Drive belts — replacement and tensioning (Mercedes-Benz S-Class W126)

Before installing new belts, the tensioners or units that tension the belts must be set to their original position. New belts are subject to strong initial stretching. In order to prevent noise and premature wear of the belts due to slippage, new belts should be tightened after a test drive, or after checking the operation, or after the engine has been running at medium speed for 10 minutes.

The belt is tensioned correctly if the specified deflection value is not exceeded. The deflection value is checked under a vertical load of approximately 60 N (6 kg) at the midpoint of the greatest deflection and should be approximately 10 mm under these conditions. The deflection of the power steering pump belt should reach approximately 5 mm. Using a special measuring device, the following values are obtained:

• The new belt with a section width of 9.5 mm is tensioned by 30 units.
• With a width of 12.5 mm - 50.
• Belt with a "mileage" of 20-25 units or 40-45.

Belt drives for 6-cylinder engines

Belt drives for 8-cylinder engines

Article was obtained from the portal MERCEDESMAN