[V8] Re: cold weather killing gas mileage (AHA!!!)

[Ingo Rautenberg]

Well, I'm pretty sure I did.  I know the ball-relief valve is at the top.  I
did install it the same way as the old one and wasn't sure that it could be
reversed, but will check when I inspect again.  Hmmm....

----- Original Message ----- 
From: <dsaad at icehouse.net>
To: <v8 at audifans.com>
Sent: Monday, May 02, 2005 10:21 AM
Subject: Re: [V8] Re: cold weather killing gas mileage (AHA!!!)


> I does not take much of a leak around the thermostat to really kill
mileage in
> sub-freezing weather. If you think about it a little, the cooling system
in
> effect is trying to keep the radiator at 97C (its a side effect of keeping
the
> motor at 97C). It can't of course so if you have a slow or sticky t-stat,
it
> will shut untill the motor heats up - then it opens too much - letting in
a
> deluge of really cold water. The thermal shock alone is not good, and the
ECU
> will dutifully notice the operating temp is too cold and put you back in
cold
> enrichment mode. If you can see the needle swing back and forth then you
have
> something like this going on.
>
> This is one reason there is a tiny bypass hole in the thermostat. It will
allow
> some cold water to pass - hopefully keeping the t-stat more closed when it
is
> cold, and prevent the wild swing.
>
> That brings up a point - did your new t-stat have the by-pass valve? (the
little
> steel ball in a cage) and is it installed properly? You can often install
the
> t-stat backwards if you are not careful.
>
> Dave
>
>
> Quoting Ingo Rautenberg <i.rautenberg at waratap.com>:
>
> > You guys have me thinking.  This morning I watched my temp gauge and at
42°F
> > it took (mixed city/hwy) over 20 minutes to get to operating temp.  Over
> > twice as long as I would think.  And thermostat  was replaced less than
20k
> > ago...
> >
> > Ingo
> >
> >
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