Heatsoak

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Hello all,

I would like to start by saying that, being the car enthusiast I am, really enjoying reading about the various topics posted in the forum along with the very informative content of the site. I have finally registered and am posting a topic of discussion of my own, or as I would like to facetiously refer to as my "Hello World" post as this is my first topic. Please forgive me if this has been addressed in the past, I did a quick search and may have overlooked it. But getting on with the discussion at hand, I live in Florida, and have a relatively small one car garage (with no windows) and am a little concerned as in the summer months it, gets quite warm. After driving with the AC cranked, I pull my car in this quaint garage of mine with barely enough clearance for my side rear view mirrors, shut the engine off and then dread the heating of the engine and the engine compartment of my fairly new 2013 Ford Taurus SEL. My research on the topic could be summarized by the events that take place below in order when the engine is shut off.

1. The heat contained in the cylinder walls is obsorbed by the coolant, excessively heating it.
2. The coolant pressure possibly rises, depending upon what the pressure initially was at shut down, which fortunately increases the boiling point.
3. Provided the coolant does not come to a boil in the engine; less so if it does, the heat excess heat will be expelled by mainly one of two ways, through engine surface radiation or through the heat transfer to the radiator through the hoses (through a method I believe to be called conduction).

I am concerned, as the cooling process takes quite a while longer than when the car is parked outside. As part of my research I have also read that in some vehicles the CCRM is programed to monitor the temperatures even after the engine is shut down and will activate the fans if the temperature exceeds some threshold, though I am not sure if this is applicable to my particular car. Additionally, there is a sticker that indicates the cooling fans may start at any time, but I wonder if placing this sticker under the hood is something that's perfunctory for car manufactures to do regardless of whether or not it pertains to that particular vehicle (engine size, accessories, etc.). Lastly, I have checked the temperature gauge after shutting it down and fortunately its always stationary in the middle until the engine starts to cool, then of course I goes down. To cool it off, I have opened the hood before but that's kind of inconvenient, also due to the low ground clearance and the active radiator shutters (though open still restrict some air) a fan doesn't really help much. Ultimately, I am concerned as to whether or not this extended cool down time is detrimental to the engine in the long run, and what fail safes are in place to prevent it from causing damage it in extreme circumstances like on really hot days.

Any ideas?

Thank you for reading
 
I do not think most of us worry about it. I had a 2000 VW Passat that would circulate water through the engine after turning the key off. I always thought it was over engineered.

Once the engine shuts down and the coolant is no longer pumping, it probably will get hotter around the cylinders, but with no more heat being produced the coolant can handle it.

The temp gauge only pulls info from one location, and when the water pump is no longer moving the water, the temp gauge will not be too accurate.

My Dad had an old Farmall tractor (crank start) and I do not believe it had a water pump. The water moved by convection.

Some coolant gauges are fed data from the ECM (my Cummins diesel) and they show what the ECM says to show.

At the end of the day (assuming decent maint), it will not be the engine that causes the car to go to the boneyard.
 
The last time I worried about such a thing was in the days of vapor lock. And Donald, my Audi was the same way - it would run coolant backwards through the system and blow a special fan on the injectors if they were hot.
 
My BMW will show an increase of the coolant temp after shut down of about 7-10 degrees F using my AutoEnginuity ODBII software. (this was measured while I was in Houston, TX.) The coolant sensor is located in the rear of the cylinder head.

The temp gauge on my BMW is "buffered" and will read in the middle from about 180 to 220 F. BMW also includes a "post heating filter" to keep the gauge from showing the higher temp when you restart the engine-

Since, after shut-down, the engine still heats the coolant for a certain period of time, an increase in the gauge temperature when the engine is stationary is prevented by a "post-heating filter" in the software of the instrument cluster. When the engine is restarted, this function detects a higher temperature than at "engine off" and indicates this "engine off" value. The current temperature is then indicated after 20 seconds with the engine running.


Keeping the engine warm should actually HELP the engine, when cool (even 100F) your oil is much thicker than the engine actually needs
smile.gif
 
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Shanneba,

What happens to the oil temp? That is the interesting one to me, as I only have the dash oil temp to go by. Seems like a good number of members from Houston on here.

Originally Posted By: shanneba
My BMW will show an increase of the coolant temp after shut down of about 7-10 degrees F using my AutoEnginuity ODBII software. (this was measured while I was in Houston, TX.) The coolant sensor is located in the rear of the cylinder head.

The temp gauge on my BMW is "buffered" and will read in the middle from about 180 to 220 F. BMW also includes a "post heating filter" to keep the gauge from showing the higher temp when you restart the engine-

Since, after shut-down, the engine still heats the coolant for a certain period of time, an increase in the gauge temperature when the engine is stationary is prevented by a "post-heating filter" in the software of the instrument cluster. When the engine is restarted, this function detects a higher temperature than at "engine off" and indicates this "engine off" value. The current temperature is then indicated after 20 seconds with the engine running.


Keeping the engine warm should actually HELP the engine, when cool (even 100F) your oil is much thicker than the engine actually needs
smile.gif
 
That's a good point, starting a warm engine is better for oil flow. I can imagine there would have to be a buffer of some sort on my temp gauge as we'll. Also, I can imagine the reaction of 7-10 degrees would be about the same reaction for my car too as they have many comparable characteristics; tight engine compartment, roughly same sized engine, variable valve timing ( though I doubt that would make a difference) is your block aluminum as well?
 
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You really don't need to worry about it - any responsible car manufacturer tests pre-production models all over the world, from the Arctic to the Sahara and everywhere inbetween..the thermal capacity of your cooling system is more than sufficient to cool the motor.

If you want to feel like you're doing something to help, run the heaters and blowers on full power with the AC off for the last 10 mintes of your drive, easy way to let heat escape before you switch off.

HTH
 
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