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Guest Message by DevFuse

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Piston slap

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4 replies to this topic

#1 mdjdc


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Posted 14 August 2007 - 05:46 AM

I am new to the legacy line so bear with me. I have a 1999 outback wagon and I have begun to notice a tick when I first start up the car. Once it is warm or the car has been driven several hundred yards the noise is gone. Is this piston slap or valves out of adjustment?

What is piston slap and how serious a problem is it. The engine has 193k on it right now and is the original. What other potential issues do I need to worry about.

I also have a 1996 outback that makes a noise when the auto tranny is shifting. Sounds like a quick rapping noise. Is this piston slap or do I have a rod bearing going? I'm thinking about a japanese pulled motor for repoacement and want to know if I should bother.

By the way, both cars have the 2.5 DOHC engine.


#2 idosubaru


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Posted 14 August 2007 - 07:46 AM

for the 99 it sounds like piston slap. the piston slap should not cause any failure, it doesn't typically.

other issues - 2.5's have headgasket issues, i'm guessing you know about that.

#3 porcupine73


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Posted 14 August 2007 - 07:56 AM

For the '96, it might just be the TCU applying the clutches and such to do the shift. It doesn't just slam the solenoids from off to on, it goes from 0% to 100% duty cycle at 50Hz and this can cause a brief audible buzz.

For the '99, Engine Noise When ColdThe Subaru Technical Support Line has received several reports from the field of an engine noise that could be mistaken for an internal engine noise on 1999-2000 Impreza, Legacy and Forester models equipped with 2.2 and 2.5 liter engines.

The noise sounds like it is coming from the front of the engine and could be mistaken for failed bearings. This noise is heard after a cold start and will gradually go away as the engine warms up. It may therefore be difficult to reproduce the noise unless the vehicle is left overnight.

It has been found that the timing belt tensioner on these vehicles may be weak, allowing the timing belt to move and hit the inside of the timing belt cover.

The tensioner bearing itself could also be at fault. It is essential that you listen to the actual noise before reaching a diagnosis. If you suspect the belt tensioner, remove the front cover and look for evidence of rubbing or chaffing. As the vast majority of these vehicles will still be covered by the manufacturer’s powertrain warranty, any vehicle exhibiting these symptoms should be returned to an authorized Subaru dealer for service.

#4 nipper


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Posted 14 August 2007 - 09:51 AM

Lots of similar threads on the bottom of this page cover piston slap.


#5 forester2002s


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Posted 14 August 2007 - 10:35 PM

Lots of similar threads on the bottom of this page cover piston slap.

Hey, I've never scrolled down to the bottom of the page to see the 'Similar threads' listing.
Thanks for the tip.

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