17

Generally, the outside temperature sensor is located under the front of the hood near the bottom of the car. Although the sensor itself is accurate, the location causes the sensor to pick up heat from the road surface. Thus, it will usually read several degrees higher than the air temperature. This is especially noticeable when driving on high speed ...


11

The exact time taken depends upon various factors: The ambient temperature The amount of heat insulation in the engine bay Volume of coolant in the engine How hot the engine got while driving material used in construction of the engine block/head (aluminium blocks cool quicker than steel for example) and many more besides. Typically though it should be ...


10

You won't damage a vehicle by shutting it off before it gets to full operating temperature. This, in some places, could be considered a waste of gas. There are two things you need to be aware of though. If you are continually doing this on a regular basis, you will cause condensation in the crank case. This excess moisture can contaminate the oil and ...


10

I can see a few reasons to do this: The weather in some places will be so cold that even with the thermostat fully closed the cooling system isn't able to warm the engine up to operating temperatures. Inhibiting air flow through the radiator will reduce the amount of heat rejected to the surroundings, allowing the engine to get up to temperature. The cold ...


10

You have a qualitative description of what happens, but let's break it down to a smaller scale. When we talk about "temperature" of something, we are really talking about how fast the molecules are moving around and bouncing off each other. "Temperature" is really "kinetic energy". And it turns out that there are other types of energy besides moving around ...


9

The short answer: Yes, you can rev your engine to make it warm up faster. One big caveat to that answer is that it is highly recommended you don't do that. With modern gasoline vehicles, most manufacturers recommend you start the car and immediately start driving. The reasons for this are many, but a couple of the major points: The car will warm up faster ...


9

It varies a lot, but in general it is placed somewhere where it will get as accurate a reading as possible - avoiding engine heat etc. In most of mine it has been low down behind the front bumper, but I did have one car that had the sensor below the driver's door. Misplacement may lead to the effect @Barry pointed out, but in any case, many are ...


8

Definitely air conditioning requires more energy, since heat is, as correctly stated in the other answer "basically free" because it's the waste heat from your engine. According to this study by R. Farrington and J. Rugh of the National Renewable Energy Laboratory (NREL), Current air-conditioning systems can reduce the fuel economy of high fuel-economy ...


7

Heat is basically free: your car's heating system works by diverting some of the engine coolant through the heater block rather than the radiator, with the result that waste heat gets dumped into the cabin rather than the outside world. In contrast, air-conditioning works by connecting the AC's compressor to the engine output, drawing off energy that would ...


7

This is old, but some of these comments annoy me. I live in Fairbanks AK and drive a 90's diesel Chevy. It takes a 15 minute idle period (in addition to at least an hour with the block heater plugged in) and 3-5 miles of highway driving for the coolant temp to get over 120 degrees when it's 10 degrees or colder. When the temp is below -20f or so, the ...


7

Funny you should ask this Max :) First lets make sure of our definition. Running an engine lean means changing the air / fuel ratio to have more air than is ideal (14.7:1 air to fuel). In my reading there are two effects. First, the fuel is an atomized liquid which has a cooling effect on the combustion chamber. So less fuel, less cooling effect. Second, ...


7

From what I remember from my Civic driving days, the radiator in that car only extends half way across the grill of the car, and the other half is blocked off by a plastic cover as you mentioned. You also mentioned that you removed this cover in the summer to increase airflow to the engine. This is actually the opposite of what you should have done, ...


6

When the temperature is 0 Celsius (32°F), ice is likely to be visible and drivers will be aware. Typically they will be driving carefully, and may even be on winter tyres. Where the temperature is falling through 4 degrees (40°F), most road conditions will be fine, but there may be parts of roads (eg in the shade) that are at 0 or below and could be icy. ...


6

Oil leak is unrelated. You should fix that. (: There are various possibilities: The temperature gauge is faulty or the sender that sends the gauge the temperature reading is. Test: Block part of the front of the radiator with a piece of cardboard. This will force the system temperature to raise. Drive around for a little. Watch the gauge. Does it go to ...


6

According to this paper: Normal operating temperature for an automatic transmission is about the same as the engine temperature, i.e., about 195°F. The temperature inside the torque converter, while pulling a big load from a standing start, could easily rise above 350°F. EDITORY NOTE: I'm seeing this same basic range at many different sites.


6

An anectodal answer to this... Back in the '70s I owned a Moskvich 412, a Russian car built to survive in Siberia. This had a brass venetian blind arrangement in front of the radiator that could be opened and closed from a lever beside the steering wheel. The handbook stated that this blind should be closed when starting the vehicle at temperatures below -...


6

I would seriously look at improving your oil cooler. I doubt going "larger" is the immediate solution, I'm betting it's the airflow across the heat exchanger. Relocate the cooler, modify/improve the ducting, find cooler air to flow across it, etc. On my FPROD '72 BMW 2002tii, I was able to drop oil temperatures from a frightening 280 F peak, to a more ...


6

Let's see. 80 km/h is 22.22 m/s, and the kinetic energy is 0.5*1200 kg*(22.22 m/s)^2 = about 300 kJ. Brake rotor is initially at 20 degrees Celsius and now rose to 100 degrees Celsius. That's a 80 degree rise. Brake rotor weighs about 10 kg (source). There are 4 rotors, or 40 kg total in the car. Grey cast iron has 490 J/(kg*K) heat capacity. This means 40 ...


5

If you have ever seen an oxy-acetylene torch being used, you will have noticed that before the oxygen is turned on, the torch has a bright yellow flame. This is the fuel burning in a less than ideal amount of oxygen. The flame is relatively cool and it produces a lot of soot. When the oxygen is turned on, tthe flame turns blue and becomes hot enough to ...


5

Sounds like the temperature sensor is broken. A new one is $40-$55, and it's a 30 minute job to replace if you've never done it before (it lives behind the grill in front of the radiator). Not uncommon for these to fail on Subarus and give weird readings. Following Paulster2's comment, here's an image of what the sensor looks like; In this image (of a 2007 ...


5

The coolant ratio does affect how the system cools the engine, but probably not as you'd think. Water is a better thermal conductor than is the antifreeze, so it will do a great job of shedding the heat of the engine. Water by itself does boil sooner than an antifreeze/coolant mix, though, so you could expect it to boil over sooner than without the ...


5

I live in a very hot climate. There is no issue in turning on a properly-functioning A/C to its maximum setting at startup. Turning the A/C on activates the refrigeration cycle, which at startup will have the same load on the compressor regardless of the temperature setting selected. This is part of the reason why the cooling effect isn't instantaneous, ...


5

The hottest part of the wheels after driving will be the brake discs which can easily exceed 100 °C. In this video, Jason puts a thermal imaging camera to good use. Temperatures exceed 140 °C:


5

If you have any doubts, don't do any of this, just wait til the system is cool to the touch. Steam is extremely dangerous! With that said, you can open the system a lot sooner than a matter of hours, and possibly much sooner than 30 minutes, if you need to. The easiest way to gauge if it's under sufficient pressure that you shouldn't open it is trying to ...


4

It depends on the vehicle, why it is being left, and how it is prepared before being left. If it's a vehicle that's in reasonably regular use, then I'd recommend making sure it's used at least once every week or so, and is driven far enough for the engine to get up to full operating temperature. Just starting it and letting it run is better than nothing (e....


4

To expand on Poisson's answer given your edit - Yes, you can, but still shouldn't ;) . By the time you've scraped the ice off the side windows the demisters should have done the job with the front and rear screens (or at least loosened the ice enough to make it easy to wipe off), at which point you're good to go...


4

The thermostat would have been my first guess too. It doesn't need a sealing ring, the housing will slightly clamp it when you put it back together. It is entirely possible that the temperature sensor has 'drifted' and is reading lower than the genuine temperature. I have experienced this more than once in my own cars. It's worth as try as they're usually ...


4

Orthodox antifreeze is based on ethelyne Glycol. It does depress the freezing point and raise the boiling point of the cooling system. This is desirable and the suggested concentration is roughly proportional to how cold you think it's going to get. As a coolant, water just can't be beaten so that's why it's still used on the internal combustion engine over ...


4

I'm guessing you've got a 13 psi radiator / cooling system cap. The 13 PSI number is pretty standard for GM cars. At that pressure, water doesn't boil (from liquid to vapor) until 245 deg F or so. What you are seeing is totally normal. The manufacturer uses those pressures to improve radiator vehicle cooling performance. If while driving on a hot day ...


4

A thermocouple merely generates voltage according to the temperature, while an automotive thermostat is basically an autonomous temperature sensitive coolant valve. You can't replace a thermostat with a thermocouple because their functions are completely different. You could replace a coolant sensor with a thermocouple, but resistive sensors are more ...


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