What should be limited to avoid damage to an engine when going downhill?

To prevent damage to an engine when going downhill, it is essential to manage downhill speed effectively. High downhill speeds can lead to increased strain on the engine and its components due to the excessive momentum and pressure generated from gravity. This can result in overheating, mechanical wear, and potentially catastrophic failure if the engine is not able to handle the pressures involved.

Controlling the speed allows for more effective engine braking, which can help maintain a safe pace while also reducing the likelihood of overheating the engine. Proper speed management ensures that the engine remains within safe operating parameters, allowing it to function efficiently even under the extra load that descending hills often creates.