Obvious Signs (requiring visual inspection):
* Visual Inspection: The easiest way, if accessible, is to remove the valve cover(s) and visually inspect the rocker arms. Look for any obvious cracks, broken components, or loose mounting bolts. Loose rocker arms may be visibly tilted or out of position.
* Oil Leak: A significant oil leak around the valve cover is possible if a rocker arm is damaged and leaking oil.
Indirect Signs (inferring a problem):
* Loud Ticking or Knocking Noise: This is the most common symptom. A loose or broken rocker arm will cause a distinctive metallic ticking or knocking sound that changes with engine RPM. The sound's location might help pinpoint the affected cylinder bank.
* Loss of Engine Power/Performance: If a rocker arm is completely broken or severely loose, it will prevent the valve from operating correctly, leading to a significant loss of power, misfires, rough idling, or even a complete engine stall.
* Check Engine Light: A malfunctioning rocker arm will likely trigger the check engine light. An OBD-II scanner can retrieve diagnostic trouble codes (DTCs) which may indicate a misfire on a specific cylinder, strongly suggesting a valve train problem.
* Exhaust Smoke: If the valve is not closing properly due to a rocker arm failure, it might lead to excessive exhaust smoke (depending on the severity and which valve is affected).
* Low Compression Test: A compression test on individual cylinders can reveal low compression in a cylinder affected by a broken or loose rocker arm. A significant drop in compression compared to other cylinders is a strong indicator.
Important Note: It's crucial to locate the source of the problem and repair it promptly. A broken or loose rocker arm can cause severe internal engine damage if the valve is not functioning correctly. Driving with a faulty rocker arm could bend a valve, damage the piston, or cause catastrophic engine failure. If you suspect a problem, have a mechanic diagnose and repair the issue as soon as possible.
