fallwood

My 01 (35,000 miles) wrx has developed a strange rattle from the downpipe/turbo area, I originally thought it was one of the heat shields rattling so didnt pay much attention untill it pissed me off the other day and I decided to investigate. Took it to my local scooby mechanic and after much looking and reving decided that the only way to determine the source would be to take the turbo and downpipe off and see whats going on in there. The rattle only occurs when the throttle is blipped at very low revs and only occurs as the revs fall off, no rattle when revs are held constant and no rattle at high revs. Suggestions ranged from wastegate chatter to a foooked turbo although it drives fine and uses no oil. Any ideas anyone as I'll be well pissed off if it turns out to be the turbo thats died alredy.

JPS3290

Hi. Cant really help but im suffering from a very similiar problem on my 02 STi with 31.5k on the clock. No loss of power from the turbo, cars driving same as normal and not using oil.

My rattle sounds like its coming from about the turbo area, maybe lower and all the heat shields are fine including manifold ones, although it does sound like a heatshield type metallic rattle.

Mine does it after engines been ran for a minute, never when stone cold. It then does it when idle although can only just be heard. When revved it gets louder and louder and sounds horrendous. My local scooby garage listened to it for 30 mins and at the time he first throught it was the rear of the turbo maybe catching on the exhaust manifold as the bearings could be giving way!! Then noticed the clutch was very hard to press (i thought it was normal) and it had a harsh vibration coming through it. When depressed the noise seemed to go completely. So now thinks its very likely to be the release bearing in the clutch.

Not sure if that would travel up and make the sound come from the turbo area though? Its so hard to diagnose exactly where its coming from. Putting a screwdriver on the turbo and other end to your ear you dont hear the noise.

And now pressing the clutch doesnt seem to make the noise go away, although it doesn quieten is slightly.

Anyway, its going in to have a new clutch kit fit on Tuesday so will let you know what the result is if your interested? If yours is sorted before them please let me know!

fallwood

Took the car in today for further investigation and the news is good, they dropped the downpipe off and removed the turbo, all is fine with the turbo/actuator . Apparently the noise is coming from the pre-turbo cat (in up pipe) ,one of ceramic honeycomb bits has come a bit loose and is rattling at certain revs, mechanic said he was 99% sure this was the prob but without removing it he could not be 100% sure, as it takes 4-5 hrs to change this cat I decided that his 99% diagnosis was good enough. Now im a bit worried that if the cat starts to disintegrate it will damage the turbo, if it doesnt will an empty cat be the same as a cat replacement pipe. At least the turbo's not foooked, at least ill get to sleep tonight.

JPS3290

Thanks for the reply. That is what it sounds like isn't it. Like the ceramic in the cat has broken away and rattling around. Think i'll get them to check that before taking the gearbox out to replace the clutch

Would of thought the cat would of lasted longer than that though!

fallwood

Yes so would I, mines only done 35,000, 1st cat thats ever gone on me , would have to be the most difficult one to replace ,LOL.

JPS3290

Spoke to the mechanic who's doing my car next week and he doesn't think mine is the Cat although will check it when its in before taking gearbox out. He said mines not a rythmic noise that a failing cat would make so seems unlikely to be the cause of my noise. Mine rattles going up or down the revs at the same speed no matter how high its rev, it just gets louder not faster or slower which a failing cat normally makes.

So he reckons mines still a knackered release bearing. Will report findings on Tuesday when its been in all day