What is Piston Slap in a Car Engine?
Introduction
Piston slap is a noise that can be heard from a car engine when the piston is loose in the cylinder bore. It is caused by the piston hitting the sides of the cylinder bore as it moves up and down. Piston slap is most noticeable at idle and low engine speeds, but it can also be heard at higher speeds if the piston is loose enough.
Causes of Piston Slap
There are a number of things that can cause piston slap, including:
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Symptoms of Piston Slap
The most common symptom of piston slap is a knocking noise from the engine. The noise may be louder at idle and low engine speeds, but it can also be heard at higher speeds if the piston is loose enough. Other symptoms of piston slap can include:
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Diagnosis of Piston Slap
Piston slap can be diagnosed by a mechanic by listening to the engine for the characteristic knocking noise. The mechanic may also use a stethoscope to listen for the noise more closely. In some cases, the mechanic may need to remove the engine head to inspect the piston and cylinder bore for damage.
Treatment of Piston Slap
The treatment for piston slap depends on the cause of the problem. If the piston rings are worn, they will need to be replaced. If the cylinder bores are worn, they may need to be bored out and fitted with new pistons. If the piston-to-cylinder bore clearance is incorrect, the piston will need to be replaced with a new piston that has the correct clearance. If the piston pins are loose, they will need to be replaced. If the connecting rods are bent, they will need to be replaced.
Prevention of Piston Slap
There are a number of things that can be done to prevent piston slap, including:
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Conclusion
Piston slap is a noise that can be heard from a car engine when the piston is loose in the cylinder bore. It is caused by the piston hitting the sides of the cylinder bore as it moves up and down. Piston slap is most noticeable at idle and low engine speeds, but it can also be heard at higher speeds if the piston is loose enough. There are a number of things that can cause piston slap, including worn piston rings, worn cylinder bores, incorrect piston-to-cylinder bore clearance, loose piston pins, and bent connecting rods. The treatment for piston slap depends on the cause of the problem.
