03-31-2020, 11:12 PM | #1 |
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M240i Rattle after Downpipe Install
Hi all.
I just installed a Catless DP (VRSF) on my M240i. The car is performing as normal, or even better. The issue is that on cold start, I hear a very loud metallic rattling/ticking sound, as if there's 50 metal BB's inside the DP. I confirmed the downpipe is not shaking, or rattling on any metal/shielding that's nearby. It only happens on the initial cold start, not when revving the car after it's finished the cold start cycle. If I shut the car back off and turn it on again, the same thing happens until the "cold start" is over. Any ideas? It doesn't sound like a wastegate issue nor is it the exhaust flaps in the back, it is 100% coming from the DP area. |
04-01-2020, 01:31 AM | #2 | |
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Posting here to keep an eye on this thread. Sorry about this issue! |
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04-01-2020, 02:20 AM | #3 |
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I have something similar with a Wagnar 300 cpi Downpipe.
It's not hugely obnoxious, but was the first thing I noticed on installing the downpipe. As you say, it's only on cold start. It made me worry that something was loose, and so I over tightened the clamp holding the DP to the turbo. Now the clamp has seized and I can't get it off, the nut spins in it's holder. I have bought a new clamp and will cut the old one off when I get an opportunity. I want to test the stock downpipe to see if the noise is still there, and then try catless. My theory has been that it's the waste-gate rattling with the reduced back pressure. That or some kind of acoustic resonance effect in the DP. If you modulate the throttle the tiniest amount, it stops. |
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04-01-2020, 09:37 AM | #4 |
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Check that your mid pipe isn't hitting the cross brace, the tolerances are pretty close. But that would be coming more from rear of the car. Also exhaust flap has been known to rattle.
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04-01-2020, 12:32 PM | #6 | |
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Good point about the waste gate being an issue, as throttle completely stops the issue. Really hoping for a solution here. I do not think it's the pipes themselves rattling. It's super odd. I'm debating bringing it into a highly rated BMW mechanic and having them diagnose, but I'd rather not spend $200 or more. EDIT: So I found an exhaust leak from midpipe to DP. fixing and will see if rattle persists. I would assume it will stay. Last edited by brandonfrancom2; 04-01-2020 at 01:43 PM.. |
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04-02-2020, 07:06 AM | #7 | |
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Did the VRSF DP make contact with the metal under tray? I installed mine (catless version) and was not able to get it seated without it making contact with the tray. I will have to try adjusting it again sometime soon. Everything else seems fine. No leaks. |
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04-02-2020, 01:40 PM | #8 | |
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I’m not sure what you mean by metal tray. There was one thin metal support bar running right under it I moved for installation, which after reinstalling has a decent bit of clearance. |
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09-26-2020, 12:09 PM | #10 |
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Hello, there is a solución for this sound?
I have the same sound from I installed vrsf catless downpipe to my m235i. Today I change the DP to MP clamp for a new one thinking that would be the solution. But the sound persist. I think that could be the turbo to DP gasket. I hope no. Here is a video with the sound. Only exist in idlle. Last edited by andres.psm; 09-26-2020 at 12:19 PM.. |
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10-23-2020, 06:58 PM | #11 |
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Start up exhaust sound
I have a 2017 M240i with a Dinan tune and a Dinan midpipe and a Dinan Muffler. All was good for about a two years then I am having the same issue with the sound at start up. It sounds like the exhaust is hitting the bottom cross over or tattling against something. I am not sure what the problem is either. I have had it back to BMW and they state the pipes are all tight. Let me know if you figure it out and I will do likewise.
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11-18-2020, 12:39 PM | #13 |
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I have the VRSF downpipe on my M240i xDrive and it does come into contact with the metal plate near where the exhaust connects to it. I've tried to fix it and it improved but I still get it if the car is stopped on an upward slope or if I put my foot to the floor while cruising.
One thing to note is I believe that metal plate is only on the xDrive model, not the RWD. I've pretty much given up on fixing it and am considering ordering a downpipe with the bracket and better fitment (ER is my current choice). |
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12-10-2020, 11:08 AM | #15 | |
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On the note of ER vs VRSF the ER pipe definitely seems to be much higher quality. Better welds, nicer flex pipe section, better bends. And I do feel better having that bracket even if it wasn't the source of my plate contact rattle. So for anyone with an xDrive model assume you will have to shim this plate for proper clearance. |
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04-24-2022, 11:32 AM | #16 | |
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Downpipe noise on morning start!
Hi andres.psm, you solved The problem?
I have this too Quote:
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04-25-2022, 01:10 PM | #17 | |
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04-25-2022, 05:47 PM | #18 |
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Don't have any rattles with our downpipe. You sure its not touching anywhere or its not the valves themselves?
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04-28-2022, 10:38 AM | #19 | |
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05-02-2022, 02:26 PM | #20 | |
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Drives: 2017 M240i xDrive
Join Date: Dec 2021
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I installed my AA downpipe and I have a rattle sound on cold start that stops after the cold start cycle. I'm guessing my midpipe is hitting the rear support brace? |
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09-15-2022, 01:21 AM | #21 |
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I also have a rattle on cold start that I can hear when Im driving as well. Any idea what this can be?
I had rattle before DP install, and I guess the catless DP just makes the rattle louder. I first thought it was the exhaust valve, but I changed it without success. It sounds like the rattle is coming from the middle of the car. https://youtube.com/shorts/Rj9Ch3rIdkA?feature=share Last edited by BMW335l; 09-15-2022 at 05:01 AM.. |
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