Overheating and mitigation methods

[Dr.Kamiya]

Yeah you're right about the radiator cap being relative to ambient, but IIRC the boiling point elevation you get from a 1 bar radiator cap plus a 50-50 coolant mix is high enough that the change in elevation shouldn't matter.

Metro manila is currently 1006hPa, Baguio at 853hPa. Boiling point will be just under 100C here, 96C in Baguio -- 4% decrease.
A 1 bar radiator cap raises boiling point to 268F (130C). Applying the same 4% loss (since the percentage pressure delta will be similar) = 124.8C. I don't think a car will be seeing 120+ coolant temps even in Baguio.

AFAIK one of the reasons behind pressurized cooling systems is so that modern cars can perform at altitude -- yes the boiling point is lower, but the cooling system is overdesigned and should handle it (provided of course that it's properly maintained).

[oj88]

provided of course that it's properly maintained.

I think THAT may very well be one of the likely reasons.

It's quite evident that the cooling system is one of those things that are frequently misunderstood or otherwise taken for granted. Especially so if you live primarily in the lowlands like Metro Manila. With the thicker air, the cooling system is quite tolerant up to a certain extent.

But going up to Baguio, it may seem that the combination of the high elevation, sustained uphill climbs, slow-moving traffic, and frequent stop and go, contributes to a hotter than usual engine. Also, many A/Ts/CVTs have a shared cooling/heat exchanger integrated into the radiator. The conditions above would undoubtedly increase the ATF/CVTF temperature which is then dissipated into the radiator as additional thermal energy that needs to be shed.

These conditions combined together makes for an unforgiving cooling system. As such, the coolant type, coolant ratio, coolant level, pressure regulation mechanisms, overall system design, engine health, etc., becomes critical.