Cooling system: Difference between revisions
| (10 intermediate revisions by the same user not shown) | |||
| Line 6: | Line 6: | ||
In normal operation, assuming a system in correct working order and filled with coolant, the engine will remain at the correct operating temperature almost entirely through natural convection, as air moves past the radiator. The air moving past the radiator carries away heat, removing it from the engine. In some circumstances, the cooling system either doesn't receive enough air, or doesn't receive cool enough air, and it will engage the electric fan. This typically happens when the air temperature is over about 80° F (27° C), or when the bike is stopped or moving very slowly. | In normal operation, assuming a system in correct working order and filled with coolant, the engine will remain at the correct operating temperature almost entirely through natural convection, as air moves past the radiator. The air moving past the radiator carries away heat, removing it from the engine. In some circumstances, the cooling system either doesn't receive enough air, or doesn't receive cool enough air, and it will engage the electric fan. This typically happens when the air temperature is over about 80° F (27° C), or when the bike is stopped or moving very slowly. | ||
Another important part of the cooling system is the thermostat, #49054 in the diagram: | |||
[[image:RADIATOR.png|100px]] | |||
The thermostat feels the temperature of the engine and decides how much cool water it should be fed with, in order to keep the engine temp stable. The thermostat keeps a minimum flow of water into the radiator while the engine warms up. This helps bring the engine up to proper operating temperature more quickly. (That's a good thing.) | |||
After the engine reaches the proper temperature of operation, the thermostat opens gradually, but only enough to keep that temperature in the engine constant, avoiding over-cooling. | |||
If the cooling of the water in the radiator is not enough, even when the thermostat is fully open, then the electric fan starts. | |||
This schematic shows the components of the Ninja 250 cooling system and how they relate to each other. | This schematic shows the components of the Ninja 250 cooling system and how they relate to each other. | ||
| Line 19: | Line 28: | ||
3. The fan comes on when the coolant gets above about 225F. It stays running until the coolant temperature falls back below 205F. | 3. The fan comes on when the coolant gets above about 225F. It stays running until the coolant temperature falls back below 205F. | ||
4. At 10,000 rpm, the water pump pushes the coolant through at eleven gallons per minute, which means that the single quart of liquid in the system is doing a circuit 40 times a minute. Be kind to your hard-working coolant and change it regularly. | 4. At 10,000 rpm, the water pump pushes the coolant through at eleven gallons per minute, which means that the single quart of liquid in the system is (theoretically) doing a circuit 40 times a minute. Be kind to your hard-working coolant and [[How do I service the cooling system?|change it]] regularly. | ||
==Reading the temp gauge== | ==Reading the temp gauge== | ||
| Line 40: | Line 49: | ||
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 as long as you were moving, 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. | 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 as long as you were moving, 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. | ||
==More info== | |||
For a little extra reading on the cooling system, we suggest the following: | |||
http://www.stewartcomponents.com/tech_tips/Tech_Tips_6.htm | |||
http://www.arrowheadradiator.com/14_rules_for_improving_engine_cooling_system_capability_in_high-performance_automobiles.htm | |||
http://www.engineeringtoolbox.com/pumps-discharge-regulation-d_310.html | |||
http://www.arrowheadradiator.com/Radiator_Diagnosis,_%20Repair,_%20&_%20Replacement_%20Tips.htm | |||
http://www.arrowheadradiator.com/overheating_causes_and_cures.htm | |||
http://www.familycar.com/Classroom/CoolingSystem.htm | |||