I own a 2007 Subaru Forester. I swapped both belts on the car however it still squeaks when i decelerate. Before the belts were swapped it would squeak only when I accelerate and decelerate. No issues when maintaining speed. Any ideas?

  • Also bearings seem to be okay when spinning them
    – Albert
    Jul 1 '19 at 0:48
  • 1
    Are you sure they are tensioned correctly? Have you checked - there are tools to check tension - pushing with a finger is not sufficient.
    – Solar Mike
    Jul 1 '19 at 4:54
  • They should be tightened correctly. My other sibling has the same year and make. There does not squeak.
    – Albert
    Jul 2 '19 at 2:04
  • All belts and pullys are not created equal. Add a small amount of tension on both belts and see if the situation changes. Also, are there any oil leaks around the plastic "timing cover" areas? Belts do not like any lubrication. Try spraying the belts and pullys with clean water from a spray bottle to see if that will induce squeaking. If it does, you have either a tension problem, or the pullys/belts are not clean and are slipping.
    – SteveRacer
    Jul 2 '19 at 2:25
  • I know last fall when this started to happen my oil pressure sensors started to go and spray oil all over the place. Not to mention there is a small hole in the timing box
    – Albert
    Jul 3 '19 at 11:27

Perform the tests listed in this post to determine whether you have a tensioner, alignment or a worn belt issue

http://ricksfreeautorepairadvice.com/fix-serpentine-belt-noise/ which says:

How to test for serpentine belt noise

Perform the test under the same conditions as when you hear the noise. For example, if you hear a squeal first thing in the morning on a cold engine, test it under those conditions. Since you’ll be leaning in close on a running engine, be safe and remove loose clothing and jewelry. And use a powerful flashlight to see where you’re shooting the water. Have a friend help you, especially if the noise only occurs at higher RPMS. And you really want a second person there to shut off the engine if you stick your hands where the don’t belong.

Most belt chirps and belt squeals occur in the shortest spans between two driven components. So start the engine and spray a stream of water onto the ribbed side of the belt before it wraps around a pulley.

If the noise goes away, but returns again in a few minutes, the problem is misalignment.

If the noise gets louder, the problem is too little belt tension.

To diagnose misalignment, start by using an automotive stethoscope probe. Click here to read how to do that.

If you suspect a tension issue, click here to read about testing belt tensioners.

You may need a long wrench to move the serpentine belt tensioner.

  • Hello! Could you summarize that info to prevent link rot? Thanks!
    – Cullub
    Aug 1 '19 at 20:18
  • Not my answer, but the link is still good. I went ahead and amended the answer. Jul 26 '20 at 21:58

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