Mechanics

Abnormal Engine Noises

Step by step troubleshooting instructions on how to fix abnormal engine noises. This article pertains to all non electric vehicles.

Difficulty Scale: 4 of 10

Tools and Supplies Needed

  • Flashlight
  • Small mirror
  • Protective eyewear and gloves
  • Wrench and socket set
  • Hydraulic jack w/stands
Some engine noises are normal for example: some Chevy and Ford engines have short skirt pistons or all roller valve train, a minimal amount of engine ticking noise is normal. Fuel injectors also make a slight clicking noise when the engine is idling. These noises are normal and no repair is required, but if unexplained noises exist, the following steps are the most common causes.

Step 1 - Check the engine oil level, an engine depends on clean oil to lubricate the internal moving parts, if the oil level is low or dirty it can cause internal engine parts to malfunction. For example: a valve lifter is responsible for holding valve train clearance to a minimum, if the oil level is low or dirty it can cause the lifter to fail which will allow excess valve train clearance creating engine tapping or clicking noise. In extreme cases it can cause one of the many bearing surfaces to fail causing permanent engine damage. An engine making a slight noise, changing the engine oil and filter with the manufacturers recommended weight (viscosity) oil sometimes helps. Visit - Engine oil change

Step 2 - A squeaking noise could be generated by the engine accessories, accessory mounts, serpentine belt or drive pulleys. When an accessory, accessory bracket, belt or drive pulley fails it can make a rattling, squeaking or tapping noise. These sounds are centrally located near the front of the engine. With the engine off, check the tension of the belt/belts, it should be at medium tension a loose or worn belt can make a loud squealing or chirping noise, check the belt tensioner and the size of the belt to make sure the right belt is installed. To isolate the origin of the noise, remove the serpentine belt and start the engine. Visit - Serpentine belt removal

If the sounds disappears an accessory, accessory bracket, belt or pulley has failed. With a flashlight inspect the brackets and pulleys that connect the alternator, air conditioner compressor, power steering pump, and air pump if equipped. Look for signs of rust (reddish pounder), this indicates a broken or loose metal part rubbing together, which can generate squeaks and ticking noises. If the brackets look okay rotate each accessory pulley by hand and check for hard spots or a seized bearing.

Step 3 - If a tapping or ticking noise from the upper half of the engine remove the valve covers. Each valve utilizes a spring that returns it to its original position, closed. If a valve spring has broken or a cam lobe is worn down it will cause the engine to create a tapping or clicking sound due to the excess clearance. To test for this condition, remove the ignition coil connector, ignition system or fuel pump fuse to disable power to the ignition or fuel system. Have a helper crank the engine over while watching the rocker arms or cam lobes, making sure all valves are traveling the same amount. If one or more lobes are traveling less than the others the engine has a flattened cam lob and the camshaft needs to be replaced, or the hydraulic lifter/follower (where applicable) has collapsed and will need to be replaced. Also inspect the condition of the valve springs, using a flashlight and a small mirror to aid in the inspection to look for broken springs. If a broken valve spring is discovered replacement is required to correct the problem. When checking valve springs look at the height of the valve springs and retainers in the closed position, they should be exactly the same height. If one valve is higher or lower something is wrong with the cylinder head the valve or valve seat and needs to be repaired.


Replacing a Camshaft

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 2013-12-20)