Re: [alfa] alfa cooling saga

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

Hi Chris:

I know it may be distressing to see the coolant temp above 180F, and 
especially at 212F, but it's really not a problem.  Granted, there's not as 
much reserve cooling capacity as original, due to the new fan blocking some 
airflow from the front of the radiator, and simply never moving as much air 
as the original fan.  But, 212F on a hot day in traffic, with a properly 
filled, bled, and pressurized cooling system isn't anything to worry 
about.  I live in S. Florida, have an electric "pusher" fan on my '74 
Spider, and have seen my car behave exactly like yours for the past several 
years (since the fan conversion).  So far, no troubles to report or any 
incidences of overheating.  A pressurized system won't boil until it gets 
in the neighborhood of ~250F, so even in traffic, you've still got about 
40F of safety margin.  It's the pressure, much more than the anti-freeze 
that's responsible for that.  FWIW, just like yours, the temp needle on my 
Spider never saw the far side of 185F with the original radiator fan.

If you want to play with a few minor details, here are a few.  Try reducing 
the percentage of anti-freeze from the typical 50% to around 20%.  The Alfa 
factory manuals actually recommend this for summer driving, although more 
likely because older coolants needed to be changed more often, and maybe 
they were thinking you'd be changing it fall and spring.  The fact is that 
water is a much better conductor of heat than the higher percentage mixture 
is, so you'll get better cooling with 20% anti-freeze.  You won't be giving 
up anything in corrosion protection if you use de-ionized or distilled 
water and a premium anti-freeze, like Dex-Cool.  Second, the temp sensor 
for the fan really should be in the bottom radiator tank.  What you want to 
measure is the temp of the coolant after the radiator has had its chance to 
cool it with the available airflow.  A sensor in the top tank may cause the 
fan to be on too often, if not all the time, or depending on how you set 
it, may be a little late in the loop.

Other than that, IMO, your Spider's behaving just fine.

Regards,

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


At 03:56 PM 8/9/2004, you wrote:

> Date: Sun, 08 Aug 2004 21:52:33 -0700
> From: "Christopher Keen" <ckeen74@domain.elided>
> Subject: [alfa] alfa cooling saga
>
> Hi all,
>
> Thanks for the brake advice a few weeks back - all those upgraded pads
> turned out to be rather pricey given my current underemployed status, so I
> went with stock stuff.
>
> But what's still bugging me is the cooling issue with my '77 spider. I had
> replaced the engine-driven fan with an electric one a couple of years back
> and then gone off to grad school. Since then, the car tended to reach temps
> of 190-212 in traffic where before it always ran at 185, except on very hot
> days after a long run on the freeway, where it got up to maybe 195.
>
> When I got back from grad school last fall, I started working on the
> problem. I've now got a new 3-row core in my radiator, new water pump belt,
> new Alfa OEM thermostat, bypass restrictor, and I've tried moving the
> thermo-probe to the top of the radiator (temp difference betw. top and
> bottom was about 50 degrees - 180 vs 130, roughly). I also tested the temp.
> sensor that is connected to the gauge, and it's more or less accurate.
> Timing is set to 34 degrees BTDC. The heater is really effective, which
> suggests to me that the system is properly bled. Today was the final
> recommendation I took from the helpful emails everyone sent, which was to
> move the fan to the engine side of the radiator. However, the fan mounted on
> that side of the radiator won't clear the water pump, so that didn't work
> out so well.
>
> So, does anyone see that I'm missing something here? I'm really reluctant to
> go back to the engine driven fan since I've had enough radiators chewed up,
> and what's more is I like the extra space underhood as well as the reduced
> noise - I can hear more engine and less fan, which is a good thing in any
> Alfa.
>
> Any suggestions would be appreciated, even if they're all in caps :P
>
> Thanks,
> Chris Keen
> '77 spider
> Los Altos, CA
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