MamaKiddo Posted April 8 Share Posted April 8 Over the last several months, I have been experiencing an unusual rattling sound while the engine is cold. This sound is only audible when I accelerate, whether I am driving or at a standstill. The rattling noise is only there after I remove my foot from the accelerator pedal after accelerating, and not while I am actively accelerating. The noise entirely goes away after around 5 to 10 minutes. Below is a video clip demonstrating the noise. Please note that the video was recorded a few months ago and the noise has since worsened somewhat. The car is a 2018 model with a mileage of 50,000 km. It is equipped with a petrol engine. I would much appreciate any guidance or recommendations. Link to comment Share on other sites More sharing options...
CrawlerTagz Posted April 8 Share Posted April 8 Apologies, but I am unable to provide assistance since the situation does not seem favourable. Hopefully Johnny will promptly provide the solution. Collision. Link to comment Share on other sites More sharing options...
Markwe Posted April 8 Share Posted April 8 The noise seems to be originating from an external source rather than being connected to the chain. When someone revs the engine to produce the noise, can you observe the behaviour of the turbo wastegate? Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 I am unfamiliar with the turbo wastegate and its location. I do not hear any banging or rattling noises till I increase the engine's speed and only notice the sound after I let off of the throttle. Would the noise be audible even when the engine is not being revved if it was caused by a problem with the chain? I appreciate your assistance. Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 I have just been outside and captured an additional video, which may be seen here. The previously shared video was uploaded some months ago. Link to comment Share on other sites More sharing options...
Markwe Posted April 8 Share Posted April 8 The waste gate is the component in the video that exhibits reciprocating motion as the engine is being revved, and this movement corresponds with the accompanying sound. Link to comment Share on other sites More sharing options...
RosaStyle Posted April 8 Share Posted April 8 Perhaps the issue is with the crank damper pulley. Remove the auxiliary belt and temporarily operate the system to see whether the noise subsides. Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 Thank you for your input. Based on your judgement, it can be reasonably concluded that the chain is not in the worst possible condition. Is it OK to continue with our regular activities at this time? I have an upcoming MOT at the end of the month, so I plan to get it inspected at that time. If the issue is with the wastegate, is the repair cost high? I really value all of your remarks. Link to comment Share on other sites More sharing options...
Markwe Posted April 8 Share Posted April 8 Without direct observation, it is difficult to be certain, but I would find it unlikely that the chain is the issue. In 4-cylinder petrol engines, the waste gate is used to imitate the exhaust flap seen in 6-cylinder engines during cold starts. Therefore, due to the variation in engine speed, you may consider disconnecting the actuator and repeating the test to see whether the noise subsides. The fault light will be activated, however it should clear after turning the ignition off and on, I presume. Regarding the repair, it is uncertain if an adjustment or a turbo replacement would be necessary. Although I understand that your specific situation may not include the N20 engine, the underlying idea remains the same. I suggest doing a Google search for information on N20 wastegate rattling. Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 Thank you, Markwe. I really value your remarks. Is it okay to continue driving cautiously if the issue is with the wastegate? Since my recent relocation, I commute to the workplace twice a week, covering a distance of 60 miles. As a result, I now heavily depend on my automobile for transportation. I will request the garage to thoroughly inspect it on its MOT appointment. Can an independent mechanic inspect this or does it need the expertise of a BMW dealer? Thank you one again. Link to comment Share on other sites More sharing options...
Kenjibb Posted April 8 Share Posted April 8 Based on the first video, I would have identified the problem as either a chain guide issue or a tensioner issue. As said, disconnect the wastegate actuator, as seen in the second video, since it is directly related to the movement of the wastegate. Based on the video, it is doubtful that the issue is due to the chain. However, it is important to confirm that the problem lies with the wastegate rather than the chain. Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 Thank you, friend. Due of my lack of knowledge about autos, I will attempt to locate a someone who has the expertise to do a wastegate examination on my behalf. Is it possible to repair the wastegate without changing the whole turbocharger? If we assume that the issue lies in the wastegate, do you have any estimates on the approximate cost for replacement or repair? I am grateful for your assistance. Link to comment Share on other sites More sharing options...
Markwe Posted April 8 Share Posted April 8 Could you please provide your location so that we can see whether there is someone nearby who can help with troubleshooting? Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 That would be excellent! Located in Eastbourne. Thank you. Link to comment Share on other sites More sharing options...
Kenjibb Posted April 8 Share Posted April 8 Prioritise identifying the root cause by determining if it is the actuator or the presence of a loose coin causing the wastegate to rattle. Link to comment Share on other sites More sharing options...
Markwe Posted April 8 Share Posted April 8 If you are interested, I would be willing to inspect and listen to anything rather close to me in Wiltshire. It would not need a long travel on your part. Link to comment Share on other sites More sharing options...
MamaKiddo Posted April 8 Author Share Posted April 8 Thank you for the offer, my friend, but it is about a three-hour journey. However, I do appreciate your kindness. I will inquire with the garage to see if they can inspect it at the MOT appointment. Link to comment Share on other sites More sharing options...
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