Quite often, working on a vintage or late-model Mustang is fun. A large part of that is due to an intriguing upgrade, such as installing a four-barrel carburetor and intake in place of a two-barrel.

Anyone who has tackled heater core replacement will tell you they’d rather have an all-night root canal than have to perform this dreaded task. Heater core leakage begins with the subtle aroma of ...