Skip to content
View in the app

A better way to browse. Learn more.

Ultimate Subaru Message Board

A full-screen app on your home screen with push notifications, badges and more.

To install this app on iOS and iPadOS
  1. Tap the Share icon in Safari
  2. Scroll the menu and tap Add to Home Screen.
  3. Tap Add in the top-right corner.
To install this app on Android
  1. Tap the 3-dot menu (⋮) in the top-right corner of the browser.
  2. Tap Add to Home screen or Install app.
  3. Confirm by tapping Install.

Odd Piston Slap Sound

Featured Replies

that's no piston slap. that sounds bottom end... sorry to say it. sounds like a rod bearing.

damn that sucks ya definitely. Even possibly a idler/ tensioner can cause that. Expierienced that on a forester 2.5 guy claimed bottom end found the timing belt tensioner was flapping around.

Did you do timing belt work to this engine? (too lazy to look up your other thread)

 

Check your crankshaft pulley, it may have a case of "the wobbles", from the bolt not being tight enough.

  • Author

Sorry for the lack of further information.

 

The sound is from the drivers side, sounding from the #4 cylinder area. I have had piston slap on that side from the get go (rebuilt engine) but this just occured yesterday.

 

Performance has not been effected that I can tell.

timing belt tensioners can sound terrible and resemble rod knock or more sinister items. remove the drivers side belt cover and you'll be able to see it flopping around.

  • Author

Ok, just got back from pulling the timing cover off.

 

Fired it up and let it run. Little to no slap for about 5 mins. The idle lowered then the knock started but very inconsistant. The pulleys are sound and solid.

 

The knock is coming from #2 area and sounds more in the area of the valves. Didn't have a screwdiver long enough to get a better listen.

This is what happend to Blu before a rather impressive and spectacular rod failure.

 

 

nipper

Please sign in to comment

You will be able to leave a comment after signing in

Sign In Now

Account

Navigation

Search

Search

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.