[DeTomaso] 1972 detomaso pantera cooling system

[David & Marilyn Bell]

The water pump has two intake (suction) ports; the large one (1-1/2") is
cooled water that has just exited the radiator while the smaller (5/8")
comes from the heater core.  Coolant is pulled from those two sources and
pumped into the block where it picks up engine heat.  The heated water exits
the block under pressure at two locations also; the large "L" pipe above the
thermostat is connected to the swirl tank and then to the radiator while the
smaller port sends hot water straight to the heater core.

So, connecting the suction side and pressure side heater core lines allows a
portion of coolant to continually circulate from the water pump to the block
and then straight back to the water pump without ever passing through the
radiator.  That closed loop circulation can be avoided by simply closing
valves ahead of (i.e. - external ball valves) or at the heater core (the
lever on the dash) when additional heat in the cabin is not required.  That
would force all of the heated coolant from the block to pass through the
radiator.


Dave Bell
  -----Original Message-----
  From: boyd casey [mailto:boyd411 at gmail.com]
  Sent: Tuesday, September 07, 2010 8:47 AM
  To: David & Marilyn Bell
  Cc: Asa Jay Laughton; detomaso at realbig.com
  Subject: Re: [DeTomaso] 1972 detomaso pantera cooling system


  I am ignorant as far as the actual path the coolant follows on it's
travels through the car. I was told that the "By pass valve" kept the
coolant icirculation and that just shutting off the flow at the fire wall
actually prevented a portion of the coolant from being circulated. So which
is right? I wouldn't be surprised if the sales person mis represented the
facts to favor his product (the by pass valve) In any case I didn't buy one.
  Boyd


  On Tue, Sep 7, 2010 at 12:52 AM, David & Marilyn Bell
<davidabell at worldnet.att.net> wrote:

    A non-trivial amount of the cooling system's ability to shed heat will
be
    lost if coolant is diverted from the heater core and allowed to freely
    circulate internally.  The diverted fluid (maybe 20% or so of the water
pump
    capacity) traveling in the short-circuited loop never makes it to the
    radiator and so doesn't contribute to cooling off the engine.  The lost
    cooling capacity may not be all that important when the heater would
    normally be on (when it's cold outside), but might be in the summer when
the
    cooling system is much more stressed.

    IMHO, it's much better just to block off the heater ports completely.

    Dave Bell


    -----Original Message-----
    From: detomaso-bounces at realbig.com
    [mailto:detomaso-bounces at realbig.com]On Behalf Of boyd casey
    Sent: Monday, September 06, 2010 9:28 PM
    To: Asa Jay Laughton
    Cc: detomaso at realbig.com
    Subject: Re: [DeTomaso] 1972 detomaso pantera cooling system


    To any one interested Vintage Air makes an electronic servo valve that
    allows you to "by pass the heater core (and cabin) from inside the car
with
    a switch. I don't know if it's fail safe enough for race track safety
    inspectors but it's pretty cool and it dosent just cut of the water flow
it
    allows it to "By Pass" the heater core but continue flowing through the
rest
    of the cooling system so it is not adversely afeected by just cutting
off
    the normal flow pattern.
    Boyd

    On Mon, Sep 6, 2010 at 10:19 PM, Asa Jay Laughton <asajay at asajay.com>
wrote:

    >  Bob,
    >
    > If those are in the heater hose lines, then they are designed to
    > shut-off coolant flow to the heater core.  There are two purposes in
    > this.  First, it reduces interior heat, especially in the summer when
    > you are trying to use the A/C.  Second, some racing bodies want  you
to
    > have shut-offs just in case you blow a heater core or interior line,
it
    > doesn't blow hot coolant all over your feet, windows, etc.
    >
    > Asa Jay
    >
    > Asa Jay Laughton, MSgt, USAFR, Retired
    > &  Shelley Marie
    > Spokane, WA
    > ******************************
    > http://www.racingagainstautism.com
    > http://www.teampanteraracing.com
    >
    >
    > On 9/6/2010 17:55, LEVITT1946 at aol.com wrote:
    > > Dear Group,
    > >
    > > My Pantera has two water shutoff valves in the rear of the car
located
    > > below the coil. Are these valves(1/2") necessary in the Pantera
    > cooling/heating
    > >   system system? What is their function?
    > >
    > > Bob
    > > Team Pantera racing #3196
    > > Gumball3000 #56
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