Three of the most common causes of metal rattling noises that come from under the car are as follows:
- loose exhaust hangers and clamps
- failed catalytic converter
- a damaged heat shield
- a bad or hanging splash shield
Therefore, if you are hearing metal rattling noises under your vehicle, you may want to start troubleshooting this problem by considering these first.
As your vehicle and its components begin to grow older, the exhaust system may begin to corrode and deteriorate. Unfortunately, whenever this happens, the joints that keep things in place may shake, knock and rattle because they are too loose.
A failed Catalytic Converter
Another common cause of a vehicle making rattling metal noise under the vehicle is a failed catalytic converter. Because these components can fail due to overheating, the pieces in their internal structure may start to break away.
Additionally, once this happens, the driver and their passengers will most likely hear noises that sound like marbles rolling vigorously around inside of a metal can.
Damaged Heat Shield
To protect the exhaust manifold from damage, car manufacturers place heat shields wrapped around the exhaust manifold. These shields are designed to redirect the heat out of the engine in order to protect the most vulnerable components in the engine.
However, if the heat shields are damaged, they cannot do the function that they are made for. For instance, if the heat shield is damaged, the components of the exhaust system will separate themselves from its mount.
These separated parts will also cause the loud rattling that people hear as they drive.
Bad Engine Splash Shield
The role of a splash shield is to protect important engine parts that are located at the bottom from stuff that is on the road that could damage them, like rocks. The oil pan is a great example.
The splash shield is made from plastic and metal. if the bolts are damaged, the shield could hang or you can hear other noises caused by this issue.
How can I fix this metal rattling noise?
To fix a metal rattling noise that is coming from under the car, it is important that you know the root cause first. Because the metal rattling noise is commonly caused by 1 of 3 things, a mechanic may need to inspect the vehicle to pinpoint the exact reason prior to determining the fix.
With that being said, here is how to fix these problems based on the root cause of the problems listed above.
Fix Loose Exhaust
To repair a loose exhaust, you need to know the extent of the damage. For instance, to fix a loose exhaust, a professional mechanic may only need to perform minor welding repairs on the muffler. Or, they need to weld a new muffler.
Repair or replace the catalytic converter
When a catalytic converter fails, it may need to be replaced. However, before you go this extra mile, there are at least 2 other options that you may want to try before paying out your hard-earned money to replace these parts.
- Clean it thoroughly
- Flush it
- Replace it
Replace the splash shield
Fortunately, it’s easy to detect a problem with the engine splash shield. If the bolts are the issue you can replace them to avoid other costs. But if the shield is damaged, just replace it.
When the heat shield has been compromised due to rust or other factors, there are 2 things that you can do to correct the damage. Based on the condition of the heat shield, you may have the option of reattaching or replacing it with a new one.
How much does it cost to fix these issues?
The cost of fixing rattling noises from under the car usually varies based on the root cause. For example, here are a few examples of the average cost that you may expect to pay.
For Exhaust Repairs
- The average cost of a minor welding job- is between $30 and $500
- The average cost of welding a new muffler is between $75 and $750
Catalytic Converter Failure Replacement Costs
The average cost of replacing a Catalytic Converter – is between $400 and $2,000 (parts only).
Replacing the Heat Shields
The average cost of a heat shield replacement can range from $150 to about $300.
Repairing or replacing the splash shield
The costs for replacing damaged bolts can vary depending on the type of shield and on the car make and model you can expect to pay from $30 to $100.
Replacing the splash shield can vary depending on the material, whether plastic or metal and depending on the car brand. Usually, the price of an engine splash shield can vary between $40 and $150, and the labor can cost up to $70.
If you hear metal rattling noises coming from under your car, you need to know the exact cause before you continue to drive. Since this problem may be due to the causes listed above, you may need a professional to identify the root cause and repair it as soon as possible.
Based on the situation and surrounding circumstances, an experienced mechanic can make the appropriate repairs to stop the metal rattling under your vehicle.