Now THIS subject, I know something about...
There are a number of things you can do to make your 94 run nice and cool with that load... the short list looks like this:
a) pull and clean rad (and coolers) thoroughly
b) check your thermostats (since you already changed to a 2-tstat system)
c) replace your fan clutch and possibly your fan
d) proper water/glycol mix and a couple bottles of water-wetter
e) TCC Lock mod
Want the 3-step details on any of these?
Rad Clean
Start on a Saturday morning... it will take about 3-4 hr to do this right.
Buy:
- new hose clamps
- GENUINE AC Delco thermostat (for single t-stat systems this is a must)
- Heath SD Fan Clutch
- 2 bottles RedLine Water Wetter
- 2 gallons of Top quality Antifreeze/Coolant
- 1 bottle of 'scrubbing bubbles' bathroom cleaner.
Set up shop in the driveway or someplace where you can clean the rad, then get the hose and wash away all the crap you get out of it... bugs, sand, little rocks, leaves, dandelion fluff, slow hitch-hikers, politicians, etc.
1] definitely pull your rad and clean it properly. Yes, it has to come all the way out. No, it isn't that big of a deal.
- drain rad - 5 min
- pull shroud - 5 min
- undo clamps, hoses, rad lines - 5 min
- pull grille (top bolts, front clips, a couple screws behind signal lights) - 15 min
- lift out the rad, place it face-down on a couple of sawhorses or 5-gallon plastic pails, and start washing it out from back to front... use a sprayer on a garden hose (you can bend stuff with a pressure washer), spray it clean then spray it with foamy cleaner (I like 'scrubbing bubbles bathroom cleaner), let it soak 15 min while you clean the AC, Tranny, oil coolers. Go back and wash it all out again.
Twice. Use a leaf-blower or compressed air (Carefully!) to blow out the sand, dirt, little rocks, etc.. when it is shiny-clean, it's ready to go back in.
These things hold an AMAZING amount of crap... this is going to make a serious mess, so if you can do it someplace where you can just spray away the crap you get out of the fins when you're done, you can stay out of trouble with the little woman. Plan ahead, and don't start the job out on the patio or someplace like that. I like to use my neighbor's driveway.
2] check the fan clutch. If it is stock and especially if you've never heard it (it sounds like a jet engine taking off under your hood when your truck gets hot while towing), it probably needs to be changed... yes, they DO wear out.
Here is a description of the different fan clutches... you want one that is either HD or SD. Get one that is calibrated to kick in a little sooner than 210 (Heath's is calibrated to kick in 10-15 degrees sooner, and is a high torque-transfer clutch, which means when your engine is doing 2000 rpm, your fan will be doing a large % of that... not so with all clutches ... ask if this statement is confusing and I'll explain further). Note that they kick in at a pre-set AIR TEMP, not water temp. The air temp is usually about 10* lower than your rad water temp, so if it says it kicks in at 190-195*, that means about 200-205* water temp. You want it to kick in BEFORE you overheat, not after.
Think about changing your fan.. the 94 6-blade metal fan can be replaced by a 2000 9-blade metal fan, or a 9-blade composite DMax fan, both of which move considerably more air.
3] replace the thermostat. Make sure you use a GENUINE AC Delco thermostat... (for a single T-Stat system, there is no other acceptable brand... there is a plunger-bypass needed, and they must be high-flow. You ignore this advice at your own peril.) For a 2-tstat system, RobertShaw makes good thermostats, too.
- do it all back up, replace the crappy GM hose clamps with the new ones you bought, pour in 2 bottles of Redline Water-wetter and fill with 50% antifreeze mix. Burp system as required.
TCC Lock Mod
You're lucky... since you have an OBD-I system, you can put your Torque-Converter on a switch to force it to lock up, which will make your transmission run a LOT cooler when towing, and has the added benefits of giving you engine braking in the hills. That's a topic for another thread, but if you're interested, let me know and I'll write something up.
Before doing all this to mine, I overheated on a sunny day in January. Since this, I pull my 30' fifth wheel through the mountains in BIG ambient heats with the AC on... Don't let anybody tell you it can't be done without spending whacks of cash replacing stuff.
But don't let anybody tell you that you don't need to pull the rad, either... do it right, or do it over.
That's my story, and I'm sticking to it.
Jim
