Overheating and mitigation methods

**oj88** · June 20th, 2025 01:12 PM

Lately, I've been seeing a number of ads in my Feeds about a certain aftermarket high-CFM auxiliary fan being sold either as an upgrade to the OE aux fans or as a bolt-on to complement vehicles with traditional belt-driven fans. My first reaction was, these fans make a lot of noise and seems overkill.

But then I recalled this video from 2023 about "stalled" cars going to Baguio in bumper-to-bumper traffic (credit to its owner): https://www.facebook.com/share/v/19arRvX9LR/

Based on the video and despite what the owner is saying, it's not perfectly conclusive whether or not every car shown on the side of the road suffered from overheating.... BUT, it does look like it at face value (hood's up, some people tinkering in the vicinity of the radiator, etc.). Whether that's wholly or partly true, I want to hear your take on it.

I've always believed that most modern cars are designed to operate in virtually any conditions. My hypothesis however, is that the high elevation, and hence lower air pressure and density, has a lot to do with it. Less air molecules makes the cooling system struggle to shed heat. So maybe those aftermarket aux fans CAN help under these conditions.

**ice15** · June 20th, 2025 02:20 PM

For modern cars... people forget that coolants have a lifespan and that they need to be replaced.

Same with the fans, a 5 year old fan is not as strong as it used to be.

We have a tita with a 10 year old Vios. And the car has a chance of overheating when the engine is working hard (going uphill - kahit Antipolo lang). All fans are working.

I told her to replace both fans and have the coolant replaced.

After a week... she told me na summer lang naman daw umiinit car nya.

**oj88** · June 20th, 2025 03:10 PM

Originally Posted by ice15

For modern cars... people forget that coolants have a lifespan and that they need to be replaced.

Same with the fans, a 5 year old fan is not as strong as it used to be.

We have a tita with a 10 year old Vios. And the car has a chance of overheating when the engine is working hard (going uphill - kahit Antipolo lang). All fans are working.

I told her to replace both fans and have the coolant replaced.

After a week... she told me na summer lang naman daw umiinit car nya.

I have a digital gauge that measures, among other things, engine coolant temp. 90% of the time, it's pegged at 85°C and the highest it's ever been was 87°C. I imagine that anything higher than 90°C would be something I'd be concerned about.

**baludoy** · June 20th, 2025 06:53 PM

^ Ako I just use the good ole mini elm327 OBD2 scanner. Pero usually sa long drives ko Lang ginagamit.

It's the a/t transmission temp that i pay attention to for some reason.

**dr. d** · June 20th, 2025 09:01 PM

in manila, water boils at 100 degrees centigrade.
in baguio, water boils at 95 degrees centigrade.

**Motortrend** · June 20th, 2025 10:01 PM

Originally Posted by dr. d

in manila, water boils at 100 degrees centigrade.
in baguio, water boils at 95 degrees centigrade.

Because of the cooler climate? I kid, I kid!

**oj88** · June 21st, 2025 09:10 AM

Originally Posted by dr. d

in manila, water boils at 100 degrees centigrade.
in baguio, water boils at 95 degrees centigrade.

That makes sense. Higher elevation has lower atmospheric pressure and even if the cooling system is sealed, will result in a lower absolute pressure... reducing the boiling point of water and/or the coolant.

A coolant mix adds about 25-30°C to the boiling point of water.

You hardly see anyone overheating in the worst Metro Manila traffic (except those with actual engine problems). But then you see all those stalled vehicles heading for Baguio... I love science. :D

**Motortrend** · June 21st, 2025 10:01 AM

Originally Posted by oj88

That makes sense. Higher elevation has lower atmospheric pressure and even if the cooling system is sealed, will result in a lower absolute pressure... reducing the boiling point of water and/or the coolant.

A coolant mix adds about 25-30°C to the boiling point of water.

You hardly see anyone overheating in the worst Metro Manila traffic (except those with actual engine problems). But then you see all those stalled vehicles heading for Baguio... I love science. :D

Yes, because 100 degree boiling point is measured at sea level. What's interesting also is that cooking an egg (hard boiled) in Baguio takes longer than in Manila. Love science, too.

**Yatta** · June 21st, 2025 06:09 PM

Originally Posted by Motortrend

Yes, because 100 degree boiling point is measured at sea level. What's interesting also is that cooking an egg (hard boiled) in Baguio takes longer than in Manila. Love science, too.

PV=nRT you know