[TR] One last question

[TeriAnn J. Wakeman]

On 9/15/12 10:35 PM, Randall wrote:
>> I just use chevy small block thermostats nowadays.
> Ditto.  Even the factory gave up on those aneroid monstrosities.
>
> -- Randall
>
Are you trying to tell me that the factory stopped putting sleeved 
thermostats in the TR2-4A engine before the TR4A was discontinued???

The TR engine has 2 water paths. One to provide coolant to the head 
while the thermostat is closed and the engine is below operating 
temperature.  This path bypasses the radiator.  The other path is for an 
engine at operating temperature which channels virtually all the coolant 
through the radiator.  That sleeve on the thermostat acts as a valve 
switching between the 2 coolant pathways.

A thermostat without the sleeve leaves both pathways open when the 
engine is at operating temperature allowing coolant to take the path of 
least resistance and bypass the radiator.  What good is the radiator if 
a significant part of the coolant gets circulated through the engine 
without visiting the radiator?

And if you block off the bypass, coolant does not get circulated through 
the head during warm up causing localized boiling and thermal stress 
that often results in a cracked head.

It is my current understanding that Smiths sold new sleeved thermostats 
as replacements for at least 10-15 years after the TR3-4A engine was 
discontinued.

The Land Rover four cylinder engine used a sleeve thermostat as well 
until some time in the mid 1970s.  At that time the LR engineers 
redesigned the thermostat housing to reduce the opening for the bypass 
restricting the radiator bypass flow.  This forced almost all the 
coolant through the radiator when the thermostat is open but allows a 
small flow through the head while the thermostat is closed.

Are the sleeved thermostats " aneroid monstrosities" because you do not 
have one?  over the past 25+ years I've found that they work just fine 
and provide a long service life.

TeriAnn