Why do trucks fail on an uphill climb?

I ran one of these in the 80's, all 48. Aerodynamics of a brick and had no problems with over heating.

 

Back in the day of needle nose butterfly hooded trucks that only had 1050 sq in. of radiator pulling over on the top of a big grade in the rockies to let ‘er cool down was common. My uncle used to un latch the hoods pull them out a bit and set them on the headlight housings while running the range up to his Montana ranch many many times. The old truck still has them scars etched in the aluminum.

 

Higher RPM = Lower EGTs, fan locked on the whole way. Monitor oil/coolant temps.

Pew Al Up

 

Higher RPMs = more coolant circulating also.

 

Uncle used this this old chick to make a weekly run between the two ranches here and in Montana for close to 30 years. 3 million 643k and some change miles. I’m Sure she may have broke down a few times. Lol.

 

And back then we had no cell phones to call for help, just saying.

 

Back then drivers knew how to fix problems in a parking lot .. and weren't Sallys crying about how their shelves rattling or their inverter not being big enough to power their TV and PS 4

 

I'd be willing to bet the farm that @JolliRoger could enlighten us on the pro & cons of the needle nose's and their cooling systems

 

Both of which are indicative of a sad state of affairs in today's big freight carriers.