You can get a better fan.  You can travel 100 mph (the air goes
through the rad at the speed you travel.

I had a truck with a 2 core rad and a three blade fan.  Replaced the
fan and the thermostat but the telling day was when it rained and then
stopped raining and I noticed a significant cooling effect with the
cool rain on the rad.
A three core rad fixed the problem for me.
We were towing and the small rad wouldn't cut it.  By the way, there
isn't a fan on God's green earth that can suck air faster than the
truck surging through the air at highway speeds.  Stop & go, yes,
highway NEVER.
-
Regards
Gordie

Yes I agree with what you are saying but I don't recal anywhere in the
OEM (GM) manuals where it talks about "adjusting" the fan clutch. At
least I've never seen that documented, outside of your web site. I'm
not saying you can't do it, I am saying that it  is general practice
to assume tha the fan clutch is either a pass or fail item, it either
works properly or it needs replacement.

The regular radiator on a 1/2 ton of that year model is a piece of
crap, and I'm guessing on the 3/4 tons too. The one I had was some 28
inches wide....compared to something like 34 inches wide for the heavy
duty models which require a different shroud.

If you want to stay with OEM products and you verfity operation of the
fan clutch and the cooling in inadaquate....if the shroud is fully
operational and not cracked and the water pump is working..... you
only really have one other items to look at, considering that the
engine has no mechanical issues.

Its also woth nothing that the 34 inch wide model radiators are also
thicker than the 28 inch wide modles. So in the end game you look for
a radiator that presents the most surface area and has the laregest
capactiy that your vehicle supports. Its obvious that on these
vehciles from the 1/2 ton to the 3/4 ton and maybe even the 1 ton
truck that they share the same front end, same radiator support and
generally the same radiators and cooling system depending on the
engine size and if it has HD cooling.

They only make one OEM fan for those year model trucks and the fan
clutchs are designated by the rear end gearing (GM). So if you can't
increase air flow you look to a larger capacity radiator or sometimes
a more efficient radiator given a fixed surface area..

In my case I went with a large capacity / effecient aftermarket
radiator that is roughly the same diminisons as the HD cooling model
for the 3/4 ton truck. IN order to do so I had to change the shroud
and also add the two top radiator mounts like the 3/4 trucks of that
year have. Upon observation of a friends turck I did change the fan
shroud to one like a 98 year model 1/2 ton because like i said
previously it allows for a wider and thicker radiator install.

Of course its a given that if your truck is a 3/4 ton and came with HD
cooling you most likely have all this in place to start with. But I'm
guessing that some of the 3/4 tons with 350 engines had the crappy
light duty 28 inch wide radiator, just like what was on my 1/2 ton.

I also think during this time some of the trucks had oil coolers built
in the radiators while others did not, which I'm sure adds to the
cooling issues.  

I do think that the cooling on some of these trucks is marginal
especially if you find yourself off road in 4 wheel drive where you
have a situation of (hot summer days) low rpms and thus low air flow
across the radiator. Situations where you are forced into moving slow.
The truck is moving slow, the rpms are low and the temp is hot.  A lot
of these trucks run right around 210 all day long and you stress them
much and they certainly will get aboove 210.  SOmething parallel to
heavy traffic on a hot summer day where you have a lot of idle time
and repeated stop and go situaions.  You can stress one oout on the
hilly or mountionious areas too, given a heavy load and repeated stops
up an extended grade (even on the pavement).

THe problems I've observed were most of the time situations where the
truck did not or was not able to pull a sufficient amount of air
across the radiator, due to the various situations you coud find
yourself at extended idle time right in parallel with heavy loads on
the engine.

I'm not talking about everyday driving on the interstate, or driving
across town in light traffic.

I think even GM made note of this issue when they had some of these
trucks with a auxillary  electric radiator fan that was mounted on the
front of the passenger side radiator and would come on and blow air
across the passenger side radiator when I think the temp rose aboove
approx 200. It may have come on in parallel with the A/C operation
too?
-----------
Elbert
ask@me.com