When bleeding brakes, it is generally recommended to keep the cap on the brake fluid reservoir. However, there are a few important considerations to keep in mind:
Safety: The brake fluid reservoir cap is designed to contain the brake fluid and prevent it from splashing or spilling. Keeping the cap on during the bleeding process helps maintain a clean and safe working environment, minimizing the risk of brake fluid coming into contact with your skin or damaging other components of the vehicle.
Air introduction: Removing the cap while bleeding brakes can potentially introduce air into the brake system. Air bubbles in the brake lines can compromise braking performance and require additional bleeding to remove. To ensure a proper brake bleeding process, it is generally recommended to leave the cap on to maintain a closed system and minimize the risk of air entering the brake lines.
Different vehicles and brake systems may have variations in the bleeding process, so it's important to follow the specific instructions provided for your vehicle model to ensure proper brake maintenance and safety.