Someone wrote that he'd watched the cylinder head temp on an AC van and
saw a drop in temps when drafting.
  Extrapolating to a water-pumper Van, it should drop also.  If indeed you
are using 30% less power to maintain your speed while in the draft...Cooling
should not be a problem..If you can grind up a very steep pass with a fully
loaded van at 25mph without overheating, loafing along at 1/2 throttle in
The Draft probably won't cause any overheating.  I don't know this for sure
because I rarely draft a semi...I prefer to pass them and not deal with all
the buffeting I feel when I am in their draft...I used to follow one for
miles when I drove a splitty bus...because that would take me to a higher
speed than I could manage alone..

  The 3-second rule?  Following at a safe distance?  You ever drive a
freeway in So. Cal?  Crap, those folks rip along at 85+ within a few feet of
the car ahead..If you leave even close to one car length some one will try
to squeeze into that hole ahead of you.  All the while, talking or texting,
putting on makeup, drinking a Latte, or driving a huge over loaded truck
with 6 more lanes of traffic going the same speed...Makes drafting a semi
out on the highways seem like a child's pre-nap relaxation game..If you dare
drive at a mere 70mph...they give you "The Stink-Eye" as they speed past...
  Don Hanson

On Wed, Aug 26, 2009 at 1:17 PM, Marc Perdue <mcperdue@gmail.com> wrote:

> Given that drafting is dangerous, given that Mike S. probably wasn't
> implying drafting, the question remains, does drafting affect the
> cooling system significantly on a water-cooled vehicle?  Additional
> question, assuming you are not drafting but following at a safe
> distance (3 second rule), would you be outside of the lower pressure
> zone behind the truck in front of you?  Just curious...
>
> Marc
>
>
>