What is a common symptom of incorrect tappet adjustments?

Excessive noise from the engine is a common symptom of incorrect tappet adjustments due to the vital role tappets play in controlling the opening and closing of the engine's valves. When the tappets are out of adjustment, they can create a situation where the clearance between the tappet and the valve is not optimal. This improper clearance can lead to increased friction and impact between components, resulting in a ticking or tapping sound as the valve train operates. This noise typically indicates that the engine components are not functioning harmoniously, which can lead to further damage if not addressed.

In contrast, while symptoms like engine overheating, idling too slow, or reduced acceleration may arise from various mechanical or tuning issues, they are not directly linked to tappet adjustments. Engine overheating can stem from coolant system failures or other problems like a faulty thermostat, while slow idling or reduced acceleration could indicate issues with fuel delivery, ignition problems, or air intake restrictions. Therefore, the presence of excessive noise serves as a more direct indicator of improper tappet settings.