Heat Wave: Maximum Ambient Operating Temperature for a Vehicle?

[nobb]

With such a massive heat wave coming in, that got me thinking. For an average automobile, what's typically the max safe ambient that most vehicles are designed for? At what coolant temp should one start to be concerned?

I have an OBD monitor and noticed that today when it was +35C out with an idling engine and A/C blasting, that my coolant got up to 100C! It was interesting to see that within a few short minutes coming to a stop, that the temperature creeps up pretty quickly (even though you would likely not notice it because the typical coolant gauge on the instrument panel does not move much). That definitely seemed a bit worry-some as I'm used to seeing 85 - 90C under most circumstances and it's expected to get even hotter this week. In
Curious to see how everyone else's vehicles is dealing with the heat and if you've ever encountered any problems.

 

[A_User55555]

Cars are tested in extreme heat when they are designed. Some manufacturers test drive their cars in Death Valley to see how well they handle the heat.

Generally, cars have no problem withstanding high temperatures. Combustion temperatures can be as high as 4,500F. So 100F heat is nothing for an engine. If you have a newer vehicle, you'll have no issues driving in hot weather.

However, I personally believe hot weather does wear things out faster for older vehicles. Engine bay temperatures are hotter, so old plastic is more prone to fatigue, rubber dries out faster, and grease can separate. That's not to say an old car will break down in 90-degree weather, But I would pay attention to hoses, plastic fittings under the hood to make sure they're in good condition for the summer.

When I had my old 1999 Deville, I burnt out my alternator with 120K miles on a 95F day. I had the blower motor on high, the coolant fans were running on high and I was in traffic. The high load in addition to the heat caused the voltage regulator to burn out. I've also seen grease seep out from a tensioner pulley and coolant start seeping.

 

[Nick1994]

35C is nothing, and 100C coolant isn't either. I wish my Jeep ran that cool.

@Falcon_LS sees the highest temps of anyone with his cars.

 

[Chris142]

Most cars have a 195 thermostat. It's fully open around 210. The radiator fans usually come on low around 225. High speed fans come on about 235. Generally engines don't like to be over 250.

 

[Chris142]

35C is nothing, and 100C coolant isn't either. I wish my Jeep ran that cool.

Same. 95 is warm but not unbearable.

 

[blufeb95]

35C is nothing, and 100C coolant isn't either. I wish my Jeep ran that cool.

@Falcon_LS sees the highest temps of anyone with his cars.

In this heatwave the Northwest and parts of Pacific Canada is seeing temperatures as high as 45C.

 

[BrianF]

Even us prairie folk will be seeing +36c this week. But never fear!! In 6 months we will be -36c.

 

[Chris142]

In this heatwave the Northwest and parts of Pacific Canada is seeing temperatures as high as 45C.

Hot if you are not used to it.

 

[1uz_4me]

In this heatwave the Northwest and parts of Pacific Canada is seeing temperatures as high as 45C.

While you may think it's 'end of the world' hot, it's really not. I commuted for years from Riverside County to San Diego County in SoCal. Temps are routinely over 110° F for months. Heavy traffic during the week days in 110°+ heat. 348k mi on my GS400. Any mildly maintained car will be just fine.

Friends & I did track days in the same heat with our fox body Mustangs. No one ever blew up, not even 1 friends Kenne Bell supercharged fox. Those aren't intercooled & it only had a home brew water injection kit on it.

 

[Rochev]

Cold startups on the other hand....

 

[Falcon_LS]

35C is nothing, and 100C coolant isn't either. I wish my Jeep ran that cool.

@Falcon_LS sees the highest temps of anyone with his cars.

Ditto.

Right now it's 10:20 and the ambient temperature is 120°F (49°C), my coolant temperatures ranged from 216°F (102°C) - 222°F (106°C) on a 20 minute highway drive.

 

[zzyzzx]

I'm guessing that the OP really doesn't have to worry about this, considering where they live.

 

[zfasts03]

Extreme cold is way harder on the vehicle systems than extreme heat. Check out the cold start videos at -40 and you'll see what I mean!

 

[tyman]

The hottest ambient we saw while we were in Baghdad was 122*. Our up-armored Suburbans with the 8.1l Vortec didn't have any problems with that nor did our Humvees. The only time it came into play was when we idled for hours on end with the hoods shut, the AC system would bog down. As soon as we opened the hood though, they perked right back up.

 

[blupupher]

Hot if you are not used to it.

but your car will not care.

So long as your cooling system is in good shape with a 50/50 mix you will be fine.
Only issue may be how well the A/C works if it is not filled completely.

As others have said, most manufacturers test their vehicles in 110°+ F (43°C) conditions and are designed for higher.
There are times when we have weeks where the highs run 95°F or higher, and there are no issues for most people with vehicles in good condition.

 

[Chris142]

We tend to compare our comfort to an engine. we like about 70f. An engine likes about 200f.

 

[Jimmy_Russells]

In this heatwave the Northwest and parts of Pacific Canada is seeing temperatures as high as 45C.

Ditto.

Right now it's 10:20 and the ambient temperature is 120°F (49°C), my coolant temperatures ranged from 216°F (102°C) - 222°F (106°C) on a 20 minute highway drive.

The highest temperature ever recorded in Canada yesterday, 47.9°C in Lytton, BC.

It is hot as balls here guys, not many people have A/C and it isn't like 0% humidity. The main floor of my house was 36°C yesterday and 32.5° at 7:30 AM this morning.

 

[2strokeNorthstar]

Driving my 98 BMW through the desert last weekend it hit 114 degrees outside. A/C had a hard time keeping us cool with the dark colored paint and blazing sun through the windows but engine seemed fine. Cooling system had been overhauled more than once of course.

 

[eljefino]

We tend to compare our comfort to an engine. we like about 70f. An engine likes about 200f.

Yup and the cooling system just has to work 30% harder which is designed in overhead.

Many of us are spoiled and just have the thermostat half-cracked with the rad fans never coming on unless there's a traffic jam.

That all said if I've been in a jam for a while and the gauge needle's getting up there I gently nurse the car back up to speed when things clear out.

I lost a rear tire on my saturn in a heat wave once... chinese... properly inflated, rear axle, probably 400 lbs on it, tire just hated life that day.

 

[40w8]

MY Mazda RX8 went right up to 213deg f idling with AC on any hot day. You better keep moving or under hood could get 190deg f. I put a Auto trans cooler on it and both engine water temp and ATF can get down to 193 deg f while driving 100 mph @ 100 deg f.

Almost no other car is fussy about high ambient heat. It's the tires and batteries that over 100 deg f will eat though. What's really damaging is the UV radiation from sun burning the paint and interior.