Heat Wave: Maximum Ambient Operating Temperature for a Vehicle?

yet every year there's some, even with brand new cars that have brake failure coming down the Alps... I'm sure the Rockies won't be much different
Oh yeah. Actually here at Pikes Peak we have a brake checkpoint. When people are coming down they check the temperature of rotors. I have seen people having brakes heated to the same level as I do on the track.
 
Oh yeah. Actually here at Pikes Peak we have a brake checkpoint. When people are coming down they check the temperature of rotors. I have seen people having brakes heated to the same level as I do on the track.
We also have runaway lane on the Grapevine at I5 going downhill from South to North direction, mainly for runaway semi.

 
The media says it is historic and cataclysmic and a bunch of other scary adjectives but no need to worry. It’s a lot hotter inside the engine. Your vehicle will be fine as a long as you kept up with maintenance, especially the cooling system.
 
They need to learn how to shift the car down to a lower gear in manual or L / D2 / D3 etc in automatic, engine braking is not just for racing.
Yep… my parents experienced some pretty heavy brake fade in Georgia coming down the side of a mountain in their rental Grand Caravan, while asking me why I’m “driving like a fool” in front of them, my Durango had aftermarket mufflers that truly did sound wonderful, if a bit loud, coasting at 3,000rpm lol. I had to explain that I was in 2nd gear with my rpms hovering around 3000-4000 coasting and showed them how to select a gear in their van.
 
It's been hot around here. I've never heard by electric fan so much before, especially since I'm always in slow traffic and taking calls in the car so it just sits with the ac blasting. The fan feels like the weak link. Given the variable coolant temp, I assume all is well. Oil temp is the usual summer 240F.
 
On my own vehicle, I would worry more about TX temperature, than motor oil or coolant temp in extreme ambient temps.

I have an additional cooler, plumbed inline after the radiator exchanger and a derale external mount filter mounted after both.

I attached K type thermocouples then insulated them, to the TCX cooler line at radiator inlet, and at the output of the additional filter, an Farm Ultra XG16

When climbing the mountains east of San Diego on I-8, which are pretty steep if only getting to ~4100 feet, the TX fluid leaving the filter, was often hotter than the TX fluid entering the radiator. It was entering the radiator at 150f or so and coming out the filter at 168f at the highest I noticed.

If I did not have the additional cooler, after the radiator heat exchanger, the fluid going back to the TX would be way hotter than that which entered the radiator's heat exchanger instead of just 18 f hotter.

I never saw more than 168f with newly refreshed ATF+4, so I did not worry about it, but the Data surprised me, as it often does, when one bothers to actually collect it.

If I did not have the additional TX cooler, not only would the fluid returning to the Tx be significantly hotter, but would also be imparting more heat to the circulating coolant.

But the data was also accrued in December with mild ambient temps after dark.

I did not expect the radiator to warm the TX fluid as much as it did, but when climbing grades and watching the temp displays, seeing the post filter TX fluid temp higher than the temp entering the radiator from TX, made me think something was wrong with teh thermocouples, or my insultion covering them so they would more accurately reflect the temp of the fluid in the lines.

I doubled the insulation and double checked with my IR temp gun at idle , and while it was not dead nuts accurate, they were not more than 10% out of line with each other.

My additional cheap fin and tube TX cooler is obviously just big enough, but does not have much overhead for extreme ambient temps, as the radiator dumps so much heat to the TX fluid.
 
I am in Terrace BC right now. Right in the middle of that heat wave. it hit 38c outside here. My car interior hit 60c.

Car ran fine. I think the bigger risk is stuff melting in the cabin. Aftermarket electronics maybe seeing a short life and trim adhesive coming loose.
 
Too hot is when your coolant overflow bottle overflows because the radiator pressure cap can not maintain coolant in the system because the coolant is not being cooled enough and the engine is still running and the fan(s) is / are on. This assumes that the radiator pressure cap is releasing at the original manufacturers designed pressure, which is chosen by designed to correspond with the pressure the antifreeze with proper water percent mix, will produce when it is too hot.

Usually when this happens the cause is a clogged radiator that is not allowing the coolant to come into enough contact of surface area inside the radiator to cool enough, or something in the fan system not allowing enough air to flow, a bad fan, or a bad temperature sensor that should be providing a signal used to determine when a fan should come on, or some of the newer trucks with a bad radiator shutter system, come to mind, or the water-pump is not pumping fluid flow fast enough ( worn out or corroded impeller inside the pump can be one of the causes ).

A little expansion overflow into the overflow bottle after shutdown from the cooling system getting too hot for a short time when the water-pump and maybe the fans are not running is normal. And as soon as the engine cools off enough the coolant still in the engine and radiator actually reduces in volume and that little bit that went into the overflow is sucked back into the coolant system.

If you want an idiot light that goes on to tell you the system is really running too hot, besides the coolant temperature gauge, one way would be to install a very high level detection switch ( such as a float switch or some of the electronic fluid level detection switches ) to sense the level inside the top section of the overflow bottle, connected to a very noticeable bright red light on the dash. It the overflow bottle is being filled to an unusual high level, you have some kind of an over heating or blown head gasket problem going on.
 
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The cooling fan in my truck doesn’t come on until the coolant hits >217F. Manufacturers test vehicles in conditions worse than what you’re seeing. The vehicle will be fine. You on the other hand try to stay cool. Hopefully this passes soon for you!

just my $0.02
 
For the most part, ditching the stupid plastic engine cover will allow the electrical connectors and vacuum hoses a longer lifespan. Save it and put it back on if you sell the car.
Any idea how much cooler an engine might be without the cover ... I know that "it depends" but would you think maybe 5 or 10 degrees, or maybe 20 or 30 degrees? Anyone done any tests on their own cars?
 
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.

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.
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.
195 seems a little high at least for my application. Mine's a 180 thermostat and always runs at 181.4 exactly at full operating temperature. The fans kick in at 203. Also if yours is designed for 195, wouldn't it BE fully opened at 195. Don't thermostats start to open just before their designed temp and are then fully opened at that temp. So correct me if I'm wrong but you're saying in your case it only fully opens 15 degrees hotter than it's spec'd temperature? Not sure about that one.
 
Any idea how much cooler an engine might be without the cover ... I know that "it depends" but would you think maybe 5 or 10 degrees, or maybe 20 or 30 degrees? Anyone done any tests on their own cars?
It really depends on the vehicle. Some have covers that are purely aesthetic, some are used as sound deadening, and some are actually useful for under hood airflow, and some are a combination of 2 or more of these.

I would say the for the majority of vehicles and conditions used in, it really will not make a difference in a well maintained modern vehicle.
 
195 seems a little high at least for my application. Mine's a 180 thermostat and always runs at 181.4 exactly at full operating temperature. The fans kick in at 203. Also if yours is designed for 195, wouldn't it BE fully opened at 195. Don't thermostats start to open just before their designed temp and are then fully opened at that temp. So correct me if I'm wrong but you're saying in your case it only fully opens 15 degrees hotter than it's spec'd temperature? Not sure about that one.
Thermostats BEGIN to open at the rated temp.fully open about 10-15 degrees higher.
 
I have seen references to using only a 30/70 concentration of coolant to water when you live in the south. That would result in a boiling temperature of 220 F at sea level, un-pressurized. Using a 60/40 concentration of coolant to water would result in a boiling temperature of 232 F. This is for ethylene glycol coolant which by the way is the basis of most coolants regardless of colour. Of course, pressurization increases the boiling temperature. Here is a chart of boiling temperatures of different ethylene glycol mixtures at different pressures.

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100 C coolant is nothing. For any modern vehicle, I would not begin to worry until the coolant shows 110 C (230 F), at which point the radiator fans should be running and the coolant temp dropping fast. Engines are now designed to run hotter than in the past, this is to increase fuel efficiency.
That is interesting you can see all the little details on the OBD monitor. Most engine temp dash gauges are designed to show "normal" until the temp gets significantly outside of a set range, which means the gauge is slightly better than a dummy light. This is to keep new owners from crapping their pants because their brand new car *appears* to be overheating. I am in the habit of shutting off the engine when stopped longer than a minute or so -- this scenario is easy to anticipate when driving the same route to/from work day after day. I shut off to keep engine temps normal and to save a little fuel. I am very mindful about excess heat in the tires and brakes as that could lead to a dangerous situation.
The great thing about high ambient temps is that my engine reaches full temp in just a couple minutes, and the amazing fuel economy :D
 
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