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Name That Rattling Sound!

SMOKEYV35

By SMOKEYV35,
in Engines & Forced Induction

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SMOKEYV35 Mentor

SMOKEYV35

Posted
Posted

hey guys,

car has developed a tinny rattling sound at idle. it seems to go away with throttle, and then as the revs drop it rattles again.

i got under the car and held one end of a screwdriver to everything i could think of, and the other to my ear - and i suspect it's related to the exhaust. it could be something simple like a loose heat shield or a stone caught behind a shield......but i'm also worried it could be something more sinister - like little bits of ceramic exhaust wheel bouncing around in front of the mesh on the cat converter.......

stock neo turbo has been running 11-12psi off the EBC.......is there any other way i can diagnose other than dropping the exhuast in front of the cat and seeing what comes out? its my first experience with a ceramic wheeled turbo, so any insight would be good!

for example, if the exhaust wheel does sh1t the bed, does it do it all at once, or will the blades break/chip off slowly.....? because the car is still boosting reasonably strong, only paranoia is making me question it....

cheers! Mat

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-_-StRyDeR-_- Experienced

-_-StRyDeR-_-

Posted
Posted

if the wheel hits the sides itll really break up, not just small chips...

might just be easier to undo the 2 bolts on the exhaust and see, get the car hot, and spray some WD on the bolts and let it cool down, then theyll prob be easy to undo.

just dont ruin the gasket lol.

11-12psi should be fine.

someone else might have some more insight/ideas

SMOKEYV35 Mentor

SMOKEYV35

Posted
  • Author
Posted (edited)

my understanding was that the heat of excessive boost is what kills the ceramic wheel - so you get hairline fractures forming on the exhaust wheel which eventually give way sending fragments flying off at 10000000rpm - i guess my question is - if that happens, will it automatically lunch the turbo - or is there a chance that only small pieces have come off and the turbo could still be functioning, just not at an optimal rate (slower spool). and that those small pieces could be what is causing the rattling, as they are stuck in the front pipe and blowing about in front of the mesh on the cat. could also explain why the sound goes away under throttle as they are getting blasted up against the mesh.

doesnt sound like i'm going to get a confident answer......looks like it'll be a case of getting under the car after work tonight. crap.

Edited by SMOKEYC34
ClutchBurndout-:( Grand Master

ClutchBurndout-:(

Posted
Posted
my understanding was that the heat of excessive boost is what kills the ceramic wheel - so you get hairline fractures forming on the exhaust wheel which eventually give way sending fragments flying off at 10000000rpm - i guess my question is - if that happens, will it automatically lunch the turbo - or is there a chance that only small pieces have come off and the turbo could still be functioning, just not at an optimal rate (slower spool). and that those small pieces could be what is causing the rattling, as they are stuck in the front pipe and blowing about in front of the mesh on the cat. could also explain why the sound goes away under throttle as they are getting blasted up against the mesh.

doesnt sound like i'm going to get a confident answer......looks like it'll be a case of getting under the car after work tonight. crap.

weather or not it is the wheel, might be a smart idea to take your dump off and check the condition of the wheel.

to my understanding (correct me if im wrong) the wheel is only coated in ceramic, so if the coating comes off the wheel can spool still, but the wheel is just smaller??

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

is boost response still the same? Does it feel laggier all of a sudden?

If so, loose actuator will let the gate "flapper" bounce around and can cause that noise. Common issue/tell-tale sign with hi-flows that use factory actuator so its plausible it could occur with a factory turbo as well.

Failing that - drop the exhaust @ the CAT and see what might fall out! :(

nuclear_skyline Mentor

nuclear_skyline

Posted
Posted

IF bits had come off the turbine you'd know about it. They're balanced pretty precisely and wouldnt last long at all if chunks, even small ones, were missing.

Drop the cat and see if its stuff and/or maybe the dump and have a look-see.

StealthX Veteran

StealthX

Posted
Posted

Hate to drop this to ya dude, but I'm gonna call - big end bearings.

A damaged bearing would sound like you're describing, with how it slightly goes away when you stab the throttle and up the revs.

I doubt it'd be turbo related.

nuclear_skyline Mentor

nuclear_skyline

Posted
Posted
Hate to drop this to ya dude, but I'm gonna call - big end bearings.

A damaged bearing would sound like you're describing, with how it slightly goes away when you stab the throttle and up the revs.

I doubt it'd be turbo related.

Thats true... Drop the oil out and see if there are any silver bits in it. If your keen run a magnet through it and see what comes out.

lachlanw Veteran

lachlanw

Posted
Posted

youd know if the exhaust wheel was gone . the car would be slow as fuc k and it would have dropped its guts when it you were boosting it somewhere.

my guess it its the rusty f**ked "heatshield" double skin what ever the f**k you call it that surrounds the front pipe before the cat . it rusts out and the insulation eventually f**ks off and you get rattles when your engine is idling at a certian frequency and the shit stops rattling above idle

what is your front pipe like?

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