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Piston slap or timing belt tensioner?

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OFFLINE   yosoycharly

  • Member
  • 3 posts
  • Joined 30-July 17
  • LocationBrunswick
  • Vehicle:2000 Subaru Outback
I joined the forum to find someone who could give me a second opinion. My 2000 Subaru Outback (136000 miles) recently developed a tapping noise - mechanic says it's piston slap and has recommended I replace the motor with a used one- for $1700. I've been researching this noise and think it might actually be a bad timing belt tensioner. So - two questions - how bad is piston slap? Can anyone recommend me a good place for a second opinion? I've attached a video of what it sounds like. The tapping does not go away completely when the car warms up. It doesn't get louder when the car warms up. It's not consistent. I'd really like to get another couple years out of the car (should be easy as I work from home and won't put more than 10k a year on the car)




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  • Joined 18-October 08
  • Real Name:Chris
  • Vehicle:My car has 3 pedals, 2 levers, a wheel, and a stick that I control with my 4 limbs to make it go.
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If the sound doesn't go away when the engine is warm, it's not piston slap, but it could be rod knock. And yes, you're correct, a failing timing belt tensioner can cause a similar noise. I've had it happen on one of my cars. 

Do you know the history of the timing belt replacement on this car? If it's never been done, you're WAY past due in the first place. To check the tensioner you're gonna have to remove the timing covers and see if it's loose. It's not a big deal, remove the belts for the alternator/power steering and AC. Remove the crank pulley (22mm socket), and pull all the timing cover bolts out (10mm socket).

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