[alfa] Re: more on '77 spider cooling problem

["Dean W. Cains" <dwc@xxxxxx>]

Hi Chris:

I'm going to assume a some things;  you've got the fan wired to blow in the 
right direction, you've got the fan switch set to an appropriate temp, your 
temp gauge is close to being correct, the fan belt is tight, you didn't use 
to much anti-freeze, and even that your cooling system is in good shape 
internally.  Having said that, I can tell you the only circumstance I've 
seen in which a properly-installed electric fan simply wouldn't work.  Bear 
in mind that I'm in S. Florida, so this is a very appropriate test 
environment for any cooling system.

I had the exact same fan setup on both my '74 & '87 Spider's, but the 
system wouldn't work on the '87.  The only difference was that the '74 had 
a newly-recored 2-row radiator, while the '87 had an almost-new OEM 
(non-recored) radiator.  The recore has lots of void space for airflow 
between the vertical coolant tubes, with zig-zag fins running between each 
pair of tubes.  The OEM has full-width horizontal fins, which have holes 
punched in them, through which the vertical cooling tubes run.  Hold the 
recore up to the sun, and you'll wish you had your shades on, but almost no 
light shows through the OEM.  Same goes for airflow.  I could feel a strong 
breeze flowing through the recore when the pusher fan was energized, barely 
a wisp on the recore.  Any electric fan that will fit a Spider (I use the 
12" Permacool units), compared to the OEM belt-driven fan, is very weak by 
comparison.

I've attached a pic of an OEM radiator, and you'll see what I mean about 
all the fins.  There are actually more than 20 horizontal fins per vertical 
inch.  That makes for a huge amount of surface area, which works great with 
the high-volume OEM fan, but he electric just wouldn't cut it.  The core is 
so dense that even a direct stream of water from a hose just barely 
dribbles through it, so you can guess what happens to air flow pushed 
through it.  If your radiator looks different, it's a recore.

I wanted the electric fan badly enough to almost have the OEM radiator 
recored with a 3-row core, but just couldn't bear to cut up something that 
expensive that was in perfect shape.  I'm waiting to see a trashed radiator 
on eBay, to recore, and then I'll reinstall the electric setup on the 
'87.  For now, all the OEM stuff is back in place on the '87 and working to 
spec, as is the electric setup on the '74.

So, how much of that do you think applies to your situation?

Regards,

Dean
Lutz, FL
'74 & '87 Spider Veloce's


At 11:46 AM 9/22/2003, you wrote:
>Date: Sun, 21 Sep 2003 17:07:22 -0400
>From: "Christopher Keen" <ckeen74@domain.elided>
>Subject: [alfa] more on '77 spider cooling problem
>
>Hi again,
>Thanks to those who already responded - I've got a couple more data points
>that might help toward the solution:
>1) I tested the coolant temp. sender today in a measuring cup full of hot
>water, and compared the gauge readings to those on a meat thermometer stuck
>in the measuring cup. I could never get the temp. gauge to read above
>160-ish, even though the meat thermometer read 180-200 degrees (the
>improvised ground wire I used was pretty thin, could that cause this?). So I
>can probably assume that the gauge is not reading higher than actual values.
>2) On another note, the gauge seems to be affected by acceleration,
>cornering, etc., reading slightly higher or lower depending on if the car is
>accelerating, braking, or turning left or right - but overall it still reads
>higher than it used to.
>3) This problem showed up right after I installed the electric fan. The car
>ran a steady 180 almost all the time, except on hot days, when it might have
>gone as far as 190. I haven't replaced any parts on the cooling system since
>then, and there are no leaks.  Now the temperature creeps up above 212, at
>which point I chicken out and stop to let it cool off.
>4) This problem appears under heavy load or in slow traffic. Yesterday it
>showed up while I was driving up a curvy road over the coastal hills. The
>only time under heavy load that it doesn't show up is when I am driving on
>the freeway, at which point I assume enough wind is blowing through, fan or
>not, that the engine stays cool.
>As always, any suggestions are appreciated. I'm guessing my next step is to
>have the radiator serviced.
>Thanks
>Chris Keen
>'77 spider
>Los Altos, CA

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