The cooling system of the FC3S becomes overtaxed when extracting more power.  Due to the age and mileage of the FC3S's still around, the radiator is prone to failure due to it's composite construction:  the core is aluminum, crimped to plastic end-tanks.  Upgrade/larger radiators are recommended for ALL FC's.

Those that race their FC3S's create additional problems by constantly revving the motors at high RPM's; the stock water pump was not designed to work efficiently under constant, high RPM duty.  Underdrive pulleys can solve this problem by slowing down the water pump.

Tearing down high mileage motors, we have found large accumulations of "sand" or gritty deposits that settle into the coolant passages of the engine housings.  We recommend the cooling system flushed thoroughly at least once a year.

Normally flushing procedures call for running the motors at normal, operating temperatures for approximately 10 minutes; read the container for detailed instructions.  We've found that this does not sufficiently flush the motor of contaminents.  This is a modified flush procedure:

Due to the controversial nature of this modified flushing procedure, we must include the follow disclaimer - proceed at your own risk; FC3S Pro is not responsible for any damages.

  1. Drain entire cooling system (of coolant) - on the 13B, use the radiator drain (plastic plug) on the bottom of the radiator and the engine block drain (14mm hex plug) located in the driver's side engine mount bracket.
  2. Close drains and fill with your favorite flushing additive.  We recommend using Prestone Superflush™.
  3. After pouring in bottle of Prestone Superflush, top off with water as per instructions on the Prestone Superfluch bottle.  The cooling system should now be filled with the Prestone Superflush and water mix.
  4. Start the car and run till the cooling system boils over.  Yes, you heard that right - till you see steam coming out of the overflow bottle.  You might need to drive the car around the block a few times to get it to steam; it might not steam just idling in your driveway.  Try not to drive very far away from home when doing this.  Stay calm and do not get alarmed when the temperature gauge hits "H" and the low coolant light/buzzer goes off.  As soon as you gauge hits "H", calmly drive back home and kill the engine.
  5. Shut the engine down and let it cool down.
  6. Drain everything out of the cooling system - it should look milky white!
  7. Flush the cooling system with as much running water until everything comes out clear.  Don't forget to flush and clean out your overflow bottle also!
  8. Drain and fill with your favorite coolant and (distilled) water to the appropriate ratio depending on your climate.  Again, don't forget to fill the overflow bottle also.

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