the radiator or ON the radiator or some combination is your problem.
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
here is an excellent article for you to look over - it may help and will give you a much better understanding of each component of the cooling system and how they are designed to work together to handle the cooling of your car
http://lbfun.com/Corvette/Tech/vette...es/cooling.pdf
http://lbfun.com/Corvette/Tech/vette...es/cooling.pdf
Race Director
Joined: Mar 2008
Posts: 15,161
Likes: 17
From: coffee
You must have an obstruction in your system somewhere, or the T-stat has failed completely and will not open.
If you remove the t-stat and put it in a pot of boiling water, to see if it will open that should tell you whether it is working or not. After that, you will just have to check your hoses, water pump, etc..
If you remove the t-stat and put it in a pot of boiling water, to see if it will open that should tell you whether it is working or not. After that, you will just have to check your hoses, water pump, etc..
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
What have toy done so far to check thru your cooling system other than needlessly remove the t-stat?
I see no posts from you stating you have checked the actual temp with an IR temp gauge instead of relying in what the temp sender & gauge has told you, that you have checked proper operation of the water pump and coolant flow, checked your timing, checked the radiator for debris or other obstructions that would impede airflow, had the radiator flushed and/or checked for major deposits that would impede cooling capacity, checked operation of your fan clutch, checked that the correct air dam is in place under the nose, checked that all the radiator and core support seals are in place, etc, etc.
you are asking for help but are not giving us any information to work with to help you.
