Jeep Cerokee and Wrangler Piston Slap Problem

Jeep Cherokee And Wrangler Piston Slap Problem [Solved]

Lots of discussions going on about the Jeep Cherokee and Wrangler slapping noise. Especially, when unusual noises coming from the engine, most car enthusiasts take it more than seriously. 

So, what causes Jeep Cherokee and Wrangler piston slap problems?

The increased clearance between the piston and cylinder bore is the main cause of Jeep Cherokee and Wrangler piston slap problems. Also, the worn cylinder or inadequate oil flow to the rocker’s arm can cause this issue as well. To get rid of the slapping noise you must first find out the reason.

This is what you can know at a glance. For detailed discussion read further.

What Causes Jeep Cherokee And Wrangler Piston Slapping Noises?

Slapping noise in the Jeep Cherokee and Wrangler is typically caused by identical reasons.  Let’s have a quick look at the table below for a primary idea. 

Increased clearance between piston and cylinder bore Do a compression testReplace the piston
Inadequate oil flow to the rocker’s armScan your vehicle by OBD scannerUnclog oil filter

As you now have the basic idea, let’s begin the brief discussion.

Reason 1: Increased Clearance Between Piston And Cylinder Bore

Increased Clearance Between Piston And Cylinder Bore
Source: Free Study ASE Guide

Back-and-forth movement of the piston within the cylinder, increased clearance between the piston and cylinder bore can cause slapping noises. Due to this, the piston can hit cylinder walls harder, resulting in slapping noises.

Furthermore, increased clearance can also result in increased vibration of the piston, contributing to the slapping sound. This reason is, however, uniform for both the Jeep 3.7-liter and 4.0-liter engines.

Diagnosis: Check the Compression of The Cylinder

If the clearance increases between the piston and cylinder bore, compression will reduce. You can simply check the compression of the cylinder to check if the clearance increased or not. To do the compression test, arrange the following tools.

  • A compression tester gauge 
  • A spark plug socket
  • Remote engine starter

When you’ve got all these tools, follow the steps below. 

Safety precaution: First, disconnect the fuel flow removing the fuel injector fuse. Pull the central wire off to disable the ignition and high-tension electricity.

Step 1: Remove the spark plug

Before removing the spark plug wire by hand. Then remove the spark plug by using the appropriate spark plug socket. You can also check out when should you replace the spark plug.

Step 2: Attach the compression tester gauge into the spark plug hole

In this step you need to attach the compression tester gauge with the spark plug hole. Then the finger tightens it. 

Step 3:Crank the engine

Now, you need to start the engine by using a remote starter. It is applicable to the modern car. Older models manufactured before the mid-90s may require another person to crank and start the engine. Finally, note the reading. 

Test the compression of each cylinder by following the same guideline. Each cylinder of the Jeep Cherokee or Wrangler 4.0L engine must have more than 100 PSI compression.  If you find the average PSI below this, the clearance is increased. 

Solution: Replace The Piston/Rebuilt Engine

When you know Jeep Cherokee or Wrangler piston slap for increased clearance between the cylinder bore and piston, you may either need to replace the piston or cylinder.  

You can determine the worn cylinder by measuring the cylinder bore diameter with a bore gauge. A 58.74mm (2 5/16 in.) diameter measurement should be taken from the top of the bore of the cylinder 

If clearance increases for the worn cylinder then you may need to rebuild the engine or replace the cylinder. Similarly, if a worn-out piston or piston ring occurs, you need to replace the piston.

Replacing the piston is a critical task and needs high technical knowledge. So, we recommend visiting a professional workshop for the service. 

If you are a DIY enthusiast, follow the instructions in the video below to replace the piston. 

Reason 2: Inadequate Oil Flow To The Rocker’s Arm

Inadequate oil flow to the rocker’s arm can cause a slapping noise due to the lack of lubrication on the moving parts. In an engine without sufficient lubrication, the crankshaft rocker arm may come into contact with the metal parts and cause a slapping noise.

A clogged oil filter can contribute to this factor. To prevent further engine damage, it is important to diagnose and fix the issue as soon as possible.

Additionally, inadequate oil flow may also cause engine misfires.

Diagnostic: OBD II Check and Replace or Repair Necessary Parts

You need to check the trouble code using OBD II if reason 1 does not apply to your Jeep Cherokee or Wrangler. 

The process of scanning the vehicle is simple. You simply need to connect the OBD II scanner to the Jeep OBD port, which is typically located under the dashboard. And then follow the prompt to scan your Jeep.

The P0524 code indicates that there is not enough oil in the crankshaft rocker arm if you scan by OBD. In this case, you need to refill the engine oil. 

Solution: Unclog Oil Filter

For a visual guide to unclogging the oil filter see the video below. 

How Serious Jeep Cherokee And Wrangler Piston Slap Is?

If you consider the instant impact, the slapping noise isn’t too serious. But in the long run, this issue can wear out the piston and the cylinder bore. 

You can still drive with a slapping noise in the piston. But for a performance enthusiast, it’s really annoying and uncomfortable. This is why it’s advisable to pay attention to slapping noise. If you encounter this issue, get rid of it as soon as possible. 

If you continue driving with the piston slapping, it may cause further engine problems like piston ring wear down, oil leakage, and excessive emission. 

So, after encountering the issue, get it fixed as early as possible.

Frequently Asked Questions (FAQs):

What Causes Pistons To Overheat?

A malfunctioning cooling system causes piston overheating. Apart from that, broken piston rings or insufficient clearance between the piston rings can also cause piston overheating. Additionally, bypassed combustion gas and mistiming valves can be the reason for piston overheating.

Can You Spray Brake Cleaner On The Piston?

Yes, you can spray brake cleaner on the piston moderately.  Spraying brake cleaners can help you to penetrate dirt and clean contamination. It’ll also help you to remove the plastic blocks. 

Will Thicker Oil Stop Piston Slap?

No, thicker oil won’t stop piston slapping because worn rings cause the piston to hit the sides of the cylinder instead of moving smoothly. Thickened oil will not solve the problem, it will only temporarily conceal it. It is necessary to remove the pistons and replace the rings in order to stop the piston slap.


Well, this was all about the Jeep Cherokee and Wrangler piston slap problem. Hopefully, you’ve got the answer you were looking for. However, don’t delay getting the piston slap fixed as soon as you start encountering the issue. 

Thanks for your patience!

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