How to Fix Piston Slap

You might wonder what piston slap is and how you can fix it. Piston slap occurs when a car’s engine misfires, which causes the pistons to vibrate or move too quickly in the cylinder. This typically happens because of excess fuel or spark plug problems.

How To Fix Piston Slap

If left unchecked, this condition will increase wear on your engine and lead to more costly repairs down the line. How to fix piston slap? You can address this problem in several ways without taking your car to an auto repair shop!

Summary: In this blog post, we learn how to fix a piston slap. The piston slap is when the piston in a engine or motor suddenly slams into the cylinder head, causing damage to the engine. This can be a very costly repair, so it’s important to know how to fix it. To fix a piston slap, you first need to determine the cause. Often, the cause is a poorly fitted piston. In this case, you’ll need to replace the piston. If the piston slap is due to a defect in the engine or motor, you’ll need to replace the engine or motor.

What is Piston Slap?

Piston slap is a condition that can occur when an engine is running. It is caused by the expansion and contraction of the engine during each stroke. This can create sound waves that are amplified by the metal surfaces in the engine block and cylinder head. Piston slaps can be minimized with some preventive maintenance steps or more drastic measures if they persist.

Fixing piston slap may include things like adding an acoustic blanket around the inner surface of your exhaust manifold where it attaches to your headers, installing thicker gaskets between parts that make contact (e.g., water pump), tightening bolts/studs at exhaust ports where you’ve previously loosened them for performance purposes, or switching from flat top to dish head spark plugs.

What Causes a Piston Slap?

A piston slap is a sound caused by your engine’s valves moving back and forth. It’s not harmful, but it can be annoying and may indicate an issue with one or more cylinders in your vehicle. If you notice piston slap accelerating from idle to higher speeds, this could mean there are faults in the pistons, such as low compression or worn bearings.

The best way to handle piston slaps is prevention, so check for leaks around seals and gaskets since these usually cause the problem. Be aware that if you have bad airflow through your intake system, which means less oxygen going into combustion chambers, gasoline will burn inefficiently, creating oil deposits on top of the pistons.

Required Tools

  • Phillips screwdriver
  • Ratchet extension
  • Socket wrench
  • Tap and die set

Instructions: How to Fix Piston Slap

Step One: Remove the intake and exhaust manifolds from the engine and examine them for signs of overheating.

Remove the Intake and Exhaust Manifolds From the Engine

Step Two: If you see corrosion, cracks, or broken welds on your manifolds, replace them with new ones. You can also use a high-temperature exhaust manifold paint to protect against further damage from heat.

Step Three: Inspect and clean all joints at connections, including the manifolds, exhaust pipe, and clamps.

Step Four: Tighten or replace clamp bolts that may have become loose during installation.

Step Five: Consider upgrading to flat top plugs if you drive your engine hard for extended periods of time, specifically when using high octane fuel with a turbocharger or nitrous oxide system.

Step Six: Replace the plugs with ones with a higher heat rating and an electrode design to withstand temperatures above 1200 degrees Fahrenheit for extended periods.

Step Seven: Replace the spark plugs with ones that are specifically designed for racing engines.

Step Eight: Install a new exhaust system, such as an aftermarket high-performance unit or one designed to reduce noise pollution.

Step Nine: Change your engine oil and filter at least once per year, ideally every six months, to match driving habits; this will help prevent the buildup of sludge and other contaminants in your engine.

Step Ten: Purchase a high-performance air filter, such as K&N or Performance Intake Systems.

Step Eleven: Install an underdrive crank pulley kit to reduce the pressure on your crankshaft and bearings while increasing fuel economy by up to 15% at highway speeds.

Step Twelve: Install a performance ignition system, like MSD Atomic or Accel Supercoil to get more power.

Prevent Piston Slap from Happening

  1. One of the ways is by adding a weight on top of the rod. When you do this, it will not vibrate as much, and thus, no noise will be produced. You must ensure the weights are heavy enough to make the rod stop vibrating.Prevent Piston Slap From Happening
  2. Piston slapping is a condition that can happen in engines when they are running, and it’s often described as metal-to-metal contact. This happens because of an imbalance between engine parts, which causes one to strike the other.
  3. Most of the time, this noise will happen when an engine is idle. This condition can be prevented by adding a balance weight on top of the rod to reduce vibration and prevent metal-to-metal contact.
  4. When you do this, the noise will be less likely to happen. You should ensure that the weight is heavy enough to stop vibration and thus keep metal-to-metal contact from happening.
  5. Check your air filter for obstruction and replace it if necessary. If these are not the problem, you can also try to have a mechanic look at your engine or get a tune-up done, which may rectify the problem.

Precautions To Take

  1. Make sure the engine is completely shut off before touching anything
  2. Wear safety glasses to protect your eyes from metal fragments that may fly out of the cylinder head
  3. Remove spark plugs and mark them so you know which one goes where. You’ll also need a piece of paper.
  4. A clean rag for wiping away any oil residue on tools. Using gloves when handling dirty parts such as pistons is also important.
  5. Gloves are necessary when removing old gaskets and O rings because they can cause an allergic reaction if touched.

Frequently Asked Questions on How To Fix Piston Slap

How Do You Overcome Piston Slap?

Fixing piston slap is easy with the right tools. You will need a new piston and rings, valve stem seals, compression seal oil (if necessary), a socket wrench set, deep-well sockets for removing individual nuts from the engine block, and other types of wrenches to tighten the nuts.

How Do You Overcome Piston Slap

How Is Piston Slap Diagnosed?

Diagnosing piston slap is usually a job for an experienced mechanic who will be able to see the telltale signs. If your engine has been overheated or as it cools, you may hear the pistons slapping against the cylinder walls, which can also create leaks in the exhaust system.

If you’re hearing the sound of a “clanking” in your engine that’s not coming from the exhaust system, it could be a piston slap. It sounds like it isn’t much wrong with your pistons and rings, so we’ll need to check valves next.

How Does Piston Slap Become Permanent?

If the engine is allowed to continue at high speeds, a previous event may have damaged your pistons and rings in such a way as to make them permanently “slapped.” You could also accidentally over-rev an engine by trying to get more power out of it with too much timing advance or turbo boost, which would cause permanent damage.

Sometimes, heat cracks can occur during rapid expansion and contraction cycles when parts are made from aluminum alloys like 6061T6511 (aluminum). When they contract again after being heated, they will have permanent stresses, which could lead to piston slap.

How Much Does It Cost to Fix Pistons?

Piston slap is rarely a serious concern and can typically be fixed by replacing the offending piston rings. However, suppose other damage concerns have been noticed, such as overheating or leaking fluids. In that case, they will also need to be addressed so it would not cost less than several hundred dollars for all necessary repairs.

Piston Slap is Rarely a Serious Concern

Does Piston Slap Go Away When Engine Is Warm?

Piston slap is a problem that will get worse as engine heat rises. The sound of the piston going against the cylinder wall becomes more pronounced with higher temperatures which means it’s an even greater risk when operating in high-heat environments like hot climates or during heavy traffic on busy roads where your vehicle can overheat quickly.


If you have been experiencing engine problems, it’s time to take a closer look at your pistons. Piston slap is often the culprit and can be fixed with these tips. The following guide will help you learn how to fix the piston slap so you can get back on the road in no time!

You may also read: How Much Does It Cost To Fix A Rod Knock

Louis Wein

Louis Wein

Louis has always been fascinated by cars. He loves the way they look, the sound of the engine, and how they make him feel when he's driving. He is always keen to learn more about different mechanics of cars and how the engine contributes to other aspects of the car. As an automotive technician with over 10 years of experience, he knew how they worked and loved taking them apart to see how they went back together. He was especially interested in the mechanics of combustion engines and loved finding ways to make them more efficient. He loves to work on cars and help people keep their vehicles running smoothly. As a senior editor, he enjoys contributing to Diy quickly because it allows him to share his knowledge and expertise with others.

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