Overheating and mitigation methods

[Motortrend]

PV=nRT you know

Yeah, if you know, you know.

[dr. d]

P1v1/t1 = p2v2/t2 .

[Dr.Kamiya]

Cooling system is sealed so atmospheric pressure shouldn't be affecting internal pressure.

But the ambient air itself will be less dense and will have a reduced cooling effect.

F1 at high altitude tracks more cars overheat (just like Baguio).

[Motortrend]

Cooling system is sealed so atmospheric pressure shouldn't be affecting internal pressure.

But the ambient air itself will be less dense and will have a reduced cooling effect.

F1 at high altitude tracks more cars overheat (just like Baguio).

Engines also work harder, right?

[oj88]

Cooling system is sealed so atmospheric pressure shouldn't be affecting internal pressure.

Not fully sealed.

The coolant pressure cap keeps the pressure inside the system at a set pressure above atmospheric pressure. So if you lower the atmospheric pressure, the valve will release the excess until it equalizes again to the set cap pressure above atmospheric pressure. Hence, the cooling system will run at a lower pressure at high elevations.

But the ambient air itself will be less dense and will have a reduced cooling effect.

Agree. The radiator will not be able to shed as much heat due to less air molecules to transfer to.

As a side note, you will see in many equipment like electronics (ie. servers, IT equipment, some consumer electronics, etc.) wherein the specs may have a stipulation about the maximum altitude the said equipment can be safely operated. It's because of the less dense air at altitude, which can interfere with the equipments' own cooling capabilities.

Case in point, most projectors has an on-screen setting wherein you can set it to Normal or High-altitude mode. The main difference is, in Normal mode, the fans operate at various speeds and would likely spin at low speed to reduce noise. But once the projector gets hot enough, the fans ramp up to high speed. But in High-altitude mode, the fans are always at high speed to compensate for the thinner air.

[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.

[Mask Rider Blac]

I received this email from Fleetguard
Understanding coolant and recommendations
I think this webinar is not exactly for cars, but I guess, (liquid) cooling systems are similar naman for most types of engines.

Understanding Coolant and recommendations - Album on Imgur

Webinar Registration - Zoom