Common issues in timing systems

SKF mechanic at heart2023-01-16

The timing system is a crucial part of the four-stroke internal combustion engine. Its components drive the synchronized rotation of the camshaft(s), ensuring the engine’s inlet and outlet valves open and close at the proper times. This means that if any of the timing components fail, the car will no longer operate properly, which can cause costly damage to the engine.

Let’s look at some of the common issues that can impact the timing system.

Pulley Misalignment

To be sure the timing works as intended, all pulleys must be perfectly aligned to allow the belt or chain to run evenly in one line. The two most common types of misalignment are:

  • Parallel misalignment – When pulleys have been improperly positioned on their shafts, other timing system components, such as belts, can be damaged. 
  • Angular misalignment – This is due to non-parallel, skewed shafts, which can be a result of incorrect belt tension causing a pulley to tilt.
  1. Damage due to parallel pulley misalignment
  2. Damage due to angular pulley misalignment

Incorrect Timing Belt Tension

There are two types of belt tension issues that can impede the performance of the timing system overall:

  • If the belt tension is too low, the belt may jump and cause noise and uneven wear. Low tension may also drastically decrease the belt’s life span. 
  • If the belt tension is too high, the pressure put on the coolant pump bearings and the tensioners becomes excessive, which can cause the coolant pump to fail and the tensioners to break. In extreme cases, the alignment of the pulleys can be distorted and cause further damage to the entire system. 

Inadequate Timing Chain Lubrication

Lubrication, like with most parts of the modern combustion engine, is vitally important for the proper functioning and service life of the timing chain system. Oil is used to lubricate the chain and the tensioner that actuates the chain guide, maintaining tension in the system. Inadequate lubrication can result in:

  • Polluted oil damaging components
  • Excessive movement and wear to components

Damage caused by inadequate chain lubrication

Gear Misalignment

One of the most common installation errors, according to timing chain suppliers, is misalignment. This can be caused by a variety of simple mistakes, including:

  • Installing the cam sprocket backwards
  • Using the wrong thickness of washer under the sprocket
  • Failing to press a cam gear all the way on
  • Applying incorrect torque on sprockets without a key slot