CAR RATTLING NOISES BOTHERING YOU? 33 POSSIBLE CAUSES AND HOW TO FIX THEM
A car is an extremely complicated machine. It has many different systems that interact with each other. Each of these vehicle systems has its own set of moving parts. These systems are responsible for:
- Providing power inside your engine
- Circulating the fluids that cool and lubricate those engine parts
- Cleaning the exhaust and removing it from your car
- Transmitting the engine’s power to the wheels
- Helping it to ride and handle well
- Stopping it
- Keeping you comfortable inside your vehicle as you drive it
When your car was new, everything worked very well. Driving was a smooth, quiet experience. But that peaceful, easy feeling can change as time passes and the miles add up. Metal parts wear, tight clearances between parts widen, plastic and rubber components deteriorate and fail, and fasteners like nuts and bolts loosen.
When that happens, you may hear a variety of different rattling noises. They can come from many places within your vehicle as it ages. You may hear these rattling noises when you start your car, when you accelerate or cruise down the road, when you hit a bump, when your engine is idling, and when you step on the brakes.
Rattling noises are the automotive equivalent of the aches and pains suffered by many people as they get older. Some of them are simply annoying, but others could have serious consequences if not dealt with promptly.
Join us for an insider’s view of how to figure out where these rattling noises are coming from, how serious they are, whether it’s safe to drive with a rattling noise, how to fix it, what it costs, and whether it’s worth fixing.
How can I tell where a rattling noise is coming from?
There are quite a few places within your car where a rattling noise can be coming from. To help you narrow it down, we will divide your vehicle into four zones, and then list the possible sources of the rattling noise you may be hearing from each zone. They are:
What’s making a rattling noise under my hood?
Under the hood of your car lives your engine, your transmission, and many other components that support the operation of these two major elements of your drivetrain. There are a great number of systems and subsystems located here, all with moving parts that can produce rattling noises under the right (or actually the wrong) circumstances.
The moving parts inside your engine
You have a great many moving parts inside your engine. As they wear, you may hear rattling noises from a variety of sources:
Timing belt or chain noise
The timing belt or chain in your engine connects the crankshaft to the camshaft, for proper operation of the valve train. Modern overhead cam engines have very long chains and belts, and they use hydraulic tensioners to keep the chain taut. Over time, the nylon chain guides wear and the tensioners can’t manage the slack in the chain or belt. You may hear a rattling noise made by the chain or belt whipping around, with insufficient tension, inside the timing chain cover. This noise will rise and fall with the engine RPMs.
The fix: You will need to replace the hydraulic tensioners and the chain guides. If you have a timing belt, check the wear. Replace it if you are near the prescribed replacement interval. This issue must be dealt with immediately – if the chain/belt breaks or slips, your engine could be destroyed. Due to the large amount of labor involved, repairing this problem will be expensive.
Connecting rod knock
The connecting rods convert the up-and-down motion of the pistons to the rotary motion of the crankshaft. Rod knock noises are the result of wear from insufficient or dirty oil. This condition wears down the surfaces of the bearings, causing excessive clearances between the rods and the crankshaft.
The fix: The sound of knocking rods means that you will need major engine work. This will be very expensive. If you don’t have it fixed, these moving parts can fail and destroy your engine.
Do you have a high-mileage vehicle with a worn engine? If so, the pistons may fit very loosely in the cylinders. This can make itself known as a rattling noise during a cold start. The noise usually goes away, once that the pistons expand after the engine warms up.
The fix: You can solve the problem by replacing your worn pistons with oversize versions, but this is very expensive. If you have a high-mileage vehicle without much value, it is not worth doing. The good news? If you can put up with the noise, it probably won’t result in any other issues.
Valve train noise
Your engine’s valve train is driven by the camshaft. It opens and closes your engine’s valves, allowing fuel into the cylinders and letting the exhaust gases out. The valve lifters are the parts that make the valves open and close. If they get wear, get stuck, or go out of alignment, you may hear a rattling noise, particularly at low RPMs.
The fix: There are a few practical options here, depending on the type of lifter and the exact cause of the problem. Dirty oil that has not been changed often enough can be a factor, so change your oil as a first step and see if that helps. Possible repairs for this condition include adding a detergent additive if the lifters are coated with varnish and sticking, adjusting the valves and/or lifters, or replacing any defective lifters. The cost to repair this problem will depend on how serious it is – ask your mechanic for all of your options.
The things that are attached to your engine
Your engine has many mechanisms that are attached to it and driven by it. These components can produce rattling noises.
A defective water pump
The water pump is driven by your engine. It circulates coolant through your vehicle’s engine and heating system. If the bearings on the drive pulley fail, this can cause a rattling sound. A coolant leak may accompany this sound.
The fix: If the water pump pulley has excessive play, the pump needs replacement. This is a fairly easy fix that can prevent your engine from overheating. Don’t wait. It can cost several hundred dollars to replace your water pump, due to the significant amount of labor involved. If you want to keep driving your car, you don’t really have a choice.
A bad starter
The starter motor gets your engine started by cranking it. In the starter is a component called a Bendix, which connects it to the engine when starting it and disconnects the starter when it is done. The Bendix can be bad, preventing the starter from disengaging from the engine. This will make a rattling noise.
The fix: The starter motor should be replaced. A rebuilt starter will be reasonably priced, and it should come with a warranty. To go the lowest-cost route, you can get a used starter from an automotive recycler, but it will not have a warranty.
A worn-out drive belt
The rubber drive belts connect many of your engine-driven systems. These belts can eventually deteriorate from wear and the high temperatures under your hood. You may hear a rattling-like sound, made by a frayed or cracked belt as it flaps around inside the engine bay.
The fix: Simply replace the bad belt. It’s an inexpensive repair, whether you do it yourself or have a mechanic do it. If the belt breaks, you could lose alternator, air conditioning, and other important functions, which can lead to more expensive complications. Don’t wait!
A failed fan clutch
If the vehicle you drive has rear-wheel drive, with its engine mounted lengthwise, you may have a fan clutch that regulates the operation of an engine-mounted cooling fan. This fan clutch can go bad and produce a rattling noise. Other symptoms can include higher coolant temperatures or possibly overheating.
The fix: With the car shut off, you can check for excessive fan clutch play. Hold the fan and move it in and out. Also check whether the fan will turn in both directions. If it is bad, the fan clutch will need replacement. This is a relatively inexpensive repair that should be done immediately to eliminate the possibility of overheating your engine – which will not be an inexpensive repair!
A broken harmonic balancer
Your harmonic balancer is a counterweight used to reduce vibrations in your engine. It uses a rubber ring which can separate from the balancer, resulting in a rattling noise.
The fix: Replacement of the harmonic balancer. The part is not too expensive, but there is some labor involved in replacing it. Check with your mechanic for the cost of replacing it on your car.
Rattling noises caused by fuel or oil-based problems
Here are some fuel and oil-related rattling noises:
A pinging noise from low-octane fuel
To operate properly, your engine needs gasoline that has the correct octane rating. Should you hear a pinging or rattling sound when you accelerate, low-octane fuel could be causing it. This pinging (also known as pre-ignition or detonation) may also be the result of overheating, carbon deposits, incorrect ignition timing, or a bad knock sensor.
The fix: Try filling your gas tank with premium gasoline, drive it, then see if the problem goes away. If it doesn’t, you will need to have your mechanic figure out the exact cause. If you don’t get this fixed immediately, it could damage or destroy your engine! The extent of the repairs needed will determine the cost to fix it.
A low engine oil level
To lubricate its internal moving parts, your motor oil circulates throughout the engine. As your car ages, the engine can consume, burn, or leak oil. When the oil level gets too low, there can be a situation where air gets pumped through the engine, along with the reduced amount of oil that remains. This can produce a rattling noise from within the engine.
The fix: Immediately shut off the engine. Check your engine oil level by pulling out the dipstick, wiping it off with a paper towel, then reinserting and checking the level. Ideally, it should be between the two marks on the dipstick. If the level on the dipstick is low or non-existent, use the oil specified for your vehicle and fill it to the maximum level. If you are burning a lot of oil or have a major oil leak, the cause of the problem should be found and corrected right away. If it’s not, your engine will soon fail. The cost of repairs will depend on exactly what the cause is.
Some other rattling noises that come from under your hood
Even though the items listed above are the most common causes of rattling noises under your hood, there are other potential sources of rattling noises. These include:
- Under-hood heat shielding that comes loose on exhaust manifold or turbocharger
- Idler pulley that has worn out
- Cracked or loose accessory brackets
- Cracked flex plate between engine and transmission
- Crankshaft bearings that are worn
- Piston pins that are loose or worn
What’s making a rattling noise inside my car?
Today’s cars have many storage spaces placed throughout the vehicle. Most of the rattling noises that come from inside your car are the result of loose items moving around within these spaces as your car accelerates, brakes, or turns. Fortunately, most of these issues cost nothing to fix, except for a little of your time!
Noises from your trunk or luggage compartment
You are likely to hear these interior rattling noises from items the rear of the car. The sounds will be noticeable when you hit a pothole or make a sharp turn.
The fix: Take a close look inside your trunk or luggage compartment. Are you using it as a storage unit? All of those loose items can cause the noises you hear. They also add unnecessary weight to your vehicle, which can reduce your fuel economy. Remove them to eliminate the rattling noises. After that, check the area around your spare tire. Make sure that the tire, the jack, and any other loose items there are secured tightly, so that they can’t produce any rattling noises.
Once that you’ve done this, take your car for a drive on a bumpy, windy road. If rattling noises are still coming from the rear, have your mechanic check your car’s rear suspension – something could possibly be loose there. The exact nature of the problem, will determine the cost to fix it.
Noises from the console, glove compartment, and door pockets
Rattling noises from these areas will usually be heard when going around tight corners or hitting bumps.
The fix: Check for the sources of these noises in each of your car’s interior storage spaces. Do you see any bolts, nuts, or other items that can make these rattling noises when they roll around in there? Remove what you find and take a drive. If you stop hearing the rattling noises, you found the solution! If you still hear the noise, check again. See if the compartment covers are loose, or if any moving parts are out of alignment. Fix them if you can or ask your mechanic to take care of it the next time your car goes in for service.
Check for other interior noises
Almost anything in your interior that has moving parts may loosen up and make rattling noises. Check these other potential sources:
- Folding seats
- Open windows
- Luggage compartment covers on SUVs and hatchbacks
- Cup holders
The fix: Look for loose or missing hardware on these items. If you can’t fix them yourself, let your mechanic know about it.
What’s making a rattling noise under my car?
Let’s get into some possible causes of rattling noises that come from the underside of your vehicle. You may hear these when you hit a bump, when you start your car, when you drive at a steady speed, or even the entire time you are driving.
Heat shielding that is loose or rusted
Stricter emissions regulations have led to higher operating temperatures for engines and exhaust systems. This has created a need for robust heat shielding on exhaust components like mufflers, catalytic converters, and exhaust pipes. Thin metal heat shields are located between these exhaust components and the bottom of the vehicle. As your car gets older, they can rust out or become loose. These heat shields are a common source of rattling noises under your car.
The fix: Inspect your heat shields for corrosion and looseness. Retighten or replace them if necessary. The parts are not very expensive, and access is easy, once you get your car up on a lift.
A loose exhaust system
The exhaust system starts at your engine and ends at the rear end of your car. It consists of many parts, including the catalytic converter, the muffler, and pieces of exhaust pipe that move exhaust gases out of your vehicle. As you rack up the miles, these exhaust system parts wear and the joints between them get loose. This can create a rattling noise under your vehicle.
You may also hear an abnormally loud exhaust sound, which may appear to be coming from underneath your car, and not from the rear tailpipe. If you have a loose exhaust system, it may also rattle against the bottom of your car when you drive on a rough road.
The fix: Have your mechanic check your exhaust system checked by your mechanic or a local muffler shop. You could just need a clamp tightened, or a bad rubber hanger replaced. If the damage is more severe, you might have to replace a section of pipe that’s rusted, or you could need a new muffler. The costs can range from minimal to moderately expensive.
Whatever it is, you need to have it fixed right away. It’s a simple repair to have done. More important, you don’t want to pass out – or worse – because exhaust fumes got inside your car while you were driving.
A bad catalytic converter
Your catalytic converter is part of your emissions control system. It takes toxic gases and pollutants from your exhaust gas and converts them into harmless substances through a chemical reaction that happens inside of it. Catalytic converters are subject to damage, either from thermal shock or an impact with road debris. Parts of the ceramic inner structure can break off and cause a rattle. If the damage is severe, the noise can sound like shaking a box full of rocks. This condition can trigger a Check Engine Light on your dashboard, along with a trouble code in your car’s engine computer.
The fix: Remove and replace your catalytic converter. Prices of catalytic converters can vary widely and are most expensive in places with strict smog enforcement rules, like California.
What’s making a rattling noise inside my wheel wells?
What will you find inside your wheel wells? This is where your wheels, your tires, your brakes and most of your suspension parts are found. Rattling noises that come from the wheel wells can be narrowed down to a few sources:
The wheels and tires
It doesn’t happen very often, but the bolts or lug nuts that hold your wheels on can work themselves loose. If this happens, you could hear a rattling noise caused by the loosened wheel moving back and forth on the wheel hub. If your car has steel wheels with hub caps covering them, a loose lug nut or bolt can come off and get trapped inside the hub cap, making a rattling noise as the wheel turns.
The fix: This is serious! You should pull over and stop your car immediately. Set your parking brake. Now get out and check whether your wheels are securely attached to the vehicle. Grab each tire with your hands at the 10 o’clock and 2 o’clock positions. Rock the tire in and out to check if it is loose. If you feel any motion, get out your lug wrench and tighten all the nuts on that wheel. If this situation has been going on for long enough, the threads on the lugs may be damaged and can’t be tightened. Your brakes may also be damaged. In this case, it is best to have the vehicle towed to your mechanic. Once there, the lugs, and any other items affected, should be replaced as needed. If there is extensive damage to be fixed, this can get expensive.
The parts in your suspension
The suspension system in your vehicle is made up of springs, shock absorbers or struts, sway bars, and links that are connected to each other. The steering is also built into the front suspension. When all of these parts are operating properly, you get a comfortable ride and good cornering. As they wear and age, you may hear rattling noises coming from the wheel wells. These noises can be caused by:
- Suspension components that are damaged or bent
- Sway bar links that are loose
- Shock absorbers or suspension struts that are worn out
- Bushings that are loose or worn
The fix: A mechanic should thoroughly inspect your suspension. You probably won’t be able to diagnose the problem, unless something has become detached and is obviously hanging loose, or your struts/shocks are leaking oil. It might be something as simple as replacing a bushing or tightening a loose connection. But you would have to replace worn-out shocks or struts, or some other parts that are damaged. Get any suspension or steering noises fixed right away – you don’t want these systems to fail while you are driving! Your repair costs will vary, depending on how bad the damage turns out to be.
The brakes in your car are complex mechanisms. Your brakes are attached to the suspension, next to where the wheels and tires are bolted on. Your brakes move up and down with the suspension’s movement, providing the stopping power to slow down the wheels. Most brakes made today are disc brakes. They use friction pads to press against the rotor, a flat disc that rotates along with each wheel. As the pads press on the rotors, the wheels slow down and stop the vehicle.
Eventually, your pads will wear down and need replacement. If your brake pads are not changed at that point, they will use up all of the friction material. Then you will have metal-to-metal contact, which gives you very poor braking, plus some scraping and rattling noises as you destroy your brake rotors, along with other components of your brake system. At this point, you may be unable to stop your vehicle – and that’s a bad thing!
The fix: Stop driving and get the car to your mechanic immediately. Driving a vehicle with brakes that don’t work is a recipe for disaster! Your mechanic can identify the source of the problem and repair your brakes. New brake pads, rotors, and other parts may be needed, based on the extent of the damage. The more work that needs to be done, the more it will cost.
Is it worth fixing that rattling noise in your car?
There are many different types of rattling noises that can come from many different parts of your car. Some have simple, low-cost fixes. Others can be very costly.
If a cheap fix won’t take care of your car’s rattling noise, and you don’t want to lay out for an expensive repair, you have a decision to make. Here are some questions to ask yourself:
- What will it cost to fix the rattling noise?
- What is your car worth?
- How many miles are on it?
- Does your car have any other chronic issues that could result in a big repair soon?
- Will the brakes or tires need replacement soon?
- Is it time to cut your losses and get rid of your car now?
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