The warning light usually looks like a rectangle or the top of a 9 volt battery, with a minus sign on the left and a plus sign on the right. This warning light may also indicate a failing alternator or a battery that is no longer holding a charge.
Your first sign of a loose serpentine belt may actually be the vehicle overheating if it fails to spin the water pump pulley. If at all possible, avoid allowing the vehicle to overheat, as it can cause permanent and expensive damage to the cylinder head.
A squeal that begins only when you start the car cold may be a strong sign of a loose belt. A squeal the coincides with the car’s acceleration is also likely due to a loose belt.
A lack of cold air from the air conditioning and and increase in tension in the steering wheel are both signs of these accessories failing. Be sure to check the power steering fluid if you begin to have issues with your power steering.
You will need to remove the belt to replace the damaged accessories or pulleys if one fails. Ensure you put the new belt on with the correct tension, otherwise more accessories may fail.
Removing the keys from the ignition is a safety precaution that could prevent you from getting hurt or damaging the vehicle. You may also want to disconnect the negative terminal of the battery. Serpentine belts move at high rates of speed and can catch any loose fitting clothing or jewelry if you get close while the engine is running.
The belt should have about a half an inch of play when at the appropriate tightness. If there is less than a half an inch, the belt will need to be loosened, if there is more, it will need to be tightened. Leaving the ruler over where the belt was as you press on it can help make the amount of flex in the belt more apparent by showing how far it’s flexing from the ruler.
The inside of the belt is the side with grooved edges. If the belt is cracked, it will need to be replaced.
If the edges of your serpentine belt are shiny, the belt is too loose and needs to be tightened. If the belt is showing sign of wear like polished edges, it likely will need to be replaced. A frayed belt edge, however, means the belt is misaligned.
If the grooves of the belt have glazed over, you’ll need to replace the belt. Glazing may occur in conjunction with cracking as described in the step above.
You may still want to check the tension of a damaged belt if you need to drive the vehicle to get repaired. It is not recommended that you operate a vehicle with a damaged, loose, or severely worn serpentine belt.
If you do not have the owner’s manual for your vehicle, you may be able to find the specifications on the manufacturer’s website.
Some tension gauges work my pushing on the belt, while others work by pulling on it. Your specific tension gauge will provide instructions as to how best to use it to get the best reading.
If your specific gauge instructs you to do otherwise, disregard this step. Slow steady pressure (when pushing or pulling) is the best way to get an accurate reading from your gauge.
Some vehicles have an auto-tensioner pulley. If your vehicle has one and the belt is too loose, the pulley itself may need to be replaced. Other vehicles may allow you to adjust the tension on the belt by loosening the alternator bolts and adjusting its positioning.
