Several weeks ago, the alternator went out in my 1998 Dodge Caravan. With the help of my neighbor, in a few hours, we had a new one installed, along with a fresh serpentine belt. Within a couple of weeks, the engine developed a "chirping" sound originating from the front, or belt side of the engine. After Googling "chirping belt", I determined with 95% certainty it was the belt tensioner. A belt tensioner is a device that keeps tension on the serpentine belt to prevent it from slipping. This part is used extensively on front wheel drive vehicles and on engines which use one belt. It has a heavy duty torsion spring in a cast aluminum housing which provides the tension on a lever with a pulley mounted to it. Either the spring or the pulley bearing can cause the failure; in this case the bearing failed, which made the "chirping" sound. The van has about 97k miles on it; the tensioner was replaced at 47k miles. Further searches recommended replacing the tensioner every time the belt is replaced. This certainly held true in my case. A few more searches on Google gave a detailed procedure to do the job. Local auto parts stores had the part for around $45.00.

Things You Will Need

Tools needed for this job:

3/8 drive ratchet

15mm universal socket

15mm open end wrench

15mm 3/8 drive socket

18" to 24" 3/8 drive extension

long screwdriver


12" pipe (to fit on the ratchet handle for more leverage)

bungee cord or rope

trouble light

jack stands (or cinder blocks)

Step 1

Pull the vehicle into the work area and let the engine cool down. This may take some time. Do not work on a hot engine; you will get burned. Jack up the vehicle high enough to allow crawling under it. Use jack stands or cinder blocks to support the vehicle. Do not work on a vehicle supported only by a jack.

Step 2

Open the hood and locate the belt tensioner on the left side of the engine. Using the 15mm open end wrench on the belt tensioner pulley nut, pull the wrench towards the front of the vehicle to relieve the tension on the belt. If the spring didn't fail, it will require quite a bit of force; be careful! Don't let it slip. Use a short length of pipe over the end of the wrench for extra leverage if necessary. Once the tension is relieved, tie the wrench off with the rope or bungee cord to keep it in tension.

Step 3

Locate the alternator which is at the top of the engine inline with the belt tensioner. Using a 15mm socket and ratchet, remove the positioning bolt at the top of the alternator; this bolt clamps the alternator in position. At the bottom of the alternator is another 15mm bolt. Loosen this bolt and pivot the alternator towards you. This will provide extra slack in the belt, allowing removal of the belt around the alternator pulley. Once the belt is off the alternator pulley, carefully release the wrench holding the belt tensioner in tension. Now you are ready to remove the belt tensioner.

Step 4

Position the trouble light over the tensioner. Crawl under the vehicle with the 3/8 drive ratchet, 24" extension and 15mm universal joint set-up. You will be able to thread the extension through a space between the frame and the steering rack; up to the single 15mm bolt holding the tensioner in place. It will be stubborn; you may need a short length of pipe for extra leverage. Remove the bolt. Slide out from underneath the vehicle.

Step 5

From the top side of the vehicle, position the long screwdriver between the tensioner housing and its mounting bracket; tap the end of the screwdriver with the hammer. This will jar the tensioner loose. You can now remove the tensioner.

Step 6

Position the new tensioner in its approximate location. You will need a helper to hold the new tensioner in place. Crawl back under the vehicle with the ratchet, extension, 15mm universal joint setup and the tensioner bolt. Place the bolt in the universal socket and thread it up to the tensioner bracket. Gently thread in the bolt by hand making sure it starts and then tighten securely. Use the short length of pipe for extra leverage. Slip the belt back on to all the pulleys which will require working from over and under the vehicle; there is a diagram of the belt routing on the suspension strut housing. Make sure the belt is routed properly.

Step 7

Relieve the tension of the tensioner using the procedure in Step 2; position the belt over the alternator pulley and pivot the alternator back to its original position. Install the 15mm bolt to secure the alternator in this position. Tighten the alternator pivot bolt. Release the tension of the belt tensioner. Clear all tools and lights from the engine area; start the engine. It should run smoothly and "chirp" free.

Even though there seems to be a lot of steps in this procedure, it goes very quickly. The whole job took about an hour, including jacking and blocking. If you have reasonable mechanical skills and the proper tools, doing this job yourself will save you the going labor rate and parts mark-up every shop charges. It is a winner for backyard mechanics!

Tips & Warnings