Is it bad to engine brake with a manual transmission? The short answer is no. As long as you are doing it right and not slipping the clutch or kicking down a gear and subjecting the drive line to unnecessary shock, engine braking is completely harmless. In fact, it’s one of the most efficient things you could be doing.
When you get off the gas to slow down, the engine slows due to the vacuum produced behind the closed butterfly valve of the throttle. This slows the car without even using the brakes, ensuring less heat, and therefore wear, goes into the brake components.
But that energy has to go somewhere, so is pouring extra energy into the engine bad? Again, no. The engine is designed to handle so much more heat than engine braking introduces, it will never approach stressing the cooling system compared to what it usually handles.
Now if your cooling system can’t help coasting to a stop, you have bigger problems on your hands. But at least you know you can engine brake without worry.
Related: Just What Is Engine Braking?