I've done a lot of work to be sure their are no problems with the Fan
Clutch, Radiator or Thermostat, yet this 454 with throttle body
injection always runs hot when towing. 240-270 It can get to the red
line and beyond when pulling a steep hill on a hot day. The power is
not good on those days and I don't run with the throttle mashed down.
It runs hot on hot days when not towing also. I'm considering an oil
cooler and would like to do it the right way if I do. I'm looking for
links, advice, other peoples experiences with their projects.
I'm my own mechanic and body man not afraid to tackle a major
change
to the engine or body. Though I'd like to keep this truck fairly
stock
on the outside.
The engine runs very well, though it seems to lack power for a big
block. I will consider an engine overhaul with performance
enhancements if someone can turn me on to the right combination of
ingredients.

<mlemke (AT) key (DOT) net> wrote

On a 20 year old unit, other than the obvious things you've likely checked
like the fan clutch, thermostat function, ECM timing set etc, you have to
consider the possibility that the rad is corroded and deposits are causing
the issues. I would remove and repair/replace the rad if everything else
checks out OK.

On May 20, 10:08*am, "Augustus" <no_... (AT) nowhere (DOT) net> wrote:
2 years ago i put a new core in the radiator that included and extra
layer making the radiator a custom 5 core version. It may have helped
a little. The fan clutch is extra heavy duty making the engine howl.
Though noisier it is somewhat reassuring as the engine does not heat
up on mild days unless towing. I've been told cooling was an issue on
this model year and this is the main reason no 4 or five speed version
was offered in 1989. I'd really like to talk with someone who has
modified something ie, engine oil cooler, electric fans or some
combination of changes to the engine that will make this engine run
strong and cool.

--
http://desertphile.org
Desertphile's Desert Soliloquy. WARNING: view with plenty of water
"Why aren't resurrections from the dead noteworthy?" -- Jim Rutz

mlemke (AT) key (DOT) net wrote:
When was the last time the fuel filter was changed and the fuel system
cleaned? Lack of power and running hot could be caused by an engine
running leaner than it should.

What rear gearing does it have? Higher gearing will make the engine work
harder and hotter.

What exhaust system does it have? A partially blocked converter or
muffler could also cause it to be low an power and run hot.

You already have a larger radiator. Is the fan shroud in place?

Running that hot I would install a heavy duty trans cooler and run
synthetic fluids as well. You could install a rear facing hood scoop to
release the heat from the engine bay. Something like the Z28 style from
the 60's.

Good luck and report back what you find.

--
Steve W.

What type of air intake filter do you have?
Paper, or foam?

On Wed, 20 May 2009 09:25:24 -0700 (PDT), mlemke (AT) key (DOT) net wrote:


Can we assume all the mechanical parts are there and in full working
order... to include the fan shroud and thermostat. I would not run it
past 220F.

Do you have the right fan and fan clutch combination. No-one's
swapped some aftermarket parts in there?

I don't anyone makes a better fan clutch than GM, for a GM vehicle. On
a heavy tow rig....I would not use electric fans as the primary
cooling.

Does the truck have 4.10 gears and are you pulling loads within your
rated range.

Don't know if you get off in the mud but make sure your radiator and
condensor are not full of mud, or crap between the condensor and
radiator blocking the air flow.

No check engine light is on I assume, no reason to expect a head
gasket issue?

What temp does the truck run at unloaded in the summer now?

Have you checked the temp that the computer see's by using a scan tool
to verify that the gauge temp is correct? and that you don't have a
faulty sending unit.

On a tow truck like that...I would want the biggest 4 core radiator
that fits, OEM fan and OEM HD fan clutch, correct thermostat, and
proper gearing at the differentials.

I do think some of those older trucks were known to run fairly hot.

My 01 2500 suburban with 496 runs about 195F unloaded...its rather
new to me, and so far I've not pulled any heavy stuff with it. With
A/C on , idling or running, it never gets over 195 or maybe close to
200. What's your truck doing in present weather conditions..unloaded?

When the truck is warmed up and ambient temp is 80+F outside I assume
you can hear the fan clutch cycle on and off under load? Also when
engine warm and you open the hood you have a nice air flow across
the radiator?
-----------
Elbert
ask (AT) me (DOT) com

On May 20, 6:04*pm, "Steve W." <csr684... (AT) yahoo (DOT) com> wrote:
If Someone has a line on a functional rear facing soop or a tidy way
to vent the hood I'd like to try that. I'm not oppose to modifying the
hood or replacing it with one that is alredy modified.

On May 22, 9:39*am, mle... (AT) key (DOT) net wrote:
First i think I'll put a test tube in place of the cat converter to
see if ther is any good to come from that.

<mlemke (AT) key (DOT) net> wrote

What I had done is make a small plate with a hose barb thru it and mount
that in place of the EGR valve. (gasket too)
Block off the EGR vacuum, and connect the barb to a pressure guage. ( I
have a old Vacuum/Fuel pressure gauge)
Run at different RPMs and check the pressure. A blocked Cat will show
pressure readings, where a clear cat will show next to nothing.
If you have dual Cats then this approach may not work.

Cheers