Re: RE: DO NOT change t-stat...(Jules, help!)

From: Jon Steiger (
Date: Wed Jun 03 1998 - 01:27:28 EDT

At 11:11 PM 6/2/98 -0500, you wrote:
>Here is my 2 cents worth. I don't remember where I read this, but here
>it goes:
>When you change the thermostat to a lower temperature, you risk the
>possibility of overheating. I know, it is hard to believe. The
>explaination starts with temperature differental between ambient air and
>water temperature. The higher the differential between ambient air
>temperature and watter temperature, the more heat transfered from the
>coolant to the air. By lowering your coolant temperature to 180, you
>are lowering the temperature differential by 15 degrees. This means you
>have to make up that 15 degrees in heat transfer somewhere else.
>I'm no expert, this is from a magazine I read.

  That's an interesting point; I hadn't thought of that. Makes sense
too. The greater the differential, be it temperature, pressure, whatever,
the greater or faster the transfer, as mother nature tries to reach that
elusive equilibrium.

  I'm no expert either, but here's my take on this:

  While "greater differential = more transfer" is true, I don't
think it works out that way in a "real world" situation. (Well, in our
particular application that is, because there are other variables involved.)
   Whenever there is a differential, no matter how slight, a transfer will
take place. As the differential approaches zero, so does the transfer, but
until it does, some transfer happens. Apparently, the transfer that does
happen is great enough so that the engine stays happy. Even on a really,
really hot day (120 degrees F), there is still a 60 degree differential.
For most normal driving, the differential is probably 100 degrees or more.

  Another thing that comes into play: Although the transfer is probably
not as fast with a cooler thermostat, there is also less heat TO transfer!
  It would seem that the cooler thermostat more than cancels out this
"transfer loss".

  Speaking strictly from experience, the temperature guage on my truck
reads noticibly cooler compared to when I had the stock 195 thermostat
installed. I also know that it is keeping my engine cooler because
it eliminated the pinging that was brought on by the advanced timing
curve of the MP computer.


  .--- -- ---.
  | DoD# 1038, EAA# 518210, NMA# 117376, USUA# A46209, KotWitDoDFAQ, RP-SEL |
  | '96 Dodge Dakota v8 SLT Club Cab, '96 Kolb FireFly 447 (#FF019) |
   I do not speak for the SUNY College at Fredonia; any opinions are my own.

This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:08:54 EDT