How to Solve the Piston Slap Issue in Volkswagen Bora?
2 Answers
When the car starts and knocking sounds occur in low-temperature environments, but disappear as the temperature rises, this type of piston slap can be temporarily left untreated. If the knocking sound not only persists but becomes more pronounced, the owner should avoid high-speed driving, promptly stop to inspect, and prevent traffic accidents. If severe cylinder ovality, scoring, or excessive clearance between the piston and cylinder is found, replacement is necessary. Replace the cylinder liner, piston, and piston rings. If connecting rod deformation is detected, replacement is recommended.
My previous Bora also had knocking sounds. At first, I thought it was a fuel quality issue, so I tried switching to 95-octane gasoline but it didn't help. It turned out the spark plugs were old. I bought new ones and replaced them myself, which solved the problem. I recommend starting with simple checks: inspect the spark plug condition and gap. If there's excessive carbon buildup, adding fuel system cleaner might help. Ignition system failures like aging high-voltage wires could also be the cause. If DIY doesn't work, go straight to a professional shop for diagnosis and tuning. Avoid aggressive driving when the engine is under heavy load to alleviate the issue. Safety first—don't delay repairs to prevent engine damage.
