A coolant leak is a progenitor to a deadly engine problem. Thus, fixing coolant leak timely should have to be given top preference. Coolant leak causes car engine to overheat. It reduces the overall engine performance. Sometimes, it can lead to engine misfiring as well. Remember- the optimum level of antifreeze needs to be maintained as it keeps the car engine cool in summer and prevents the engine from freezing in winter. If you find your car is leaking coolant, then consult a car serviceman and fix the leak as soon as possible.