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Discussion Starter · #1 ·
Hi I have a 2018 Focus ST and a few months ago I started hearing a metallic rattle sound underneath when I coast in any gear or decelerate. It’s loud but not too loud and only happens when I coast, it doesn’t happen on throttle. I have a Cobb Catback Exhaust and had it for almost two years now. I looked underneath and tried to see where it was coming from and it seems to be coming from the same part on the image. I think it might be a lower intercooler pipe? Anybody else had this issue? I don’t think it’s heat shield because it comes exactly from this pipe. I’ve even taken it off and inspected the inside to see if metal was torn off and rattling but it looks good. Possible exhaust leak?
 

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Is the exhaust the only thing you did to the car? Are you the first owner?

Did you ever change the exhaust hangers? I'm thinking from the information provided is that it might be the exhaust rattling. I have the same exhaust but I've changed the hangers as well and I've never had any rattle sound.
 

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Could be a heat shield, I had an MBRP and the first year it didn’t make a noise then it started rattling and it turned out to be the heat shield, I just pushed it back with a crow bar and haven’t had the issue since

edit- ok read full text saw you say it wasn’t a heatshield, check to see if there is any fresh exposed metal next to that pipe to see if it’s been clanging around
 

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I doubt it is the hot charge pipe, since you removed and installed it. The dp bracket is more like it, since it seems to be coming from the “engine area”.
 

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Discussion Starter · #6 ·
Is the exhaust the only thing you did to the car? Are you the first owner?

Did you ever change the exhaust hangers? I'm thinking from the information provided is that it might be the exhaust rattling. I have the same exhaust but I've changed the hangers as well and I've never had any rattle sound.
I also have a Cobb cold air intake and a Cobb accessport with a Flash tune from stratified auto. I’ve also changed the hangers with the Cobb hangers so it’s not that. I inspected the car this morning and put it on a lift and I used a stethoscope and the noise seems to be coming from the turbo instead.
 

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Discussion Starter · #7 ·
I doubt it is the hot charge pipe, since you removed and installed it. The dp bracket is more like it, since it seems to be coming from the “engine area”.
I put the car on a lift this morning and used a stethoscope and had someone rev for me and i hear the noise seems to be coming from the turbo instead. Any ideas what could be rattling? I’m thinking a turbine is loose? It seems like the rattle is caused by something spinning so that’s my guess
 

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2014 ST3. Garrett Powermax turbo, Thermal Turboback, CPE intercooler, JBR intake, Innovative RMM
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It seems weve had a couple recent instances of the wastegate flapper making noise from a few posts i've come across. If it's bad enough to make the noise after a rev, you could have someone rev the car while it's lifted and use something like a long prybar to put pressure on the wastegate arm and see if the noise goes away.
 

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I don't hear anything abnormal from the engine bay shot. The rattle upon rpm's dropping from the exhaust shot is a noise my Thermal exhaust makes. I think it's just the muffler packing rattling around a bit. But in my instance its coming from inside the exhaust.

If thats not it, and it isnt just coming from inside the exhaust, can you place the camera under the car on the ground closer to the engine bay and get another shot? Im thinking somewhere under the driver's foot well.
 

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That does sound like the flapper issue, jack it up and do what i was saying with the prybar (gently) Against the wastegate arm while someone else revvs it. If the noise goes away, you've found your issue.

No reason to sell the car over! You'll Get it figured out!
 

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So the wastegate rod has play at the point where the two nuts should be locking it set. I haven’t ever touched this part myself but I know about adjusting the preload but haven’t done it yet. Lightly jiggles around ??? I dunno 🤷‍♂️ Is it normal?
 

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Im gonna have to take to it ford. Could the wga solenoid be making that much noise? The car seemingly drives just fined and makes good boost. Just that noise in the decel is horrible! I worked the action of the wastegate and it didn’t seem to affect anything noticeably?? Ugh I’m lost I might just go to the dealer.
 

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Any news on this? I have a 16 fost that just started doing this exact thing. Makes a metallic rattle sound on decel or coasting, never on acceleration. I too believed it to be wastewater flapper, as I've heard of issues with them on the stock turbo.
 

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I have a rattle also coming from my turbo i was told my wastegate was messed up. I just ordered a wastegate actuator to hopefully fix it. But the wastegate it self is internal. Could be cracked on inside of turbo
 

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I have a rattle also coming from my turbo i was told my wastegate was messed up. I just ordered a wastegate actuator to hopefully fix it. But the wastegate it self is internal. Could be cracked on inside of turbo
I answered your other post in the other thread, but the rattle usually comes from loss of preload from the bushings wearing out. See post #24 in this thread.

 
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