I always wondered why thermostats and their plumbing are now arranged the way they are.

Jim

On Jan 25, 2013, at 8:40 PM, Scott Daniel - Turbovans <scottdaniel@TURBOVANS.COM> wrote:

> Being Friday ..
> early 122's still had it I believe.. ( and 444's and 544's before that  )
> but certainly no 140 series or later volvo's.
> 
> 
> re "I don't think automotive thermostat technology has changed much if
> at all since the fifties. "
> 
> There are two significant advances in thermostat technolgoy since the 50's..
> One is a 'two door' ..
> or two pathway thermostat.
> All waterboxer and diesel vanagons use this type of t-stat.
> When one circuit is closed ( like the main-to-radiator circuit ) when
> things are cold,
> a 'bypass circuit' is open ..
> allowing coolant to flow around and around in the engine , but not
> through the radiator circuit.
> 
> as things warm up, the bypass circuit closes off, and the main circuit
> opens.
> the two 'doors' are on a common shaft..
> so one opens while the other closes.
> 
> the other advance is having the thermostat on the bottom or 'return'
> side of the engine.
> VW diesel engines are arranged that way.
> so are subaru engines ...
> just improves temp stabiilty is my understanding.
> 
> and ....there may already be a few cars with the t-stat controlled by
> the ECU.
> 
> scott
> turbovans
> 
> 
> 
> On 1/25/2013 5:55 PM, JRodgers wrote:
>> Early Volvos - the 544 series and some later - had a wind block built
>> into the vehicle so that from inside the car you could raise and lower
>> the wind block to deal with extreme cold air across the radiator and
>> through to the engine. Not sure when they dropped it on cars coming into
>> the US.
>> 
>> John R
>> 
>> On 1/25/2013 2:37 PM, Dave Mcneely wrote:
>>> Jack, actually, you did post to the group.  Your description of the
>>> thermostat being able to modulate, and open just the right amount?
>>> Whenever I've tested one in a pot of water on a stove, it opened
>>> fully as the water heated, but as it cooled, it closed slowly, as if
>>> it might be doing as you suggested.  Maybe I got it too hot too fast
>>> for that phenomenon to fully reveal itself on the way up, but the
>>> cool down was more gradual.
>>> 
>>> But, I have had the experience of very low temperatures and high
>>> speeds keeping the temperature down on more than one vehicle. My
>>> father's '53 Chevy had to have a wind block whenever the temperature
>>> was below about 10 F.  My camper benefits if the temperature is
>>> around 0 F or colder, when driven at highway speed but is ok without
>>> it at town speeds.
>>> Just my 2 cents, and probably worth what you paid me.
>>> 
>>> mcneely
>>> 
>>> ---- Rocket J Squirrel <camping.elliott@GMAIL.COM> wrote:
>>>> Hi Scott -- before I pester the group with a question that might be
>>>> common knowlege, I figure I could pester you with it first?
>>>> 
>>>> People write about putting cardboard in front of the radiator. I think,
>>>> "I don't get it. The thermostat isn't an on-off switch, doesn't it open
>>>> just as much as needed to keep the coolant at the right temperature? If
>>>> the coolant coming back from the radiator is darn cold, won't the
>>>> thermostat just crack open a bit?"
>>>> 
>>>> Or maybe it does a poor job regulating temperature when it has to do
>>>> that "crack open a little bit" thing.
>>>> 
>>>> --
>>>> Jack "Rocket j Squirrel" Elliott
>>>> 1984 Westfalia, auto trans,
>>>> Bend, Ore.
>>> 
>>> --
>>> David McNeely
>>