After having seen what to do when it’s cold and how those who don’t race in the winter put the radiator away, we now take a look at the work that needs to be performed on the radiator before taking the kart back out on the track and the mistakes to avoid so as not to jeopardise the proper functioning of the vehicle.

• Precautions to get going again
The best time to work on a radiator is immediately after removing the kart from its winter “hibernation”. Firstly, you need to check the fins on the griller: if most of them are closed, you have to change the radiator.

However, if the fins are ok, you can fill the radiator with water. The task, in itself, is easy. The problem you need to take care over is the formation of any air bubbles. In fact, were they to remain in the radiator, they wouldn’t represent a problem, but if they were to reach the water pump, they might halt the circulation of the water itself (which would be dangerous for the engine). In fact, the pump would turn pointlessly inside the air bubble and there wouldn’t be enough pressure to make the water circulate inside the circuit.

• How to deal with air bubbles

There is a procedure you can follow to prevent all this from happening. Start by putting water in the radiator right up to the brim, so that it fills the entire circuit. Lift the kart from the radiator side in order to eliminate the air bubbles, which gradually rise to the top, far away from the pump. Then place the kart on the stand, turn it on and let it idle for a while: this is the best way to clean a radiator (and warm up a kart after a long winter). If the water level remains the same after the test, this means that the work was performed properly. Otherwise, you need to repeat the same procedure until the water remains full to the brim even after idling.
Remember, you cannot put liquid other than water in the radiator, because if there were a leak it would make the track slippery and, therefore, very dangerous for both you and others kart drivers.

• Does the radiator work?

When the kart is on the trolley you should also check whether the radiator actually works. The simplest and most effective test is to touch the upper and lower bowls to verify the difference in temperature. In fact, with the kart only just having been turned on, the upper bowl will be hotter than the lower one. However, after a short while the lower one should also heat up, meaning that the circulation of water is working and waiting for the effect of the air (which, of course, cannot enter the radiator with the kart stationary on the stand) to cool the water.
It is also important to check for leaks, which would mean having to replace the radiator.
Finally, you should also check the rubber grommets on the sides of the radiator brackets. Winter may have caused the rubber to harden and crack.