Thermostats
- Thread starter patrick flowers
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OK, so I now understand that the engine is designed to operate with a 195=B0
stat. and I should get rid of the 165=B0 one I have in there now. But I
recall some comment that all thermostats didn't have the same size opening
when activated.
It makes sense that when the engine reaches 195=B0, a thertmostat with
greater flow capacity will help prevent overheating. So that I can have the
right one installed, can someone please tell me which one has the larger
opening.
TIA (thanks in advance), Dave
ps: Can someone help me feel a little less ignorant by explaining what the
abreviations YMMV and IIRC mean? I may not be the only one who doesn't
know.
stat. and I should get rid of the 165=B0 one I have in there now. But I
recall some comment that all thermostats didn't have the same size opening
when activated.
It makes sense that when the engine reaches 195=B0, a thertmostat with
greater flow capacity will help prevent overheating. So that I can have the
right one installed, can someone please tell me which one has the larger
opening.
TIA (thanks in advance), Dave
ps: Can someone help me feel a little less ignorant by explaining what the
abreviations YMMV and IIRC mean? I may not be the only one who doesn't
know.
The following statement is ridiculous, " Thermostat temperatures do
determine the
temperature of the engine block."
Tom, Do you really believe that? If so, then I have a bridge to sell
you. Thermostats only insure that the coolant temperature comes up to
the rated level and have nothing to do with the maximum engine running
temperature of the engine block unless the rated temperature of the
thermostat exceeds all the other factors involved in the cooling system
not to mention the outside air temperature and the load placed on the
vehicle. If this statement were true, I wouldn't need to worry about
the whole cooling system, only to run a lower rated thermostat. Oh, if
only life were that simple!
Regards, Phil Swanson
determine the
temperature of the engine block."
Tom, Do you really believe that? If so, then I have a bridge to sell
you. Thermostats only insure that the coolant temperature comes up to
the rated level and have nothing to do with the maximum engine running
temperature of the engine block unless the rated temperature of the
thermostat exceeds all the other factors involved in the cooling system
not to mention the outside air temperature and the load placed on the
vehicle. If this statement were true, I wouldn't need to worry about
the whole cooling system, only to run a lower rated thermostat. Oh, if
only life were that simple!
Regards, Phil Swanson
However, once the fuel and air is in the cylinder, and the valves close
for
compression, we want to keep as much of the heat generated as possible
therein, so that it can expand those gasses and PUSH on that piston!
Excellant statement!! This is why I stated earlier that "Heat is Energy"
in an internal combustion engine. It is this expansion that gives us
power to the crankshaft and wheels. Not to be confused with cool air
induction.
Phil
Swanson
for
compression, we want to keep as much of the heat generated as possible
therein, so that it can expand those gasses and PUSH on that piston!
Excellant statement!! This is why I stated earlier that "Heat is Energy"
in an internal combustion engine. It is this expansion that gives us
power to the crankshaft and wheels. Not to be confused with cool air
induction.
Phil
Swanson
Phil lets preface this discussion with a couple of assumptions that pertain
to all engines and not just the GMC.
1. The block is not severely rusted inside the water passages to impact the
flow of water and all designed coolant passages to the block and heads are
open as designed.
2. The correct water pump is installed for the engine.
3. The radiator is properly sized for the engine and its intended use.
4. Water hoses to and from the radiator are in good shape and do not
collapse under use.
5. Water flow path within the engine and radiator does not have any trapped
air.
6. Cooling fan is working as designed.
7. We don't confuse the underhood engine compartment ambient temperature
with that of the engine block.
All of these assumptions being satisfied, than the thermostat determines the
temperature of the coolant within the block and very closely the temperature
of the engine block, ie; there is some teperature gradient throughout the
block determined by the proximity of coolant to the combustion surface.
1. When the engine is first started, the thermostat is fully closed and
water does not circulate through the radiator, but only within the engine block.
2. As it reaches the thermostat temperature of 195 degrees, the thermostat
opens (if you watch the temperature gauge you can see the thermostat open
and the temp drop) allowing coolant from the radiator to circulate in the
engine until the temperature of the coolant drops below the thermostat value
at which time the thermostat closes again, and coolant flow stops again to
the radiator.
3. This opening and closing cycle continues during the complete time the
engine is running. The coolant temperature will stay at 195 degrees even
when the engine is idling for long periods of time, as long as the the
radiator system is capable of dissipating the excess energy above 195 degrees.
I am not aware of how the temperature could exceed the thermostat
temperature if the above conditions are met. but I am willing to learn.
>The following statement is ridiculous, " Thermostat temperatures do
>determine the
>temperature of the engine block."
>
>Tom, Do you really believe that? If so, then I have a bridge to sell
>you. Thermostats only insure that the coolant temperature comes up to
>the rated level and have nothing to do with the maximum engine running
>temperature of the engine block unless the rated temperature of the
>thermostat exceeds all the other factors involved in the cooling system
>not to mention the outside air temperature and the load placed on the
>vehicle. If this statement were true, I wouldn't need to worry about
>the whole cooling system, only to run a lower rated thermostat. Oh, if
>only life were that simple!
>
> Regards, Phil Swanson
>
>
>
to all engines and not just the GMC.
1. The block is not severely rusted inside the water passages to impact the
flow of water and all designed coolant passages to the block and heads are
open as designed.
2. The correct water pump is installed for the engine.
3. The radiator is properly sized for the engine and its intended use.
4. Water hoses to and from the radiator are in good shape and do not
collapse under use.
5. Water flow path within the engine and radiator does not have any trapped
air.
6. Cooling fan is working as designed.
7. We don't confuse the underhood engine compartment ambient temperature
with that of the engine block.
All of these assumptions being satisfied, than the thermostat determines the
temperature of the coolant within the block and very closely the temperature
of the engine block, ie; there is some teperature gradient throughout the
block determined by the proximity of coolant to the combustion surface.
1. When the engine is first started, the thermostat is fully closed and
water does not circulate through the radiator, but only within the engine block.
2. As it reaches the thermostat temperature of 195 degrees, the thermostat
opens (if you watch the temperature gauge you can see the thermostat open
and the temp drop) allowing coolant from the radiator to circulate in the
engine until the temperature of the coolant drops below the thermostat value
at which time the thermostat closes again, and coolant flow stops again to
the radiator.
3. This opening and closing cycle continues during the complete time the
engine is running. The coolant temperature will stay at 195 degrees even
when the engine is idling for long periods of time, as long as the the
radiator system is capable of dissipating the excess energy above 195 degrees.
I am not aware of how the temperature could exceed the thermostat
temperature if the above conditions are met. but I am willing to learn.
>The following statement is ridiculous, " Thermostat temperatures do
>determine the
>temperature of the engine block."
>
>Tom, Do you really believe that? If so, then I have a bridge to sell
>you. Thermostats only insure that the coolant temperature comes up to
>the rated level and have nothing to do with the maximum engine running
>temperature of the engine block unless the rated temperature of the
>thermostat exceeds all the other factors involved in the cooling system
>not to mention the outside air temperature and the load placed on the
>vehicle. If this statement were true, I wouldn't need to worry about
>the whole cooling system, only to run a lower rated thermostat. Oh, if
>only life were that simple!
>
> Regards, Phil Swanson
>
>
>
Been following the thermostat discussion and finally can't resist to add my
2cents worth as no one has discussed real life, actual temperatures.
I run a sensor in the normal place, but digital and also a thermocouple
which is fastened on one of the thermostat hood bolts, also digital. Both
are very fast acting, i.e. no or very little lag.
When my GMC is cruising/loafing the temperature is approx 208 degrees. It'll
go up with terrain as well as with traffic jams. In stop'n go traffic of a
few hours it is not uncommon to see 225-230 and then the fan clutch kicks in
to bring it back down. Same for going up long hills, i.e. the Grapevine into
LA or I10 out of LA, etc.
So, for what it's worth (IMHO) the function of the thermostat is to get the
engine up to operating temperature faster, i.e. without having to heat all
the liquid in the radiator and more importantly (again IMHO) it's function
is to prevent rapid temperature fluctuations. i.e. rapid cooldown when
coasting down a long hill, etc. I believe it is much more harmfull to an
engine to fluctuate between 165 and 208 vs 195 and 208. I do agree however
that whatever thermostat is in use it should allow for maximum flow when
wide open, the position that all of 'em are in under most normal driving
conditions.
Just my 2 pennies worth.
Heinz
'76 Transmode, 230k+.
2cents worth as no one has discussed real life, actual temperatures.
I run a sensor in the normal place, but digital and also a thermocouple
which is fastened on one of the thermostat hood bolts, also digital. Both
are very fast acting, i.e. no or very little lag.
When my GMC is cruising/loafing the temperature is approx 208 degrees. It'll
go up with terrain as well as with traffic jams. In stop'n go traffic of a
few hours it is not uncommon to see 225-230 and then the fan clutch kicks in
to bring it back down. Same for going up long hills, i.e. the Grapevine into
LA or I10 out of LA, etc.
So, for what it's worth (IMHO) the function of the thermostat is to get the
engine up to operating temperature faster, i.e. without having to heat all
the liquid in the radiator and more importantly (again IMHO) it's function
is to prevent rapid temperature fluctuations. i.e. rapid cooldown when
coasting down a long hill, etc. I believe it is much more harmfull to an
engine to fluctuate between 165 and 208 vs 195 and 208. I do agree however
that whatever thermostat is in use it should allow for maximum flow when
wide open, the position that all of 'em are in under most normal driving
conditions.
Just my 2 pennies worth.
Heinz
'76 Transmode, 230k+.
Since I started this thread, (and have gotten my answer, Thank You all), I
should get to add a comment. There has been some really excellent
discussion on controlling the temperatures of our engines, and following
them has certainly added to my understanding. But I can see where some
might still be confused, especially with the disagreements regarding the
effects of modifications.
1) A properly working thermostat, after regulating the warm up cycle,
controls the MINIMUM operating temperature. The coolant will always be AT
LEAST as hot as the thermostat rating. The only way the thermostat could
affect MAXIMUM temperature would be by excessively restricting coolant
flow.
2) It's true that many of those expensive improvements CAN reduce engine
temperatures. But ONLY when those temps are above the thermostat rating. No
matter how effective,they won't bring temperatures down below the
thermostat rating.
I will take whatever steps I can (afford) to keep my engine's temperature
as close as possible to 195 degrees.
Just another $.02
Dave
should get to add a comment. There has been some really excellent
discussion on controlling the temperatures of our engines, and following
them has certainly added to my understanding. But I can see where some
might still be confused, especially with the disagreements regarding the
effects of modifications.
1) A properly working thermostat, after regulating the warm up cycle,
controls the MINIMUM operating temperature. The coolant will always be AT
LEAST as hot as the thermostat rating. The only way the thermostat could
affect MAXIMUM temperature would be by excessively restricting coolant
flow.
2) It's true that many of those expensive improvements CAN reduce engine
temperatures. But ONLY when those temps are above the thermostat rating. No
matter how effective,they won't bring temperatures down below the
thermostat rating.
I will take whatever steps I can (afford) to keep my engine's temperature
as close as possible to 195 degrees.
Just another $.02
Dave
