Mechanics

Vibration

Repairing Vibrating Sounds

Vibrations are annoying and can be difficult to detect the origin of the generation point. Vibration sounds are different from other related noises because vibration noises can travel a distance from the actual cause, for example: If an engine mount has failed allowing the engine to contact the car frame it can sound like the vibration noise is being created near the middle or rear of the car. Or if the rear tires have devolved a cupping condition it can sound like the vibration noise is being generated from the whole car. This transference of vibration noise is called telescoping. If it is not clear where the vibration noise is being generated from it helps to turn your head from side to side while taking note on which ear is hearing noise. This technique is helpful when troubleshooting the origin of the noise. 

Vibration noises can be generated by almost any part of the car because most components are subject to rotating parts. If your car is vibrating because the engine is misfiring please visit why is my engine misfiring? We have list common; engine running with car not moving and car in motion problems below:

Engine Running, Car Not Moving: This section includes symptoms that present themselves when the engine is running only.

Check Engine Mounts - Engine mounts are used to minimize engine vibration by isolating the engine from the car frame. These mounts are constructed by using rubber vulcanized between to metal plates with threaded studs that bolt to the engine and the frame of the car. When motor mounts become worn they allow the engine the contact the frame causing a noticeable vibration. Inspect the engine mounts for integrity, look for any oil, cracks or separation of the mount. Remove the failed engine mount and replace if needed.

New Engine Mount
New Engine Mount (appearance will vary)

Vibration Noise When Air Conditioner is On - The air conditioner is designed to operate using a electromagnetic clutch assembly that receives a command signal from the activation switch. This command controls when electricity is supplied to the compressor clutch that engages and disengages the air conditioner system. If the air conditioner expansion valve/office tube is plugged or the system has excessive oil or refrigerant it can cause the system to vibrated when activated. To check for this condition the system will need to be drained and refilled to proper specifications.

Inspect Harmonic Balancer - The harmonic balancer on your engine is used to help silence engine vibration by utilizing a rubber mounting metal ring attached to a hub that is connected to the front of the engine. If this ring becomes dislodged because the rubber insulator has failed it will allow the outer ring to bounce on the rotating hub. This condition will produce a vibration noise that will change with engine speed. To check for this condition remove the multi rib belt and check the harmonic balancer condition. If the outer ring is lose replacement is required.

Failed Harmonic Balancer
Failed Harmonic Balancer

Checking Flex plate Balance Weight (automatic transmissions only): The flex plate on the rear of your engine is designed for three reasons, first it connects the engine to the torque converter of the transmission, next it allows the starter to engage and crank the engine over and finally it contains balance weights that help the engine stay in balance when operating. These counter balance weights are spot welded onto the flex plate. If these weights become dislodged it will cause the engine to vibrate. To check for this condition remove the flywheel cover. Using a flashlight inspect the weight location, also there could be signs were the weight was thrown off of the flex plate while the engine was running. (Note: not all cars have a weighted flex plate)

Weighted Flex Plate
Weighted Flex Plate

AUTHOR


Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)