Traffic accidents in Indonesia often occur due to failure on the braking system. The results of the KNKT investigation show that there are three phenomena that most often cause brake system failure, namely brake fading, a decrease in the volume of compressed air and vapor lock. The aim of this research is to conduct experimental studies and develop designs for vapor lock detection devices to prevent failure in the braking system. Experimental studies on vapor lock characteristics were carried out through observations and measurements of boiling points and bubbles (the beginning of vapor lock) in the brake fluid heating process with various variations in water content. Experiments on vapor lock characteristics show that increasing the percentage of water content in the brake fluid has an effect on reducing the boiling point of the brake fluid and an empirical equation is produced to predict the boiling point of the brake fluid based on the percentage of water content in it. Apart from that, we have successfully developed a design for a vapor lock detection device to prevent failure in the braking system which is equipped with a water cooler brake system to prevent the temperature from reaching the boiling point of the brake fluid.