Covered radiators

[Jim Grammer <jimg@domain.elided>]

And a merry Christmas to all :)

>Just a note about putting cardboard in front of radiators and stuff.

I just though I'd interject a little YMMV, since I was about to construct a 
message much to this same effect(but not quite)

>Although this is a prevalent idea on the roads today, you will note that
>ALL these systems utilize a covering in front of the grille, NOT the
>radiator.

Actually not quite true in the case of the factory original accessory 
'Shutterstat'. This vacuum(air?) operated shutter was thermostatically 
controlled and sits right in front of the radiator on the installs I've 
seen.

> This forces air to be brought in UNDER the front of the truck,
>so it doesn't blow directly into your engine compartment.  This is why
>heavy trucks use this system, because in actuality it doesn't improve your
>heating system one bit...instead, it prevents the engine fuel
>pump/carburator/fuel lines/etc. from freezing which keeps the truck
>running.

This was going to be my main point. My radiator is 2/3 covered to restrict 
airflow into the engine compartment, nothing to do with the radiator at 
all. It makes a huge difference in how fast the engine compartment warms 
up, and that little Holley 1bbl just does NOT like to be cold. Also, thanks 
to oxy gas I have a pretty regular carb icing problem(until the thing warms 
up completely)in winter if I don't restrict  the airflow. This is in 
coastal CA, mind you, lows in the high 30's(yeah, summer weather for some 
of you ;)), but the  1904's seem prone to it, and the oxy gas is like a 
sponge for water.

>Covering the grille MAY help the heating system a bit simply
>because cold air isn't being directly blown on the heater hose and
>components, thereby preventing a certain amount of scavenged heat loss.
>Placing card board or some other kind of covering DIRECTLY against the
>radiator causes three problems: one is that the radiator will develop
>hotspots, as parts of the rad will heat up dramatically, and others will 
be
>very cold, causing uneven expansion/contraction in an abnormal manner and
>can lead to premature failure...

I guess this is a potential problem, but if there's no flow through the 
radiator anyway(below thermostat temp)it's not really gonna matter. In 
practice for me it has not been a problem in 6 years.

>two, covering the front of the rad prevents
>airflow through the rad, so the fan is forced to work extra hard inside 
its
>shroud creating a vacuum, which robs power and puts extra, abnormal stress
>on the fan and cooling pump components, also causing potential premature
>failure...AND thirdly,  whenever you stop the truck, it gets a chance to
>overheat EVERY time...you might as well have NO rad at all..

I have yet to see a fan shroud on an IH that I though fit tight enough to 
cause a problem ;). Here's a big YMMV. My daily driver(BD-240) will idle 
all day in 100 deg heat and never come above half on the temp gauge(even 
with the radiator block in place). OTOH, the '68 T-all(304, a/c)in the same 
conditions will go straight to the top of the operating range, fully 
pressurize the system and stay there as long as you don't try to run the 
a/c. Both systems are well maintained with recent radiator cores. I think 
the difference is the skinny 6 in that big, tall engine house(B-102)has 
lots of room to 'breathe' vs. the wide V8 stuck in the lower 1100C w/all 
the stuff hanging off it(a/c, p/s).

Also, depending on the truck, it doesn't seem that a drop in gauge temp 
really tells you much about whether a thermostat is installed or not, as 
long as the temp comes back up over time. You could just be seeing the 
system cycling, esp. if the truck is warming up.

Jim