Turn that engine off when temps are high - and then watch the temperature really climb!
That hunk of iron stores an amazing amount of heat. At that point I found it best to let the cooling system try to do its job without a load on the engine - i.e. A/C off, revs to ~1200, perhaps a spray of water in front of the truck for a little bit of evaporative cooling.
As for the original question, I'm starting to get concerned when temps in the '93 go above 210 and
stay there. This is not to doubt the wisdom of Toyota engineers; it is because that truck doesn't normally do that.
Yes, absolutely. I should have been more specific... to me, "STOP" in an overheating system means shut off AC, pull over and switch to neutral, open hood... anything you can do to reduce strain on the engine and get it to cool. If that doesn't work and it continues to climb... well, it's going to shut off one way or another sooner or later!
Probably some other thoughts worth mentioning. If you're just driving along in relatively normal weather and your temps just shoot up like a rocket, you've probably got some sort of serious and immediate failure with your cooling system... should go without saying that your system isn't going to cool if it's dumping all your coolant on the ground.
It also depends on what's happening... am I driving on an extended road trip? Or am I doing a normal commute that includes a couple of steep hills? Or am I stuck in a traffic jam? Or wheeling? If I know my loads are going to decrease significantly just as soon as I peak this hill, I'll push it a lot higher than I would in the "family road trip" scenario. If I'm crossing Death Valley, I'll probably be keeping an eye on it anyway. Incidentally, I did that in an Isuzu Trooper with family when I was a kid and I honestly had no idea how hot it was outside until we stopped. Getting out of the AC was like getting punched in the chest!
@jonheld No disrespect intended, but I don't entirely agree with your analysis of the cooling system capacity: the coolant and the load aren't the whole equation. Airflow is also a major factor. 203* at a standstill is very different from 203* moving. Also, the thermostat is fully open at 203, but is your clutch fan pushing maximum air at that point? Sure, if
nothing else changes, then theoretically the temps would continue to climb. To my mind, the odds are on some other factor changing before you're in truly dangerous territory, or as you said, you can change a variable or two yourself (slow down, etc). What I'm trying to get a handle on is what is considered truly dangerous. If you are saying you aren't at all comfortable pushing it past 203, then fair enough.
