How to get rid of rattles in the trunk

There’s nothing in this world that can annoy me more than a noisy car. I almost give up on my old Chevy today when it started rattling again. I really can’t handle the stress caused by that annoying sound. So when I got home, I phoned my brother to come to my place and fix the not-so-cool car. His name is Rick and he owns the local auto shop in our small town.

While he is fixing my car, I ask him for some simple steps on how to handle this kind of issue with my auto. My brother is a frustrated teacher and he told me a lot of things (I almost don’t understand) with trunk rattling and I’m happy to share it with you.

First, you got to understand that trunk rattle is most often caused by a deteriorated seal on your trunk lid or in the inner lining of your trunk that seals against the trunk lid. With a deteriorated seal, the trunk begins to vibrate during normal driving. As it vibrates, it makes contact with the surrounding metal on the body of the vehicle. While annoying, trunk rattle is not a serious mechanical or structural problem. However, you may want to fix it so that you can enjoy a quiet drive. I think you all agree with me that a nice quiet drive to work will set the right mode to conquer the day.

As your car gets older and their miles increase, rattles can develop in the interior as a result of being driven over bumps and rough pavement. What was once a nice, quiet, rattle-free car can become a noisy, annoying vehicle as interior panels squeak and rattle. Rattles are usually caused by missing or loose screws and clips that hold interior panels in place.

Mostly, trunk rattling can be found in rubber vent flaps on the sides (behind the trunk liner), 3rd Brake light and wires inside wing, and license plate frames. License plates rattle a lot. Plastic parts/panels, A-pillars and hoodliners rattle.You would have play some bass & press on things to see if the rattle gets quiet in that spot because different cars are going to have different sources of rattles.

My brother simplified that rattling is two hard things whacking against each other, so why not just put something soft in between those hard things? Dynamat etc adds mass so that it’s harder for the hard things to vibrate. This is called damping. Damping helps eliminate resonant frequencies so that just the speaker cone, and not the metal car panel, is producing sound. Therefore the sound is cleaner. Dynamat is a damping product, and the 70-80% or whatever reduction in rattling is a side-effect of damping. If you press around on your panels to see where exactly things are rattling, you can save a ton of time, effort and money by using some foam tape rather than dynamat. Your rattles will be down to zero, it’s a lot easier to apply, and your whole vehicle can be done for less than 10 bucks worth of foam tape. You can use it behind your license plate too. Just put strips of it between the hard things that are rattling against each other.

You must buy sound deadening material and basically surround the space between your trunk lid and the bottom with the material. Mind you it is still going to vibrate so you are going to have to pay attention to the key areas that are rattling. Perhaps you will even have to tighten the screws and lubricate the bolts with oil.

Here’s the simple procedure on how to solve this concern with your car:

1. Determine the source of the rattle while driving.

2. Park the vehicle and verify that all of the screws that hold the interior panels and trim are installed and tight around the area where the rattle is coming from. Check all of the panels, including the door panels, foot well kick panels, rear interior panels and the panels located in the trunk or around the rear hatch if it is a hatchback.

3. Open the trunk and inspect the water drain valleys as well as the trunk lid. Look for any damage or deterioration of the trunk seals.

4. Spray the all-purpose cleaner in the trunk valleys and on the underside of the trunk lid, and thoroughly clean all areas where the trunk lid contacts the body of the vehicle. Make sure that there is no dirt or debris in the drain valley or the underside of the trunk lid.

5. Apply a bead of urethane molding to the underside of the trunk lid or to the drain valley at every point where there are signs of seal damage or deterioration.

6. Tighten the screws with the appropriate screwdriver (flat head or Phillips) and replace any missing screws with new screws. If your interior uses clips to hold panels on, make sure all of the clips are present and not broken. Replace any clips that are missing or broken.

7. Install sound deadening material. Cars are manufactured with sound deadening, some more than others, depending on the manufacturer. A trick that many stereo installers use is installing more sound deadening behind interior panels that usually do not have sound deadening.

8. Remove the interior panels where you think the source of the rattle is coming from. Cut the sound deadening to fit behind the panel with scissors or shears. Spray adhesive on the back of the sound deadening or use brush-on adhesive. Put the sound deadening in place and press it firmly on. Replace the interior panel over the sound deadening, ensuring that none of it is exposed past the edges of the interior panels. You can also add sound deadening behind all of the interior panels to make the interior more quiet and solid feeling.

9. Allow the urethane to dry completely, close the trunk and turn on the vehicle. Verify that the trunk is sealed and no longer rattling.

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