335i Noises

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   Hi All,Have searched but could not find anything so hence my question.
Got 2006 335i with N54 twin turbo unit
Runs fine, good all round apart from an annoying rattle. At cold start up it rattles, like a very loud injection type sound. It does this for a couple of minutes then goes away once engine starts to idle. 
I thought it could be timing chain but it’s only on start up and not constant or re occurring.
Other thought was turbos.
Any ideas please.

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DrZeddy Members Profile Send Private Message Find Members Posts Add to Buddy List Forum Member Joined: 11 Apr 2023 Location: Kent Status: Offline Points: 5	Post Options Post Reply Quote DrZeddy Report Post Thanks(0) Quote Reply Topic: 335i Noises Posted: 14 Apr 2023 at 6:06pm
	Hi All, Have searched but could not find anything so hence my question. Got 2006 335i with N54 twin turbo unit Runs fine, good all round apart from an annoying rattle. At cold start up it rattles, like a very loud injection type sound. It does this for a couple of minutes then goes away once engine starts to idle. I thought it could be timing chain but it’s only on start up and not constant or re occurring. Other thought was turbos. Any ideas please.

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ON53Mike Members Profile Send Private Message Find Members Posts Add to Buddy List Club Member Joined: 27 Jan 2023 Location: West Midlands Status: Offline Points: 2	Post Options Post Reply Quote ON53Mike Report Post Thanks(0) Quote Reply Posted: 17 Jun 2023 at 11:15am
	One loud "rattling" sound that's common with the N engines can originate from the hydraulic valve lifters, it's a very distinct sound that people tend to compare to that of a diesel, although I think it sounds a lot more like a metallic tick than a rattle. A stretched or a loose chain can generate an excessively rattly sound, but I wouldn't of thought it was this because, as you say, the sound is intermittent. N54's are known for issues with the waste gate rattling, this one is easy to listen out for though, I have attached a video at the end. Another thing I can suggest is when the engine changes the operation mode of the injectors from homogeneous to stratified and vice versa, there is a good video on YouTube which shows the difference in the sound between the two - if you've never paid attention to your engine's sound before then this might also be it. Homogeneous vs Stratified Sound: https://www.youtube.com/watch?v=ssazqc63les N54 Waste Gate Rattle: https://www.youtube.com/watch?v=tkNF2G2cfZc
	ON53Mike