Mike Romain

Cherokee-LTD wrote:
>
> "Shaggie" <travist34@snotmail.com> wrote in message
> news:c6rt9u$f8k1h$2@ID-163201.news.uni-berlin.de...
> : Shaggie <travist34@snotmail.com> wrote in news:c6rpnv$ff063$1@ID-
> : 163201.news.uni-berlin.de:
> :
> : >
> : >>:
> : >> Bring a lower t-stat and some tools with you as well.
> : >> -Brian
> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

A 160 t-stat and a 195 t-stat are physically the same size. When fully
open they both allow the same flow.

When the engine internally reaches 160, the first one opens. When the
engine internally hits 195, the second one opens.

Once the engine has passed this 160 or 195 degree mark, the thermostat
never budges from wide open.

Take a TJ for instance. No matter what t-stat you put in it, it 'will'
run at 210 degrees. It just warms up faster with the hotter t-stat.

This means in the winter when the fan can supercool the rad, you will
only see 160 degree water in the heater core and will freeze your butt
off with the cold t-stat. With the 195, you will have heat inside the
vehicle.

Thermostats are only for the low temperature control, not for top end
heat.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Mike Romain

Cherokee-LTD wrote:
>
> "Shaggie" <travist34@snotmail.com> wrote in message
> news:c6rt9u$f8k1h$2@ID-163201.news.uni-berlin.de...
> : Shaggie <travist34@snotmail.com> wrote in news:c6rpnv$ff063$1@ID-
> : 163201.news.uni-berlin.de:
> :
> : >
> : >>:
> : >> Bring a lower t-stat and some tools with you as well.
> : >> -Brian
> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

A 160 t-stat and a 195 t-stat are physically the same size. When fully
open they both allow the same flow.

When the engine internally reaches 160, the first one opens. When the
engine internally hits 195, the second one opens.

Once the engine has passed this 160 or 195 degree mark, the thermostat
never budges from wide open.

Take a TJ for instance. No matter what t-stat you put in it, it 'will'
run at 210 degrees. It just warms up faster with the hotter t-stat.

This means in the winter when the fan can supercool the rad, you will
only see 160 degree water in the heater core and will freeze your butt
off with the cold t-stat. With the 195, you will have heat inside the
vehicle.

Thermostats are only for the low temperature control, not for top end
heat.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Mike Romain

Cherokee-LTD wrote:
>
> "Shaggie" <travist34@snotmail.com> wrote in message
> news:c6rt9u$f8k1h$2@ID-163201.news.uni-berlin.de...
> : Shaggie <travist34@snotmail.com> wrote in news:c6rpnv$ff063$1@ID-
> : 163201.news.uni-berlin.de:
> :
> : >
> : >>:
> : >> Bring a lower t-stat and some tools with you as well.
> : >> -Brian
> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

A 160 t-stat and a 195 t-stat are physically the same size. When fully
open they both allow the same flow.

When the engine internally reaches 160, the first one opens. When the
engine internally hits 195, the second one opens.

Once the engine has passed this 160 or 195 degree mark, the thermostat
never budges from wide open.

Take a TJ for instance. No matter what t-stat you put in it, it 'will'
run at 210 degrees. It just warms up faster with the hotter t-stat.

This means in the winter when the fan can supercool the rad, you will
only see 160 degree water in the heater core and will freeze your butt
off with the cold t-stat. With the 195, you will have heat inside the
vehicle.

Thermostats are only for the low temperature control, not for top end
heat.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

J. Painter

Brian:

Mike is actually correct. I remember this issue distinctly even from
twenty-something years ago when I was in class at Lincoln Technical
Institute learning to become an automotive mechanic. It has always
been a source of confusion. Perhaps the issue can best be explained
this way:

The thermostat sets the FLOOR operating temperature. That is, the
MINIMUM operating temperature. For example, a 195 degree thermostat
will not fully open until that approximate temperature has been
reached on the ENGINE BLOCK side of the cooling system loop. (Of
course, actual coolant temps right next to the cylinder walls will be
somewhat higher.) Once that temperature has been reached, the
thermostat opens to allow coolant to flow into the radiator.
Typically, as Mike points out, this process takes place during engine
warmup of the first 10-20 minutes, depending on driving conditions and
ambient temps. Once the engine is warmed up, the thermostat is
typically wide open and does little except provide a restricted
passageway that the engineers predetermined would be correct for
optimal coolant flow. That is why taking the thermostat out can be
problematic. Only in extremely cold weather would the thermostat
continue to open and close in order to maintain the minimum operating
temperature.

Now, this begs the question: how DO you change the coolant operating
temperature if not through changing thermostats? Well, the original
engineers determined what they thought to be the optimal operating
temperature in order to maximize fuel milage and performance, then
they designed the size of the radiator, the flow rate of the water
pump, the airflow of the grill, the shroud and the fan, the
passageways in the engine block, and other factors so that that
temperature would be maintained under most driving conditions. Fan
clutches and electric fans controlled by computer made it possible for
some adjustment during driving. Anyone that has been stuck in an
August afternoon on a hot highway with the A/C running can attest that
the cooling system has limitations in design!

So, for the Jeeper who wants to increase cooling capacity, aftermarket
radiators with more fins, water pumps with higher flow rates, and
higher performance electric fans and shrouds would be the way to go.
However, it would appear that most Jeeps were designed to run and be
happy around 210 degrees. Unless your engine is highly modified and no
longer is computer controlled, you should probably leave well enough
alone. If trail conditions are forcing your temps well above 210, then
probably a higher-performance radiator would be enough to bring the
temps back down.

In any case, cooler thermostat will only set a lower operating floor,
which would mean coolant flowing into the engine block sooner than it
should. That means a confused computer, a choke that is improperly
set, and probably reduced milage and performance for the 10 minutes or
so it will take for the engine to fully warm up. Once the engine is
warmed, the cooler thermostat will probably not change anything,
assuming the orifice is the same as the stock unit and the weather
conditions are in some normal range.

J Painter



> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

J. Painter

Brian:

Mike is actually correct. I remember this issue distinctly even from
twenty-something years ago when I was in class at Lincoln Technical
Institute learning to become an automotive mechanic. It has always
been a source of confusion. Perhaps the issue can best be explained
this way:

The thermostat sets the FLOOR operating temperature. That is, the
MINIMUM operating temperature. For example, a 195 degree thermostat
will not fully open until that approximate temperature has been
reached on the ENGINE BLOCK side of the cooling system loop. (Of
course, actual coolant temps right next to the cylinder walls will be
somewhat higher.) Once that temperature has been reached, the
thermostat opens to allow coolant to flow into the radiator.
Typically, as Mike points out, this process takes place during engine
warmup of the first 10-20 minutes, depending on driving conditions and
ambient temps. Once the engine is warmed up, the thermostat is
typically wide open and does little except provide a restricted
passageway that the engineers predetermined would be correct for
optimal coolant flow. That is why taking the thermostat out can be
problematic. Only in extremely cold weather would the thermostat
continue to open and close in order to maintain the minimum operating
temperature.

Now, this begs the question: how DO you change the coolant operating
temperature if not through changing thermostats? Well, the original
engineers determined what they thought to be the optimal operating
temperature in order to maximize fuel milage and performance, then
they designed the size of the radiator, the flow rate of the water
pump, the airflow of the grill, the shroud and the fan, the
passageways in the engine block, and other factors so that that
temperature would be maintained under most driving conditions. Fan
clutches and electric fans controlled by computer made it possible for
some adjustment during driving. Anyone that has been stuck in an
August afternoon on a hot highway with the A/C running can attest that
the cooling system has limitations in design!

So, for the Jeeper who wants to increase cooling capacity, aftermarket
radiators with more fins, water pumps with higher flow rates, and
higher performance electric fans and shrouds would be the way to go.
However, it would appear that most Jeeps were designed to run and be
happy around 210 degrees. Unless your engine is highly modified and no
longer is computer controlled, you should probably leave well enough
alone. If trail conditions are forcing your temps well above 210, then
probably a higher-performance radiator would be enough to bring the
temps back down.

In any case, cooler thermostat will only set a lower operating floor,
which would mean coolant flowing into the engine block sooner than it
should. That means a confused computer, a choke that is improperly
set, and probably reduced milage and performance for the 10 minutes or
so it will take for the engine to fully warm up. Once the engine is
warmed, the cooler thermostat will probably not change anything,
assuming the orifice is the same as the stock unit and the weather
conditions are in some normal range.

J Painter



> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

J. Painter

Brian:

Mike is actually correct. I remember this issue distinctly even from
twenty-something years ago when I was in class at Lincoln Technical
Institute learning to become an automotive mechanic. It has always
been a source of confusion. Perhaps the issue can best be explained
this way:

The thermostat sets the FLOOR operating temperature. That is, the
MINIMUM operating temperature. For example, a 195 degree thermostat
will not fully open until that approximate temperature has been
reached on the ENGINE BLOCK side of the cooling system loop. (Of
course, actual coolant temps right next to the cylinder walls will be
somewhat higher.) Once that temperature has been reached, the
thermostat opens to allow coolant to flow into the radiator.
Typically, as Mike points out, this process takes place during engine
warmup of the first 10-20 minutes, depending on driving conditions and
ambient temps. Once the engine is warmed up, the thermostat is
typically wide open and does little except provide a restricted
passageway that the engineers predetermined would be correct for
optimal coolant flow. That is why taking the thermostat out can be
problematic. Only in extremely cold weather would the thermostat
continue to open and close in order to maintain the minimum operating
temperature.

Now, this begs the question: how DO you change the coolant operating
temperature if not through changing thermostats? Well, the original
engineers determined what they thought to be the optimal operating
temperature in order to maximize fuel milage and performance, then
they designed the size of the radiator, the flow rate of the water
pump, the airflow of the grill, the shroud and the fan, the
passageways in the engine block, and other factors so that that
temperature would be maintained under most driving conditions. Fan
clutches and electric fans controlled by computer made it possible for
some adjustment during driving. Anyone that has been stuck in an
August afternoon on a hot highway with the A/C running can attest that
the cooling system has limitations in design!

So, for the Jeeper who wants to increase cooling capacity, aftermarket
radiators with more fins, water pumps with higher flow rates, and
higher performance electric fans and shrouds would be the way to go.
However, it would appear that most Jeeps were designed to run and be
happy around 210 degrees. Unless your engine is highly modified and no
longer is computer controlled, you should probably leave well enough
alone. If trail conditions are forcing your temps well above 210, then
probably a higher-performance radiator would be enough to bring the
temps back down.

In any case, cooler thermostat will only set a lower operating floor,
which would mean coolant flowing into the engine block sooner than it
should. That means a confused computer, a choke that is improperly
set, and probably reduced milage and performance for the 10 minutes or
so it will take for the engine to fully warm up. Once the engine is
warmed, the cooler thermostat will probably not change anything,
assuming the orifice is the same as the stock unit and the weather
conditions are in some normal range.

J Painter



> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

J. Painter

Brian:

Mike is actually correct. I remember this issue distinctly even from
twenty-something years ago when I was in class at Lincoln Technical
Institute learning to become an automotive mechanic. It has always
been a source of confusion. Perhaps the issue can best be explained
this way:

The thermostat sets the FLOOR operating temperature. That is, the
MINIMUM operating temperature. For example, a 195 degree thermostat
will not fully open until that approximate temperature has been
reached on the ENGINE BLOCK side of the cooling system loop. (Of
course, actual coolant temps right next to the cylinder walls will be
somewhat higher.) Once that temperature has been reached, the
thermostat opens to allow coolant to flow into the radiator.
Typically, as Mike points out, this process takes place during engine
warmup of the first 10-20 minutes, depending on driving conditions and
ambient temps. Once the engine is warmed up, the thermostat is
typically wide open and does little except provide a restricted
passageway that the engineers predetermined would be correct for
optimal coolant flow. That is why taking the thermostat out can be
problematic. Only in extremely cold weather would the thermostat
continue to open and close in order to maintain the minimum operating
temperature.

Now, this begs the question: how DO you change the coolant operating
temperature if not through changing thermostats? Well, the original
engineers determined what they thought to be the optimal operating
temperature in order to maximize fuel milage and performance, then
they designed the size of the radiator, the flow rate of the water
pump, the airflow of the grill, the shroud and the fan, the
passageways in the engine block, and other factors so that that
temperature would be maintained under most driving conditions. Fan
clutches and electric fans controlled by computer made it possible for
some adjustment during driving. Anyone that has been stuck in an
August afternoon on a hot highway with the A/C running can attest that
the cooling system has limitations in design!

So, for the Jeeper who wants to increase cooling capacity, aftermarket
radiators with more fins, water pumps with higher flow rates, and
higher performance electric fans and shrouds would be the way to go.
However, it would appear that most Jeeps were designed to run and be
happy around 210 degrees. Unless your engine is highly modified and no
longer is computer controlled, you should probably leave well enough
alone. If trail conditions are forcing your temps well above 210, then
probably a higher-performance radiator would be enough to bring the
temps back down.

In any case, cooler thermostat will only set a lower operating floor,
which would mean coolant flowing into the engine block sooner than it
should. That means a confused computer, a choke that is improperly
set, and probably reduced milage and performance for the 10 minutes or
so it will take for the engine to fully warm up. Once the engine is
warmed, the cooler thermostat will probably not change anything,
assuming the orifice is the same as the stock unit and the weather
conditions are in some normal range.

J Painter



> :
> : Brian, why did you say that? Mike says the thermostat only is relevant
> : during the warmup period of the engine.
> :
> : --
>
> I respectfully disagree with Mike. The t-stat is a metering valve just like
> adjusting the tap on your garden hose. A cooler t-stat slows the flow and
> allows your rad enough time to cool it's capacity.
>
> Your original post didn't mention your operating temperature - just that it
> was hotter than before. My recommendation for a cooler t-stat addresses a
> faulty t-stat (sticking open) and compensating for the changes you made for
> your fuel delivery system.... all for about $5.00.
>
> If you're running 210, you're fine. If you see it creeping above 225 keep a
> close eye on it. If you see prolonged 230+ you may have 'issues'.
>
> -Brian

Alan

> Once the engine is warmed up, the thermostat is
> typically wide open and does little except provide a restricted
> passageway that the engineers predetermined would be correct for
> optimal coolant flow. That is why taking the thermostat out can be
> problematic. Only in extremely cold weather would the thermostat
> continue to open and close in order to maintain the minimum operating
> temperature.

Given that the heat generated in the engine is significantly different at idle
and at full throttle, I find it hard to believe that there is a single point
that would be the correct flow rate.

I have changed thermostats in several cars and had the "steady state"
temperature change to be the new termostats rated temp.

I guess I disagree with the statement that "only in extrememly cold weather
would the thermostat continue to open and close in order to maintain the minimum
operating tempurature".

Unless of course a regular 20-40 degree Ohio spring/fall morning is "extrememly
cold" to some southern writer...

alan

Alan

> Once the engine is warmed up, the thermostat is
> typically wide open and does little except provide a restricted
> passageway that the engineers predetermined would be correct for
> optimal coolant flow. That is why taking the thermostat out can be
> problematic. Only in extremely cold weather would the thermostat
> continue to open and close in order to maintain the minimum operating
> temperature.

Given that the heat generated in the engine is significantly different at idle
and at full throttle, I find it hard to believe that there is a single point
that would be the correct flow rate.

I have changed thermostats in several cars and had the "steady state"
temperature change to be the new termostats rated temp.

I guess I disagree with the statement that "only in extrememly cold weather
would the thermostat continue to open and close in order to maintain the minimum
operating tempurature".

Unless of course a regular 20-40 degree Ohio spring/fall morning is "extrememly
cold" to some southern writer...

alan

Alan

> Once the engine is warmed up, the thermostat is
> typically wide open and does little except provide a restricted
> passageway that the engineers predetermined would be correct for
> optimal coolant flow. That is why taking the thermostat out can be
> problematic. Only in extremely cold weather would the thermostat
> continue to open and close in order to maintain the minimum operating
> temperature.

Given that the heat generated in the engine is significantly different at idle
and at full throttle, I find it hard to believe that there is a single point
that would be the correct flow rate.

I have changed thermostats in several cars and had the "steady state"
temperature change to be the new termostats rated temp.

I guess I disagree with the statement that "only in extrememly cold weather
would the thermostat continue to open and close in order to maintain the minimum
operating tempurature".

Unless of course a regular 20-40 degree Ohio spring/fall morning is "extrememly
cold" to some southern writer...

alan