My Car Shakes While Idling

Your car should run smoothly, whether moving or stopped.

If it shakes while it idles, you could be in for a visit to the mechanic.

image of woman steering her car, driving at night.When your car is functioning properly it should run smoothly in all driving modes – moving fast, slowly, stopped and idling. A sign that the engine needs to be checked, and possibly need some repairs, is when your car shakes as it idles. An AAMCO Colorado mechanic can run a multi-point inspection and diagnostics to identify the issue and recommend the right repairs.

Here are some reasons why your car shakes or shudders while it idles, and what repairs you might need.

Dirty or Worn Out Spark Plugs Are the Most Common Cause of Engine Shaking

Spark plugs that are dirty or worn out will not fire properly, which means they aren’t igniting the fuel in each of the piston cylinders in a timely manner. This causes the engine to misfire, which is commonly known as “not firing on all cylinders.” Dirty spark plugs can sometimes be cleaned, but should just be replaced as they are generally inexpensive. A good mechanic can ensure they are installed and calibrated correctly.

A Dirty or Faulty Fuel Intake System Can Cause Engine Shuddering

An improperly adjusted or dirty fuel intake system can easily cause the engine to shudder and shake. As a car ages and accumulates thousands of miles of wear and tear, its fuel intake valves can become clogged with sludgy buildup. Clogged or poorly adjusted valves deliver uneven amounts of fuel to the engine; and without an even, continuous supply of clean fuel, your engine can start to shake or shudder while it idles. Along with the intake system, the fuel pump should be checked for wear and possible issues.

Loose, Disconnected or Broken Hoses Are a Common Culprit of Engine Shaking

Hoses are a culprit for many engine performance issues, and excessive vibration and shaking is no exception. All cars have vacuum hoses, which are connected to various points in your engine. They serve to clear and expel the by-product gases, such as exhaust and fumes, from the engine. A leaky or broken vacuum hose can cause major shaking in the engine. If the hose is loose, disconnected, or worn out, multiple engine problems can occur. The engine, might misfire, lose power, chug or stall, or even shut down entirely. One of the symptoms of a vacuum hose leak is violent shaking or shuddering of the engine. Luckily, these issues can be readily identified and fixed by a good mechanic.

Worn Out or Misadjusted Timing Belt and Other Belts Can Cause Noises and Vibration

image of car engine hood open.Your car’s timing belt, serpentine belt, or v-belts on other systems, are common causes of engine vibration and squealing. A loose timing belt or other belts that might be loose or worn out will cause things like fans and other parts to not rotate or operate properly or at the correct speeds. This will result in strange noises and vibrations from the engine. Luckily these problems are easily addressed by having the belts inspected to make sure they’re installed, adjusted and operating properly.

Broken Motor Mounts Can Cause Severe Engine Shaking and Should Be Fixed

Motor mounts keep the engine attached to the car. If the vehicle shakes or the engine shudders a lot when stopped at a stoplight, or when parked with the engine idling, it might indicate the motor mounts or transmission mounts are damaged or broken. To see if this is really the problem, shift the car into neutral. If the shaking decreases, it’s a strong indicator the engine’s motor mounts need to be inspected by a mechanic.

AAMCO Colorado Can Diagnose Engine Shaking

image of mechanic running diagnostics on engine, hood up.Given the range of potential symptoms and causes of your car’s engine shaking, from bad spark plugs to broken motor mounts, it’s important to have a mechanic do a thorough inspection as soon as possible. Visit an AAMCO Colorado transmission repair and total car care center near you. When issues arise and you need diagnostics, brakes, suspension or shocks, or engine repairs – including belts, hoses, radiators, and air conditioning repairsschedule an appointment for a system diagnostic test before it’s too late.

If you have questions about your car’s road readiness, or about car repair and maintenance topics, AAMCO Colorado can help. You can also go online and use the AAMCO Colorado Ask a Mechanic feature to submit your auto repair questions. They will be answered by a real AAMCO Colorado mechanic as soon as possible.

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