While you’re sitting at the stop sign or light waiting to drive, your car is idling. It’s pretty common for your car to vibrate a little while you’re just sitting there and not accelerating. The rotating crankshaft, transmission gears, and other inner workings of the car can cause vibrations that you will be able to feel. However, in some cases, the vibration from the engine can be higher than normal and cause a rattling noise from the engine compartment.
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Typically, the engine vibrations will be this strong when there is something wrong with one of the parts of the engine. A faulty or damaged part will cause the process to work incorrectly, which will result in the shaking and rattling noise. Identifying which one of these parts is causing the vibration lets you realize the issue and point it out when you take your vehicle to a mechanic. We have listed the top reasons behind a higher-than-normal engine vibration and car shaking while idle.
Reasons Your Car Is Shaking At Idle And Making Engine Noises
There could be a host of reasons that you are shaking at idle, but there are a few main causes that are typically behind the shaking and noises coming from the engine compartment. This problem is one you should not ignore.
- Worn out Or Damaged Spark Plugs
A worn-out spark plug is the main reason why your car engine will vibrate or shake at a high rate. A spark plug is used to deliver an electrical current from the ignition system to the combustion chamber of an engine to ignite the compressed fuel and air mixture via an electric spark. The spark plug must ignite the fuel and air while still containing the combustion pressure to remain within a normal limit in the engine.
The spark plug has two primary functions. The first function is to ignite the air and fuel mixture. The electrical energy is moved through the spark plug, skipping the gap in the plugs firing end if the voltage to the plug is at a high enough level. The electrical spark will ignite the fuel and air mixture within the chamber.
Spark plugs are in charge of removing heat. The temperature of the end of the plug’s firing portion must be kept at a low enough temperature to prevent ignition prematurely. However, it must remain high enough to get rid of unwanted thermal energy from the combustion chamber.
If the spark plug can’t complete these important aforementioned jobs, then it is a worn out or damaged plug. This can prevent the fuel and air mixture from being properly ignited within the cylinder compartment. Without igniting the fuel and air, the cylinders will misfire. The misfiring of the cylinders will result in the car shaking and vibrating, since the cylinders will misfire during idling. Buying new spark plugs is the best solution for resolving this issue.
Fortunately, spark plugs are incredibly inexpensive for such an important part. The spark plugs usually cost less than $10 a piece, which won’t add up to be that much money even if you need to replace multiple plugs at once. The typical amount you would pay for a spark plug replacement is between $16-$100, and the labor will be around $40-$150. Replacing the spark plugs is crucial in order to prevent your car from shaking while idling or shaking at slow speeds.
- Improper Timing Belt
The timing belt in your car ensures that many of the critical components are functioning at the right levels. The timing belt, also known as the timing chain, is part of the internal combustion engine. It synchronizes the rotation of the crankshaft and camshaft so that they work together to open and close the engine’s valves at the correct times. The engine must open and close during the cylinder’s intake and the exhaust strokes. The stroke happens when the piston moves from top to bottom and vise versa.
The timing belt needs to keep synchronization between the crankshaft and camshaft to ensure the engine runs. If the timing belt fails, your car will shut down, which can create a dangerous situation. You need to change your timing belt on a regular basis, to prevent the belt snapping. If the belt snaps, the engine damage could be extensive and cost you an extreme amount of money.
- Loose or Disconnected Hoses
An additional reason that your car engine is vibrating and the car is shaking can be due to a loose or disconnected hose that should be connected to the engine. The hoses in your car are important parts to the engine’s cooling charging, and air conditioning mechanisms.
Hoses are made of flexible rubber that are designed to absorb the vibrations you will run into while driving. The hoses are connected to the radiator, heater, fuel lines, vacuum lines, air conditioning, and steering. Some portions of the hoses are also connected to the engine in order to absorb the shaking and vibrations from the car. These hoses can wear down from the inside, and still appear stable on the outside. This makes it hard to detect a faulty hose, and can make the detection of a repair difficult.
The dryness on the rubber of the hose can cause an engine hose to break down over time. You should replace your hoses at around 50,000 miles, although it should be checked more frequently for any abrasions or breaks. The hoses are after all the cooling system’s weakest component, and can cause your car to shake while idling if not careful.
Since the hoses are the engine system’s weakest structural component, they need to be checked and repaired more frequently than other parts. The hoses are also subjected to varying degrees of heat, cold, dirt, oils, and other debris that may come through the passageways, meaning they undergo quite a bit of wear over time.
There is some easy maintenance you can perform to ensure that your hoses are working correctly to prevent your car from shaking while idling. Be sure to check the coolant-recovery tank often to maintain the proper fluid levels. You may need to replace one of the coolant hoses if your coolant isn’t working correctly. If the tank continues to be low after you refill the tank to the correct level, then you are correct in suspecting a leak.
When the engine is cooled off, squeeze the hoses with your thumb to feel for soft spots. A good hose won’t have any soft spots, and will have a firm feel between your hands. Turn the hose over and look for any cracks and bulges along the line. Look for parallel cracks around the bends due to ozone damage, hardened glassy surface due to heat damage, or abrasive damage as a result of rubbing.
After you have inspected the hose, flush the coolant by following the instructions in the owner’s manual. If you have a clean coolant, there is less of a chance that problems will occur within the lines. Following these simple maintenance steps can ensure that your hoses have a long lifespan and won’t cause your car to shake while idling.
- Improper Fuel Intake Adjustments
If the fuel intake system isn’t adjusted and calibrated correctly, it can cause the engine to vibrate at a high level, causing your car to shake while driving at low speeds. The fuel intake system can also cause your engine to shake while idling, due to the engine not getting the right ratio and amount of fuel and air mixture. By adjusting the idling speed on the carburetor and cleaning the fuel intake system, you can solve this problem.
The carburetor is a device that mixes the air and fuel for the proper air to fuel ratio in order to use for combustion. By changing the speed on this device and cleaning the fuel injection system for transporting the fuel, you can ensure that your car won’t shake anymore.
- Damaged Motor Mounts
If your motor mount is damaged, this can cause the engine to vibrate and your car to shake while idling, or even while the car is stopped. Since it is more uncommon for your car to shake while stopped, if you feel your car shaking, a damaged motor mount is usually the culprit. This component is in charge of supporting the engine within the compartment, and absorbing the engine vibrations. If the motor mounts aren’t working properly, the vibrations will be much higher.
Motor mounts work by having one end of the system attaching to the engine, and the other attaching to the vehicle frame, thereby holding the engine in place. In addition to holding the engine securely, they also isolate the steel from the engine vibrations and the shaking occurring in the vehicle. The motor mounts slow down the vibrations and processes happening around the engine to allow for movement.
When assessing the wear that has occurred on the motor mounts, you need to take some time to go over the mounts and see where and if any damage has occurred. Common reasons that the motor mounts can deteriorate is due to time and constant stop and starting. Extended use and thousands of stops can result in the rubber holding the metal of the mounts together breaking down. The rubber can crack, or become loose and unusable. Liquids can leak onto the mount itself, and will accelerate the breakdown process.
Another reason that the motor mounts might breakdown is due to some changes within the engine power paired with reckless driving. This combination can cause the power to overcome the original design of the motor mount, and cause torque-induced motor mount failure.if there is extended shaking and loud noises coming from under the hood while you try to accelerate, then it is typically time to replace the motor mounts.
Larger engines will require a jack or a prop to be able to check under the hood and evaluate the damage. If you discover a broken mount, the likelihood of the other mounts being stressed out and overworked is much higher.
Why Is My Check Engine Light On While My Car Is Shaking?
Your check engine light might come while your car is shaking for a host of reasons. The first reason that it might be on is due to the oxygen sensor providing a trouble code. These sensors are designed to measure the ratio of unburned oxygen to fuel, in order to see if the ratio is providing an optimal working capacity.
If the oxygen sensors are malfunctioning and sending data that doesn't make sense, your fuel efficiency can be reduced – sometimes by up to a whopping 40%. Your car will often time stall, hesitate while trying to accelerate, or have a rough and shaky idle.
Oxygen sensors typically fail due to an accumulation of residue. This occurs because of oil leaks in the engine, a fuel mixture that is incorrectly balanced, or coolants have left behind deposits that interfere with the sensor accuracy. You will need to replace your oxygen sensor to turn the check engine light off and prevent your car from having a rough idle.
It Could Be Due To Malfunctioning Vacuum Hoses
The second reason that a check engine light could come on while your car is shaking is due to the vacuum hoses malfunctioning. A broken or damaged vacuum hose can trigger an error code in the emissions control system, which can result in the failure to pass inspection. They also are a huge part of the fuel injection system.
If the vacuum hose has a leak, the vehicle’s computer can’t control the flow and pressure of the fuel, causing the engine performance to deteriorate. The symptoms of this deterioration of the engine include a rough idle, causing the car to shake.
The leaky vacuum hose has various causes, like the hoses wearing out over time, becoming brittle due to time, and a plastic connector or gasket failing. You need to repair the vacuum hose by locating the leak, which is typically heard by a hissing sound. You can find the leaking hose by moving the hoses individually while letting your car idle. This allows you to see which hose is causing your car to shake and keep the check engine light on.
What Do I Do If My Car Is Shaking And Requires An Expensive Fix?
If your car is shaking while driving at low speeds or while idling, you need to determine the cause of the shaking first and foremost. If you don’t have the tools required to diagnose the fix, or the funds to take your vehicle to a mechanic, you should look into other options. The best option for you is to bring your car to a reputable location that can give you money for your junk car, so you can start saving for your next vehicle. Stop by CashCarsBuyer to receive a fair quote and some easy money.