Date:         Mon, 3 Aug 1998 18:40:12 -0700
Reply-To:     Ari Ollikainen <Ari@OLTECO.COM>
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Ari Ollikainen <Ari@OLTECO.COM>
Subject:      How hot is HOT?
Comments: To: vanagon@vanagon.com
Content-Type: text/plain; charset="us-ascii"

        It hit 100+ in my neighborhood today AND my HIGH-speed radiator fan
        cycled on while running the AC and idling my 90/91 camper, waiting in
        line to pick up my daughter from summer day camp. The temp gauge
        needle NEVER got more than a needle width toward HOT beyond the LED.
        This prompted me to think about what constitutes OVERheating versus
        just normal operation in HOT ambient conditions. I found some
        interesting numbers in Bentley:

        Thermostat begins opening at 85C/185F; fully open at ~ 105C/221F

        Thermoswitch for radiator fan     Stage I       Stage II   Stage III

        Cut-in temp                       89C-94C       95C-100C    ??
                                         192F-201F      203F-212F

        Cut-out temp                        81C            87C      ??
                                           178F           189F

        So...as long as the waterpump circulates coolant AND the faster
        radiator fan cycles on and off, the cooling system is health and
        doing its job?

        If the cut-out temp for the thermoswitch for stage I is below
        thermostat opening temp, this means that the thermostat closes
        to keep the engine within normal OPERATING temperature? (DOH!)
        Similarly, for stage II, the RRRRRRRR speed has to cool the
        circulating coolant down to 189F before cutting off the fan, which
        means, again that the thermostat would now be partially closed to
        keep the engine within the normal temperature range...which would
        tend to explain why there are no wild fluctuations of the needle
        in my temp gauge when this is happening since the tempgauge sender
        is on the engine side of the thermostat and thus in the "internal"
        coolant circulation loop...Typically the needle reaches a needle width
        beyond the LED when the either fan speed cuts in. It's still
        thereabouts when either fan speed cuts out. Is this normal?







      OLTECO                         Ari Ollikainen
      P.O. BOX 3688                  Networking Technology and Architecture
      Stanford, CA                   Ari@OLTECO.com
      94309-3688                     415.517.3519