What Causes Abnormal Noise in the Santana Engine?

[VonKevin]

Here are the reasons for abnormal noise in the Santana engine: Excessive wear of the camshaft causing tappet jumping during operation; excessive valve clearance due to wear or improper adjustment of the valve stem end, adjusting screw, or rocker arm, leading to collisions between the rocker arm head and the valve top in overhead valve configurations; excessive carbon buildup in the valve guide; detachment of the valve spring seat; or damage to the hydraulic tappet or tappet barrel. If the abnormal noise occurs momentarily during startup and disappears at idle after the engine starts, the issue is mostly caused by faulty carbon brushes inside the starter motor. The working principle of the engine involves the electromagnet activating after power is supplied, engaging the starter motor gear with the engine flywheel to rotate together, thereby starting the engine. Once the engine starts, the gear quickly retracts. The noise occurs when the starter motor gear fails to retract promptly, causing gear grinding with the flywheel. Therefore, the starter motor needs inspection. To reduce the likelihood of this issue, avoid holding the ignition key in the start position for more than 5 seconds when starting the vehicle—release the key quickly after turning it to allow automatic retraction. If the abnormal noise persists at idle after the engine starts, the issue is likely due to excessive clearance between the hydraulic tappets and valves inside the engine cylinder head. As the vehicle accumulates mileage and ages, both the valves and hydraulic tappets experience wear. Excessive clearance results in a "clicking" noise. Resolving this issue requires disassembling the cylinder head to replace these two components. To delay the onset of this problem, change the engine oil regularly and avoid overusing it, as degraded lubrication accelerates wear on the valves and hydraulic tappets.