How To Tighten the Serpentine Belt on a Mercedes Benz 190E

A serpentine belt is a multi-rib single continuous belt that allows several peripheral components of a vehicle’s engine such as the alternator, the car’s air conditioning compressor, the water and air pumps or the power steering pump to run. The serpentine belt is installed to transfer the energy from the vehicle’s engine to the components. Mercedes Benz first installed the serpentine belt in their 190 car model series in 1985. Regular wear and tear and age of the serpentine belt can cause it to loosen. Below are the steps on how to tighten the serpentine belt on a Mercedes Benz190E.

  • Open the hood of your car and visually inspect the serpentine belt. There may be four to six pulleys installed in your car model.
  • Grab two opposite portions of the serpentine belt between two pulleys with your hand. There should be enough tension there. If you can bring the two sections of the serpentine belt close together that means that the belt is quite loose.
  • The serpentine belt is normally self-tensioning but there are some that has a tension adjustment screw that can be loosened or tightened to maintain the proper tension of the serpentine belt.
  • Inspect all the pulleys and how the serpentine belt is threaded around each one. The belt may have slipped from a groove of a pulley causing it to slacken. The alternator mount may be cracked and needs to be replaced. You may also see some cracks along the serpentine belt that causes it to stretch and lose its grip.
  • Get your Mercedes Benz 190E manual or look under the hood for the diagram on how the serpentine belt is mounted on all the pulleys. You can also take pictures or make a drawing of how it is installed so that you can replace a worn serpentine belt properly.
  • The belt tensioner is smaller than the other pulleys but larger than the one for the alternator. It can either be in the center, between the crankshaft and the coolant pump pulleys or to the side. Give the bolt in front of the tensioner one-fourth or one-half turn and then turn the tensioning nut to the left. This will cause the belt to loosen and you will be able to remove it. Check the whole belt to see if there are cracks and frays that may be the reason why it has become loose. Clean exposed parts to remove dirt and grime that may also contribute to the uneven tension.
  • With the serpentine belt removed you can turn most of the pulleys by hand. Turn each one to see if there turn smoothly with no creaking and without too much resistance.
  • Turn the tension marking pointer until it aligns with the mark on the plate. If the belt is still in very good condition put it back or replace it with a new one beginning from the tensioning pulley then following the diagram. Turn the tensioning nut until the tensioning pointer is aligned with the tension marker and tighten the bolt again. Check that the serpentine belt seats are in the pulley grooves properly.

It is very important that you regularly check the tension of the serpentine belt. If your car squeals when you start it in the morning, chances are your serpentine belt is loose. The squeal will usually stop when the engine becomes hot. Remember that when the serpentine belt is loose, your car engine will stop and you will only be able to restart your car when you have tightened the serpentine belt and/or replace it. Proper and constant maintenance will ensure that your Mercedes Benz 190E is in top running condition at all times.


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