removing the thermostat

"Do not remove the thermostat in
the engine cooling system as this
may cause the engine to overheat.
The thermostat is designed to con-
trol the flow of coolant to keep the
temperature of the engine within
the specified operating range"

From a Toyota manual. I thought removing the thermostat could cause
the engine to underheat, never reach proper operating temperature.

Do I know more about this than Toyota?

On 20/09/2017 9:25 PM, micky wrote:
> "Do not remove the thermostat in
> the engine cooling system as this
> may cause the engine to overheat.
> The thermostat is designed to con-
> trol the flow of coolant to keep the
> temperature of the engine within
> the specified operating range"
>
> From a Toyota manual. I thought removing the thermostat could cause
> the engine to underheat, never reach proper operating temperature.
>
> Do I know more about this than Toyota?
>
That depends entirely on the function(s) of the thermostat.

In general, you are correct. In more specific terms, it depends.

The thermostat's most basic function is to bring the car up to
temperature from cold quickly. It does that by blocking off coolant flow
to the radiator. Note that the coolant will still need to continue to
circulate around the cylinder block and head. It does that through the
use of a bypass mechanism.
The other function of a thermostat is to maintain the temperature above
a set minimum temperature. For example, when you are going downhill, the
throttle will be closed and minimal, if any, fuel will enter the
cylinders to be combusted. In that situation, the cooling in the
radiator will drop the temperature below the specified setting. The
thermostat will close, isolating the radiator, thereby preventing any
further temperature drop. The same thing will occur if the radiator is
oversized. If the cooling system is too efficient, the radiator may
overcool even during light throttle cruising.

The issue of overheating can be caused by a *secondary function of some
thermostats, This will explain it in detail;

http://www.are.com.au/feat/techt/thermostat.htm

It's not a new idea by any means. I had this *feature* in cars of the
60s and 70s.

The problem of overheating will occur without a thermostat or with an
incorrect thermostat fitted.

HTH


--

Xeno

On 9/20/2017 10:26 AM, Xeno wrote:
> On 20/09/2017 9:25 PM, micky wrote:
>> "Do not remove the thermostat in
>> the engine cooling system as this
>> may cause the engine to overheat.
>> The thermostat is designed to con-
>> trol the flow of coolant to keep the
>> temperature of the engine within
>> the specified operating range"
>>
>> Â*From a Toyota manual.Â*Â* I thought removing the thermostat could cause
>> the engine to underheat, never reach proper operating temperature.
>>
>> Do I know more about this than Toyota?
>>
> That depends entirely on the function(s) of the thermostat.
>
> In general, you are correct. In more specific terms, it depends.
>
> The thermostat's most basic function is to bring the car up to
> temperature from cold quickly. It does that by blocking off coolant flow
> to the radiator. Note that the coolant will still need to continue to
> circulate around the cylinder block and head. It does that through the
> use of a bypass mechanism.
> The other function of a thermostat is to maintain the temperature above
> a set minimum temperature. For example, when you are going downhill, the
> throttle will be closed and minimal, if any, fuel will enter the
> cylinders to be combusted. In that situation, the cooling in the
> radiator will drop the temperature below the specified setting. The
> thermostat will close, isolating the radiator, thereby preventing any
> further temperature drop. The same thing will occur if the radiator is
> oversized. If the cooling system is too efficient, the radiator may
> overcool even during light throttle cruising.
>
> The issue of overheating can be caused by a *secondary function of some
> thermostats, This will explain it in detail;
>
> Â* http://www.are.com.au/feat/techt/thermostat.htm
>
> It's not a new idea by any means. I had this *feature* in cars of the
> 60s and 70s.
>
> The problem of overheating will occur without a thermostat or with an
> incorrect thermostat fitted.
>
> HTH

It is a misconception that a the absence of a thermostat
will result in overheating; it WILL NOT. The resulting
high flow rate may however collapse a hose and restrict
flow if the hose is either weak walled or missing an
"inflating" spring.

On 21/09/2017 1:48 AM, . wrote:
> On 9/20/2017 10:26 AM, Xeno wrote:
>> On 20/09/2017 9:25 PM, micky wrote:
>>> "Do not remove the thermostat in
>>> the engine cooling system as this
>>> may cause the engine to overheat.
>>> The thermostat is designed to con-
>>> trol the flow of coolant to keep the
>>> temperature of the engine within
>>> the specified operating range"
>>>
>>> Â*From a Toyota manual.Â*Â* I thought removing the thermostat could cause
>>> the engine to underheat, never reach proper operating temperature.
>>>
>>> Do I know more about this than Toyota?
>>>
>> That depends entirely on the function(s) of the thermostat.
>>
>> In general, you are correct. In more specific terms, it depends.
>>
>> The thermostat's most basic function is to bring the car up to
>> temperature from cold quickly. It does that by blocking off coolant
>> flow to the radiator. Note that the coolant will still need to
>> continue to circulate around the cylinder block and head. It does that
>> through the use of a bypass mechanism.
>> The other function of a thermostat is to maintain the temperature
>> above a set minimum temperature. For example, when you are going
>> downhill, the throttle will be closed and minimal, if any, fuel will
>> enter the cylinders to be combusted. In that situation, the cooling in
>> the radiator will drop the temperature below the specified setting.
>> The thermostat will close, isolating the radiator, thereby preventing
>> any further temperature drop. The same thing will occur if the
>> radiator is oversized. If the cooling system is too efficient, the
>> radiator may overcool even during light throttle cruising.
>>
>> The issue of overheating can be caused by a *secondary function of
>> some thermostats, This will explain it in detail;
>>
>> Â*Â* http://www.are.com.au/feat/techt/thermostat.htm
>>
>> It's not a new idea by any means. I had this *feature* in cars of the
>> 60s and 70s.
>>
>> The problem of overheating will occur without a thermostat or with an
>> incorrect thermostat fitted.
>>
>> HTH
>
> It is a misconception that a the absence of a thermostat
> will result in overheating; it WILL NOT. The resulting
> high flow rate may however collapse a hose and restrict
> flow if the hose is either weak walled or missing an
> "inflating" spring.

Nothing to do with a high flow rate collapsing a hose. That sort of
event requires a *restriction to flow*, usually upstream of the water
pump, that creates a low pressure area. That means it's usually the
bottom radiator hose collapsing due to a restricted flow radiator. The
thermostat is on the outflow side of the pump.

The scenario to which I am referring is where the coolant takes the path
of least resistance, hence the need for a bypass valve. The diagrams in
the link I provided should have made that clear.

What actually happens is that the water flow will take the path of least
resistance which, in the case of the cooling system, will be the shorter
bypass circuit back through the block.

You will still be getting flow through the radiator but the percentage
lost back through the bypass means that the effect may only be felt
under load or during times of extreme ambient temperature. That
certainly has been my experience. One such car I had required a
thermostat with two valves. Since I bought the car used, I didn't know
that it had the incorrect one fitted, the one sans the bypass valve.
That meant the bypass circuit wasn't restricted in any way. This car
performed perfectly, never overheated, during normal operation. I only
discovered the incorrect thermostat had been fitted when traveling on
summer holidays with a fully loaded car on 40C+ days on the highways
with lots of long hills. That small amount of lost cooling effect was
just enough to tip the balance.
On other makes and models, they could boil even under mild conditions
and removing the thermostat entirely is no guarantee. It certainly
wasn't in my case even though the flow area in the region of the
thermostat effectively doubled. A new correct thermostat solved the issue.

--

Xeno

On 9/21/2017 1:26 AM, Xeno wrote:
> On 21/09/2017 1:48 AM, . wrote:
>> On 9/20/2017 10:26 AM, Xeno wrote:
>>> On 20/09/2017 9:25 PM, micky wrote:
>>>> "Do not remove the thermostat in
>>>> the engine cooling system as this
>>>> may cause the engine to overheat.
>>>> The thermostat is designed to con-
>>>> trol the flow of coolant to keep the
>>>> temperature of the engine within
>>>> the specified operating range"
>>>>
>>>> Â*From a Toyota manual.Â*Â* I thought removing the thermostat could cause
>>>> the engine to underheat, never reach proper operating temperature.
>>>>
>>>> Do I know more about this than Toyota?
>>>>
>>> That depends entirely on the function(s) of the thermostat.
>>>
>>> In general, you are correct. In more specific terms, it depends.
>>>
>>> The thermostat's most basic function is to bring the car up to
>>> temperature from cold quickly. It does that by blocking off coolant
>>> flow to the radiator. Note that the coolant will still need to
>>> continue to circulate around the cylinder block and head. It does
>>> that through the use of a bypass mechanism.
>>> The other function of a thermostat is to maintain the temperature
>>> above a set minimum temperature. For example, when you are going
>>> downhill, the throttle will be closed and minimal, if any, fuel will
>>> enter the cylinders to be combusted. In that situation, the cooling
>>> in the radiator will drop the temperature below the specified
>>> setting. The thermostat will close, isolating the radiator, thereby
>>> preventing any further temperature drop. The same thing will occur if
>>> the radiator is oversized. If the cooling system is too efficient,
>>> the radiator may overcool even during light throttle cruising.
>>>
>>> The issue of overheating can be caused by a *secondary function of
>>> some thermostats, This will explain it in detail;
>>>
>>> Â*Â* http://www.are.com.au/feat/techt/thermostat.htm
>>>
>>> It's not a new idea by any means. I had this *feature* in cars of the
>>> 60s and 70s.
>>>
>>> The problem of overheating will occur without a thermostat or with an
>>> incorrect thermostat fitted.
>>>
>>> HTH
>>
>> It is a misconception that a the absence of a thermostat
>> will result in overheating; it WILL NOT. The resulting
>> high flow rate may however collapse a hose and restrict
>> flow if the hose is either weak walled or missing an
>> "inflating" spring.
>
> Nothing to do with a high flow rate collapsing a hose. That sort of
> event requires a *restriction to flow*, usually upstream of the water
> pump, that creates a low pressure area. That means it's usually the
> bottom radiator hose collapsing due to a restricted flow radiator. The
> thermostat is on the outflow side of the pump.

And the sky is blue and water is wet.

> The scenario to which I am referring is where the coolant takes the path
> of least resistance, hence the need for a bypass valve. The diagrams in
> the link I provided should have made that clear. >
> What actually happens is that the water flow will take the path of least
> resistance which, in the case of the cooling system, will be the shorter
> bypass circuit back through the block.

Bypass circuits are more restricted than the normal
flow AND you obviously don't understand parallel flow.

> You will still be getting flow through the radiator but the percentage
> lost back through the bypass means that the effect may only be felt
> under load or during times of extreme ambient temperature. That
> certainly has been my experience. One such car I had required a
> thermostat with two valves. Since I bought the car used, I didn't know
> that it had the incorrect one fitted, the one sans the bypass valve.
> That meant the bypass circuit wasn't restricted in any way. This car
> performed perfectly, never overheated, during normal operation. I only
> discovered the incorrect thermostat had been fitted when traveling on
> summer holidays with a fully loaded car on 40C+ days on the highways
> with lots of long hills. That small amount of lost cooling effect was
> just enough to tip the balance.
> On other makes and models, they could boil even under mild conditions
> and removing the thermostat entirely is no guarantee. It certainly
> wasn't in my case even though the flow area in the region of the
> thermostat effectively doubled. A new correct thermostat solved the issue.

Just a lot of nonsense: if you're claiming that an
engine will run hotter without a thermostat, then
you are simply wrong.

On 21/09/2017 10:36 PM, . wrote:
> On 9/21/2017 1:26 AM, Xeno wrote:
>> On 21/09/2017 1:48 AM, . wrote:
>>> On 9/20/2017 10:26 AM, Xeno wrote:
>>>> On 20/09/2017 9:25 PM, micky wrote:
>>>>> "Do not remove the thermostat in
>>>>> the engine cooling system as this
>>>>> may cause the engine to overheat.
>>>>> The thermostat is designed to con-
>>>>> trol the flow of coolant to keep the
>>>>> temperature of the engine within
>>>>> the specified operating range"
>>>>>
>>>>> Â*From a Toyota manual.Â*Â* I thought removing the thermostat could cause
>>>>> the engine to underheat, never reach proper operating temperature.
>>>>>
>>>>> Do I know more about this than Toyota?
>>>>>
>>>> That depends entirely on the function(s) of the thermostat.
>>>>
>>>> In general, you are correct. In more specific terms, it depends.
>>>>
>>>> The thermostat's most basic function is to bring the car up to
>>>> temperature from cold quickly. It does that by blocking off coolant
>>>> flow to the radiator. Note that the coolant will still need to
>>>> continue to circulate around the cylinder block and head. It does
>>>> that through the use of a bypass mechanism.
>>>> The other function of a thermostat is to maintain the temperature
>>>> above a set minimum temperature. For example, when you are going
>>>> downhill, the throttle will be closed and minimal, if any, fuel will
>>>> enter the cylinders to be combusted. In that situation, the cooling
>>>> in the radiator will drop the temperature below the specified
>>>> setting. The thermostat will close, isolating the radiator, thereby
>>>> preventing any further temperature drop. The same thing will occur
>>>> if the radiator is oversized. If the cooling system is too
>>>> efficient, the radiator may overcool even during light throttle
>>>> cruising.
>>>>
>>>> The issue of overheating can be caused by a *secondary function of
>>>> some thermostats, This will explain it in detail;
>>>>
>>>> Â*Â* http://www.are.com.au/feat/techt/thermostat.htm
>>>>
>>>> It's not a new idea by any means. I had this *feature* in cars of
>>>> the 60s and 70s.
>>>>
>>>> The problem of overheating will occur without a thermostat or with
>>>> an incorrect thermostat fitted.
>>>>
>>>> HTH
>>>
>>> It is a misconception that a the absence of a thermostat
>>> will result in overheating; it WILL NOT. The resulting
>>> high flow rate may however collapse a hose and restrict
>>> flow if the hose is either weak walled or missing an
>>> "inflating" spring.
>>
>> Nothing to do with a high flow rate collapsing a hose. That sort of
>> event requires a *restriction to flow*, usually upstream of the water
>> pump, that creates a low pressure area. That means it's usually the
>> bottom radiator hose collapsing due to a restricted flow radiator. The
>> thermostat is on the outflow side of the pump.
>
> And the sky is blue and water is wet.
>
>> The scenario to which I am referring is where the coolant takes the
>> path of least resistance, hence the need for a bypass valve. The
>> diagrams in the link I provided should have made that clear. >
>> What actually happens is that the water flow will take the path of
>> least resistance which, in the case of the cooling system, will be the
>> shorter bypass circuit back through the block.
>
> Bypass circuits are more restricted than the normal
> flow AND you obviously don't understand parallel flow.
>
>> You will still be getting flow through the radiator but the percentage
>> lost back through the bypass means that the effect may only be felt
>> under load or during times of extreme ambient temperature. That
>> certainly has been my experience. One such car I had required a
>> thermostat with two valves. Since I bought the car used, I didn't know
>> that it had the incorrect one fitted, the one sans the bypass valve.
>> That meant the bypass circuit wasn't restricted in any way. This car
>> performed perfectly, never overheated, during normal operation. I only
>> discovered the incorrect thermostat had been fitted when traveling on
>> summer holidays with a fully loaded car on 40C+ days on the highways
>> with lots of long hills. That small amount of lost cooling effect was
>> just enough to tip the balance.
>> On other makes and models, they could boil even under mild conditions
>> and removing the thermostat entirely is no guarantee. It certainly
>> wasn't in my case even though the flow area in the region of the
>> thermostat effectively doubled. A new correct thermostat solved the
>> issue.
>
> Just a lot of nonsense: if you're claiming that an
> engine will run hotter without a thermostat, then
> you are simply wrong.

It is not me claiming it. It is the auto manufacturers making that
claim. I have *experienced it first hand*. I can vouch for the
possibility of overheating due to the complete absence of a thermostat
or the fitment of the incorrect type of thermostat. It's all due to
cooling system design.

I have no problem understanding parallel flows. What occurs in the case
of cars with a bypass shutoff thermostat is that the bypass flow is
removed from the circuit. All coolant is forced to run through the
radiator. If the wrong thermostat is fitted, one that cannot shut off
the bypass circuit, then a percentage of the coolant flow will flow
through the bypass circuit and *not be cooled*. The risk of overheating
will be determined by two factors, the percentage of the flow bypassing
the radiator, and the load factor on the engine. A third factor which
can come into play here is the age of the radiator and the percentage of
blockage it is experiencing. It may be the case where it would take
extreme conditions to create the overheating situation, as was the case
with my vehicle, or it could be occurring under normal conditions. That
is all dependent on the design of the cooling system and the reserve
capacity built into the radiator.

Regardless - overheating has occurred in the field else the
manufacturers would not be issuing the warning.

--

Xeno

On 9/21/2017 9:42 AM, Xeno wrote:
> On 21/09/2017 10:36 PM, . wrote:
>> On 9/21/2017 1:26 AM, Xeno wrote:
>>> On 21/09/2017 1:48 AM, . wrote:
>>>> On 9/20/2017 10:26 AM, Xeno wrote:
>>>>> On 20/09/2017 9:25 PM, micky wrote:
>>>>>> "Do not remove the thermostat in
>>>>>> the engine cooling system as this
>>>>>> may cause the engine to overheat.
>>>>>> The thermostat is designed to con-
>>>>>> trol the flow of coolant to keep the
>>>>>> temperature of the engine within
>>>>>> the specified operating range"
>>>>>>
>>>>>> Â*From a Toyota manual.Â*Â* I thought removing the thermostat could
>>>>>> cause
>>>>>> the engine to underheat, never reach proper operating temperature.
>>>>>>
>>>>>> Do I know more about this than Toyota?
>>>>>>
>>>>> That depends entirely on the function(s) of the thermostat.
>>>>>
>>>>> In general, you are correct. In more specific terms, it depends.
>>>>>
>>>>> The thermostat's most basic function is to bring the car up to
>>>>> temperature from cold quickly. It does that by blocking off coolant
>>>>> flow to the radiator. Note that the coolant will still need to
>>>>> continue to circulate around the cylinder block and head. It does
>>>>> that through the use of a bypass mechanism.
>>>>> The other function of a thermostat is to maintain the temperature
>>>>> above a set minimum temperature. For example, when you are going
>>>>> downhill, the throttle will be closed and minimal, if any, fuel
>>>>> will enter the cylinders to be combusted. In that situation, the
>>>>> cooling in the radiator will drop the temperature below the
>>>>> specified setting. The thermostat will close, isolating the
>>>>> radiator, thereby preventing any further temperature drop. The same
>>>>> thing will occur if the radiator is oversized. If the cooling
>>>>> system is too efficient, the radiator may overcool even during
>>>>> light throttle cruising.
>>>>>
>>>>> The issue of overheating can be caused by a *secondary function of
>>>>> some thermostats, This will explain it in detail;
>>>>>
>>>>> Â*Â* http://www.are.com.au/feat/techt/thermostat.htm
>>>>>
>>>>> It's not a new idea by any means. I had this *feature* in cars of
>>>>> the 60s and 70s.
>>>>>
>>>>> The problem of overheating will occur without a thermostat or with
>>>>> an incorrect thermostat fitted.
>>>>>
>>>>> HTH
>>>>
>>>> It is a misconception that a the absence of a thermostat
>>>> will result in overheating; it WILL NOT. The resulting
>>>> high flow rate may however collapse a hose and restrict
>>>> flow if the hose is either weak walled or missing an
>>>> "inflating" spring.
>>>
>>> Nothing to do with a high flow rate collapsing a hose. That sort of
>>> event requires a *restriction to flow*, usually upstream of the water
>>> pump, that creates a low pressure area. That means it's usually the
>>> bottom radiator hose collapsing due to a restricted flow radiator.
>>> The thermostat is on the outflow side of the pump.
>>
>> And the sky is blue and water is wet.
>>
>>> The scenario to which I am referring is where the coolant takes the
>>> path of least resistance, hence the need for a bypass valve. The
>>> diagrams in the link I provided should have made that clear. >
>>> What actually happens is that the water flow will take the path of
>>> least resistance which, in the case of the cooling system, will be
>>> the shorter bypass circuit back through the block.
>>
>> Bypass circuits are more restricted than the normal
>> flow AND you obviously don't understand parallel flow.
>>
>>> You will still be getting flow through the radiator but the
>>> percentage lost back through the bypass means that the effect may
>>> only be felt under load or during times of extreme ambient
>>> temperature. That certainly has been my experience. One such car I
>>> had required a thermostat with two valves. Since I bought the car
>>> used, I didn't know that it had the incorrect one fitted, the one
>>> sans the bypass valve. That meant the bypass circuit wasn't
>>> restricted in any way. This car performed perfectly, never
>>> overheated, during normal operation. I only discovered the incorrect
>>> thermostat had been fitted when traveling on summer holidays with a
>>> fully loaded car on 40C+ days on the highways with lots of long
>>> hills. That small amount of lost cooling effect was just enough to
>>> tip the balance.
>>> On other makes and models, they could boil even under mild conditions
>>> and removing the thermostat entirely is no guarantee. It certainly
>>> wasn't in my case even though the flow area in the region of the
>>> thermostat effectively doubled. A new correct thermostat solved the
>>> issue.
>>
>> Just a lot of nonsense: if you're claiming that an
>> engine will run hotter without a thermostat, then
>> you are simply wrong.
>
> It is not me claiming it. It is the auto manufacturers making that
> claim. I have *experienced it first hand*. I can vouch for the
> possibility of overheating due to the complete absence of a thermostat
> or the fitment of the incorrect type of thermostat. It's all due to
> cooling system design.
>
> I have no problem understanding parallel flows. What occurs in the case
> of cars with a bypass shutoff thermostat is that the bypass flow is
> removed from the circuit. All coolant is forced to run through the
> radiator. If the wrong thermostat is fitted, one that cannot shut off
> the bypass circuit, then a percentage of the coolant flow will flow
> through the bypass circuit and *not be cooled*. The risk of overheating
> will be determined by two factors, the percentage of the flow bypassing
> the radiator, and the load factor on the engine. A third factor which
> can come into play here is the age of the radiator and the percentage of
> blockage it is experiencing. It may be the case where it would take
> extreme conditions to create the overheating situation, as was the case
> with my vehicle, or it could be occurring under normal conditions. That
> is all dependent on the design of the cooling system and the reserve
> capacity built into the radiator.
>
> Regardless - overheating has occurred in the field else the
> manufacturers would not be issuing the warning.

Cite so much as a SINGLE example of any engine or vehicle
manufacturer supporting a claim of overheating due to
the absence of a thermostat. What they DON'T like is the
increased wear and open loop operation that can result
from its absence.

On Wednesday, September 20, 2017 at 1:25:51 AM UTC-10, micky wrote:
> "Do not remove the thermostat in
> the engine cooling system as this
> may cause the engine to overheat.
> The thermostat is designed to con-
> trol the flow of coolant to keep the
> temperature of the engine within
> the specified operating range"
>
> From a Toyota manual. I thought removing the thermostat could cause
> the engine to underheat, never reach proper operating temperature.
>
> Do I know more about this than Toyota?

My guess is that you don't know more about this than Toyota. If you use a regular type thermostat on a system that requires a bypass type thermostat, part of the coolant is going to bypass the radiator. How much coolant is going to bypass the radiator? I don't know but my guess is that the coolant is going to flow in the path of least resistance and that path is probably not through the radiator.

If your engine overheats and the cooling system appears to be working properly, it would be a good idea to check if you're using the correct thermostat.

On 9/21/2017 12:00 PM, dsi1 wrote:
> On Wednesday, September 20, 2017 at 1:25:51 AM UTC-10, micky wrote:
>> "Do not remove the thermostat in
>> the engine cooling system as this
>> may cause the engine to overheat.
>> The thermostat is designed to con-
>> trol the flow of coolant to keep the
>> temperature of the engine within
>> the specified operating range"
>>
>> From a Toyota manual. I thought removing the thermostat could cause
>> the engine to underheat, never reach proper operating temperature.
>>
>> Do I know more about this than Toyota?
>
> My guess is that you don't know more about this than Toyota. If you use a regular type thermostat on a system that requires a bypass type thermostat, part of the coolant is going to bypass the radiator. How much coolant is going to bypass the radiator? I don't know but my guess is that the coolant is going to flow in the path of least resistance and that path is probably not through the radiator.

No, the bypass system is of smaller cross sectional
area and more restrictive than that of the normal
path to and through the radiator.

> If your engine overheats and the cooling system appears to be working properly, it would be a good idea to check if you're using the correct thermostat.

On Thursday, September 21, 2017 at 7:14:51 AM UTC-10, . wrote:
> On 9/21/2017 12:00 PM, dsi1 wrote:
> > On Wednesday, September 20, 2017 at 1:25:51 AM UTC-10, micky wrote:
> >> "Do not remove the thermostat in
> >> the engine cooling system as this
> >> may cause the engine to overheat.
> >> The thermostat is designed to con-
> >> trol the flow of coolant to keep the
> >> temperature of the engine within
> >> the specified operating range"
> >>
> >> From a Toyota manual. I thought removing the thermostat could cause
> >> the engine to underheat, never reach proper operating temperature.
> >>
> >> Do I know more about this than Toyota?
> >
> > My guess is that you don't know more about this than Toyota. If you use a regular type thermostat on a system that requires a bypass type thermostat, part of the coolant is going to bypass the radiator. How much coolant is going to bypass the radiator? I don't know but my guess is that the coolant is going to flow in the path of least resistance and that path is probably not through the radiator.
>
> No, the bypass system is of smaller cross sectional
> area and more restrictive than that of the normal
> path to and through the radiator.
>
> > If your engine overheats and the cooling system appears to be working properly, it would be a good idea to check if you're using the correct thermostat.

It sounds like you're saying that the path through the engine block is more restrictive than the path through the radiator and the engine block. How does that work?