how hot is too hot?

[94ram1500]

thats a huge engine, it may be that's normal for that beast compared to a 5.9, I know guys that occasionally hit 220 pulling a load on an upgrade with the 5.9. never hurt it, and my charger with a 440 would hit that with cruising town in summer

 

[crazzywolfie]

that is where running a 180*thermostat is a bit nicer. i generally see 190-195 in my 81 with a 180* thermostat. it helps keep the engine cooler especially if used in combination with electric fans. electric fans can be set to come on at whatever temp you like. if you are worried about engine temp you could always run a aftermarket gauge. most are pretty compatible with the stock sending unit that is in your 94. i installed a temp gauge in my 93 and ended up just disconnecting the stock gauge and running the sensor wire to the aftermarket gauge and it seems like it was accurate

Also if your heater core is laking could mean less coolant in system than is needed, causing slight overheating.

you usually have to loose quite a bit of coolant before seeing abnormal temp gauge movement. i know i got a lot of experience with coolant leaks and running low on coolant. drove my 81 11 miles with absolutely no coolant at all in the system

 

[94ram1500]

220 was in the normal range for my 70 charger, engineers tested the cooling system in the California dessert, no damage. at 230 you still have about 30 degrees till it will boil over and cause damage. I wouldn't worry about it. btw as far as adding cooling chemicals to the radiator, they work, water wetter is good and i thinks it was engine ice worked great. I leave the truck running with the ac blasting when I bring the dog to town, and it brought it down 15 degrees. 215 to 200.

 

[crazzywolfie]

in my opinion 220 is too high on any vehicle with a proper working cooling system. anything over 205 and there is likely something wrong with the cooling system in my opinion. i have never seen my temp gauge go past 200 even going up a steep hill on a hot day.

 

[El Huapo]

I know this late but I have bought coolant thermostats that didn't work properly right out of the box. I now take any new thermostat and put it in a pot of water heating on the stove with a thermometer and watch when it begins to open. After I know it's working at the correct temperature, I will do the work to put it into my engine. Just sayin'...
As for totally bypassing the radiator transmission cooling feature, it might be OK where the ambient temps don't get very cold, but it's a hydraulic system and they don't work very well if the fluid is very cold. So a good separate trans cooler is great but keep the lines going through the regular radiator so on cold days it will warm up some from the engine coolant. A really trick setup is a thermostatically controlled bypass valve to cut out the radiator effect after a certain temperature is reached---used to be used ages ago in racing applications, don't know if parts are still available. Happy trails.