Cooling system: Difference between revisions

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As you tootle along at a sedate pace on a residential street, your engine is generating a small amount of heat -- pouring water into the tank. The drain pump is more than large enough to get rid of any excess water. As you go faster, the engine generates more heat, filling the tank faster. The drain pump is still up to it, including absolute top-speed on a hot day. However, the tank gets fuller the faster you go, storing more heat energy in the engine. The cooling system can still get rid of enough heat to keep the engine in the right range, but that's about it. The tank fills to a good level, but doesn't overflow.

Now, imagine you get off the freeway and pull up to a stoplight. Your heat/water tank is full, because you've been generating a lot of heat driving fast. The cooling system was able to drain off enough heat to keep things under control, but the tank filled up in the mean time. Now that you're stopped, the air flowing over the radiator is reduced to zero (which means your drain pump is down to zero pumping power). Suddenly, any excess heat at all (such as running the engine at idle) is enough to overflow the tank, because it's so full. The temperature gauge shoots up until the fan kicks in -- there's the drain pump stepping in at the last minute before the tank overflows.

[[Image:Lowspeed.png|180px]] [[Image: Highspeed.png|180px]] [[Image:Highheat.png|180px]]

(Please excuse the crudity of the diagrams.)

Now, imagine you get off the freeway and pull up to a stoplight. Your heat/water tank is full, because you've been generating a lot of heat driving fast. The cooling system was able to drain off enough heat to keep things under control, but the tank filled up in the mean time. Now that you're stopped, the air flowing over the radiator is reduced to zero (which means your drain pump is down to zero pumping power). Suddenly, any excess heat at all (such as running the engine at idle) is enough to overflow the tank, because it's so full. The temperature gauge shoots up until the fan kicks in -- there's the drain pump stepping in at the last minute before the tank overflows. This situation (before the fan kicks in) is shown in the third diagram.

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 As you tootle along at a sedate pace on a residential street, your engine is generating a small amount of heat -- pouring water into the tank.  The drain pump is more than large enough to get rid of any excess water.  As you go faster, the engine generates more heat, filling the tank faster.  The drain pump is still up to it, including absolute top-speed on a hot day.  However, the tank gets fuller the faster you go, storing more heat energy in the engine.  The cooling system can still get rid of enough heat to keep the engine in the right range, but that's about it.  The tank fills to a good level, but doesn't overflow.
-Now, imagine you get off the freeway and pull up to a stoplight.  Your heat/water tank is full, because you've been generating a lot of heat driving fast.  The cooling system was able to drain off enough heat to keep things under control, but the tank filled up in the mean time.  Now that you're stopped, the air flowing over the radiator is reduced to zero (which means your drain pump is down to zero pumping power).  Suddenly, any excess heat at all (such as running the engine at idle) is enough to overflow the tank, because it's so full.  The temperature gauge shoots up until the fan kicks in -- there's the drain pump stepping in at the last minute before the tank overflows.
+[[Image:Lowspeed.png|180px]] [[Image: Highspeed.png|180px]] [[Image:Highheat.png|180px]]
+(Please excuse the crudity of the diagrams.)
+Now, imagine you get off the freeway and pull up to a stoplight.  Your heat/water tank is full, because you've been generating a lot of heat driving fast.  The cooling system was able to drain off enough heat to keep things under control, but the tank filled up in the mean time.  Now that you're stopped, the air flowing over the radiator is reduced to zero (which means your drain pump is down to zero pumping power).  Suddenly, any excess heat at all (such as running the engine at idle) is enough to overflow the tank, because it's so full.  The temperature gauge shoots up until the fan kicks in -- there's the drain pump stepping in at the last minute before the tank overflows.  This situation (before the fan kicks in) is shown in the third diagram.