Jeep JK undercarriage rattle

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Jeep JK undercarriage rattleAny Jeep Wrangler owner have experienced weird noises their vehicle makes occasionally. We all realize that Jeeps are not really known for comfort and refinement. They are made for offroading and that’s where they shine, however daily driving, although fun, might make you go insane if you listen to every little unexplained noise your Jeep makes. Some of those noises are due to Wrangler’s shape, resulting in terrible aerodynamics. If you take the top off and install it back without making sure all the seals are perfectly aligned, you will experience loud wind noise. If you upgrade your front bumper or the fenders, you’ll increase drag and the noise will become even louder. Larger, more aggressive tires can be very noisy on asphalt. During daily driving you will most likely hear some squeaking inside the cabin, from the doors or seats for example. There might sometimes be some whining sounds coming from behind the dashboard.

Many of us driving Jeep Wranglers learned to react to all these noises by saying “It’s a Jeep thing” and cranking up the music. As long as the Jeep still runs, it’s totally normal.
Any Jeep owner who installed upgrades to their vehicle, and wheels their rig once in a while, accepts the fact that sooner or later there will be some hard to identify noises or rattling coming from the Jeep’s undercarriage.
These noises could be occurring at different times. It could be while the Jeep is not moving and simply idling, while you go over speed bumps or potholes, or when you’re braking.
Determining the source of the noise depends on this timing.
We all tend to expect the worse, but sometimes quick inspection of the undercarriage will reveal the culprit.
I would suggest that if the noise occurs while braking, you should obviously check your braking system. Inspect all brake rotors, calipers, anchor brackets (check the anti rattle clips), brake pads and of course the bolts securing all those parts. Putting the Jeep on jack stands and taking the wheels off will make this process much easier.
If the noise occurs while going over “obstacles” in the road, than it will most likely point to an issue with suspension. I would definitely check all the bolts for your shocks, control arms, sway bar links, track bars and drag links. You can find suspension torque specs here.
Noise or rattling occurring during idling will most likely be caused by a loose part of the exhaust system. There are of course other possible causes, like loose bolts or nuts in your driveshaft (more likely however to make noise while your Jeep is moving), or motor mount or transmission mount rubber dampeners deteriorating, however the noise would most likely be accompanied by vibrations you could feel when sitting in the driver seat.
Provided there is no vibrations, I would always inspect the exhaust first.

This post is meant as a quick guide to inspecting your vehicle’s exhaust system in order to locate the source of a Jeep Wrangler JK undercarriage rattle. I put this post together after experiencing rattling coming from underneath my own Jeep. In my case the noise would only occur while idling, after a cold start and only after putting my Jeep in reverse. It drove me crazy for few days, but I was finally able to locate and fix the problem. For me it was a broken spot weld on the crossover pipe heat shield, as well as a rear clamp which appeared tight however it wasn’t and it allowed the exhaust pipe to vibrate.

When it comes to the exhaust system, the most common cause of a rattle is the heat shields becoming loose, due to rocks hitting them, weak welds or corrosion. Your driving style and your climate will have a big impact on the shape of your exhaust system.

Remember: Let the exhaust system cool down before touching anything.

You can perform the inspection without any tools, however a screwdriver, mallet or a hammer might be useful. You will need few wrenches or sockets and possibly a hose clamp or two, in order to fix the problem. If you determine that the bolts securing heat shield above your muffler are rusted and the shield is loose, you will need few large washers and small u-bolts.

Disclaimer: Like I always mention I am not a professional mechanic, I just try to do as much work on my Jeep as possible. It helps me learn more about my vehicle and save some money that can be spent on parts and upgrades.
I take no responsibility for any injury or breakage which might occur if you decide to follow these steps. You have to decide if you’re comfortable working on your Jeep. If you’re not, please have a professional complete this project for you.

 

Parts and tools needed:

1. Ball Peen Hammer or Dead Blow Hammer

2. Slotted Screwdriver

3. 3/8-Inch Drive Deep Socket Set, Metric

4. 3/8″ Drive Ratchet

5. Combination Wrench Set, Metric

6. Hose Clamps

7. Cable Clip Clamps and Washers

 

Procedure:

Carefully inspect the entire length of your Jeep’s exhaust system, paying especially close attention to all the heat shields.

Jeep JK undercarriage rattle

 

Check the shield attached to the catalytic converter on the passenger side.

Jeep Wrangler JK undercarriage rattle

 

Check the shield attached to the catalytic converter on the driver side.

Jeep JK undercarriage rattle

 

Make sure that the bolts connecting the y-pipe on the passenger side are tight.

Jeep Wrangler JK undercarriage rattle

 

Make sure that the bolts connecting the loop pipe to the y-pipe on the driver side are tight.

Jeep JK undercarriage rattle

 

Check the spot welds on your exhaust crossover pipe heat shield. There should be two welds on the front side.

Jeep Wrangler JK undercarriage rattle

 

Check the two spot welds on the back side of your exhaust crossover pipe heat shield.

Jeep JK undercarriage rattle

 

The easiest solution to fix broken spot welds here is to install two 2″ hose clamps and tighten really well.

Jeep Wrangler JK undercarriage rattle

 

Make sure the exhaust clamp behind the y-pipe is really tight.

Jeep JK undercarriage rattle

 

Inspect the condition of the resonator. Make sure it does not come in contact with other parts, and that the hangers and the isolators supporting the exhaust are in good shape.

Jeep Wrangler JK undercarriage rattle

 

Make sure the exhaust clamp above the rear axle is really tight.

Jeep JK undercarriage rattle

 

Inspect all other exhaust clamps, if you have an aftermarket muffler or the entire exhaust system.

Jeep Wrangler JK undercarriage rattle

 

Inspect driver side bolts securing the heat shield above the muffler. These bolts tend to rust out (due to galvanic corrosion – steel washers in contact with aluminum shield, with salty water present), causing the heat shield to become loose.

Jeep JK undercarriage rattle

 

Inspect the passenger side bolts securing the heat shield above the muffler.

Jeep Wrangler JK undercarriage rattle

 

Hopefully you’re able to locate the source of your Jeep’s undercarriage rattle and fix it, restoring your peace of mind.

 

If you have any questions or suggestions, feel free to comment below.

 

 

November 17, 2019 |

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