How to Find and Repair Engine Vibrations

 Modern engines have many moving parts both internally and externally. Vibrations can occur at different times in the operation of the engine such as when the engine is at high or low RPM, or if the engine is hot or cold. Some vibrations are constant and are present throughout the RPM range. These vibrations can be caused by something mechanical, ignition or fuel related.

How much will it cost?

 Depending on the cause of the vibration the cost can vary wildly. If the belt tensioner is out the cost will be relatively mild, about $70.00 US for the part and about the same to install it in most cases. If you have a more serious issue such as the balance shaft system is non-operational due to a mechanical failure the engine may need to be removed and repaired which can cost anywhere from $1200.00 to $2200.00 US depending on how many parts need to be replaced.

Most popular vibration causes

  • When an engine misfire occurs it will cause a vibration which can happen at particular time in the engines operation and maybe consistent or not depending on the type of misfire. The vibration is generated because all engines are symmetrical, and when part of the circle is missing the engine becomes off balanced. This can trigger a "Check Engine Light" in most cases which can help detect the particular cylinder having trouble. Learn More - Engine Misfire

  • Most four and six cylinder engines are equipped with a balance shaft mechanism which consists of two counter weighted shafts driven by the crankshaft. These shafts vibrate inside the engine to offset balance and vibration issues which are the natural characteristics of the engine's design. If the balance shafts are non-operational due to mechanical failure or wear the engine will vibrate. These shafts can also be driven from the engine's balance shaft chains independent of the camshaft timing chain. Here is an image of the balance shafts which can cause a rattling noise when bad.

Balance Shafts

  • A serpentine belt tensioner is designed to keep the belt tight during the engine operation and also take up the slack as the belt naturally wears. This spring loaded pivot based part can wear allowing the belt to "bounce" as it loses and gains traction among the drive and accessory pulleys. This can be seen by observing the tensioner while the engine is running which should be relatively smooth. If you notice a vibration the part is warn and needs to be replaced. Learn More - Serpentine Belt Tensioner Replacement

  • Engine mounts are a vulcanized rubber mount that the engine and transmission sit upon to shield the car frame and body from the natural operational vibrations of the engine. When these mounts fail due to damage or natural wear they lose their dampening ability. The best way to inspect an engine mount is from under the car using a flashlight to check the integrity of the mount. The failure will be obvious as the rubber part will be blown out, torn or missing which warrants replacement to fix the problem. Learn More - Replace Engine Mounts

  • If the vibration begins when the heater or air conditioner is switched on this can be caused by the system being over charged. Due to the above normal high side pressures the compressor is forced to overwork itself creating a vibration. This is an easy fix simply bleed off some of the refrigerant to obtain normal pressure levels. Learn More - Air Condition Pressure Levels

How serious is it?

 When an engine vibration is present excessive wear of internal or external parts is occurring. The first thing you should try is to remove the serpentine belt and then start the engine. If the vibration goes away then the problem is one of the accessories or the belt tensioner. If the vibration is still there, the problem will be internal. If the engine is not misfiring suspect the balance shaft system. To find out if you engine has a balance shaft or not please ask one of our online mechanics, it's free.

Article published