Re: [alfa] Re: 115 spider cooling system saga

[Steven Moresi <smoresi@xxxxxxx>]

 Charlie, Chris and Digest,

From what I am aware, the purpose of the restrictor in the bypass is to get a bit more flow through the heater core when the car is cold.  If the bypass restrictor isn't there then the path of least resistance is through the larger "bypass" hose not the smaller diameter heater hose.  The restrictor "forces" water to flow through the heater.  'Least that's what I heard somewhere.

Charlie is right - that we buy the correct thermostats for our ALFAs' because they have the bypass block off thingy when the thermostat is open.  This prevents water from just bypassing the radiator when the car is hot (bad!).

Steve
'74 Spider
'64 Spider
  
On Friday, November 14, 2003, at 02:19PM, <C2slayman@domain.elided> wrote:

>Chris,
>    I have close to the same setup on my '89 Spider - upgraded 3 row radiator 
>core, electric fan (actually the Bosch unit used to cool the AC condensor 
>without the condensor in front of the radiator), stock 190C thermostat and the 
>flow restrictor.  This setup stays at 190C without any problems.  On a really 
>hot day, it will creep above 190C by a little, but I attribute that to the 
>inadequacy of the Bosch fan.  It's intended to be a "helper" and not carry the 
>entire cooling load (I've removed my water pump driven fan).  So next summer, I 
>will probably install a "real" electric fan.  But it has been more than adequate 
>for the past year in the Bay Area.
>    I never tried the setup without the flow restrictor.  So I can't say what 
>the performance of my system is with and without.  So your problem might be 
>related to the missing flow restrictor.  (If you get hit by a bolt of 
>lightening, you know it's from Fred up in heaven saying "Put the damn flow restrictor 
>in!")  But the thermostat is 190C, so I'm not sure what you are observing is 
>all that bad.  It might not overheat under hotter ambient conditions.  You might 
>actually be observing the performance of your cooling system in a "thermostat 
>restricted" (ie the thermostat is not fully opened) mode.  If the ambient 
>temperature were to increase and the coolant temperature rises slightly, that 
>might open the thermostat all the way.
>    Rich Hirsch's excellent article at 
>http://www.geocities.com/motorcity/downs/3837/bypassco.html is good reading if you haven't already seen it.  The 
>only thing I'm muddy about is the fact that the thermostat is acutally a "dual 
>mode" design that is supposed to BLOCK the bypass hose in the fully open 
>position (that's why generic thermostats from Grand Auto or Kragen don't really work 
>on Alfas).  So it seems like the function of the restrictor is a little 
>redundant - it regulates the circulation when the thermostat is closed (but who 
>cares since the radiator is not in the loop) and flow to the restrictor is blocked 
>by the thermostat when the thermostat is open.  So I am actually puzzled - 
>unless Alfa designed the flow restrictor before they developed the dual action 
>thermostat and the restrictor was left in as a "prehensile tail".  But I never 
>took mine out for fear of what Fred might do to me if he ever found out!  ;->
>    Hope this helps somewhat.
>Cheers,
>Charlie 
>
>
>Date: Thu, 13 Nov 2003 15:39:50 -0500
>From: "Christopher Keen" <ckeen74@domain.elided>
>Subject: [alfa] 115 spider cooling system saga
>
>Hi all,
>
>So I've done some more work on the cooling system in my spider to solve the 
>hot-running problem:
>
>- - recored the radiator with a 3-row core
>- - new radiator cap (.7 bar)
>- - tested thermostat, it's working correctly
>
>The car is still running hot under heavy load - about 195 degrees, but since 
>its only 65 degrees outside today, I imagine that on a hot day the car would 
>get up to 212ish like it did before. I checked, and the car is missing the 
>bypass restrictor. Do other people with electric fans find the restrictor is 
>necessary to help keep temps down?
>
>For those of you who weren't there from the beginning, I installed an 
>electric fan, and ever since then the car's been running hot under load or 
>on hot days (used to hold a steady 180). The gauge has been tested to be 
>roughly accurate, and the coolant level is full.
>
>Thanks in advance
>
>Chris Keen
>'77 spider
>Los Altos, CA
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Steve Moresi
smoresi@domain.elided
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