[JaiboCR]

Hi Guys,

Got my 335i 60k miles, making this grinding noise over 3k. Sound comes from the engine. Car is FBO. Makes the noise regardless the gear, even in P. No CEL. New oil 2k miles ago, has been solid, running wedge custom tune, w/m. Can it be the timing chain or something alike? Not sure at this point. Aside from this, loads PSI, shifts normally.

Please help.
Thanks!

[Emilime75]

Doesn't sound internal, but it's not good video/audio so it's hard to tell.

[JaiboCR]

Ita odd though as I sense its comming from the valve cover, but I also see what you are saying, as it would commonly be across the rpm range. Right?

[Emilime75]

Just think it sounds too loud and "sharp", and if it was internal it would be more of a "muted" sound, if that makes any sense.

Is it me, or does it sound like the rattle happens as you let off of the throttle?

[JaiboCR]

I let go because of the noise, but it really sounds when it hits 3k+... its like a grinding/bad pulley noise. Odd its over 3k. I have a feeling its oil related, but I dont have leaks and the thing says its at max. In the video it sounds kinda different than live. Sounds more like an impact driver once it reaches max torque.

[JaiboCR]

Started the car after being kinda cold again and notice some kind of fluid/air hissing noise in the oil hoses... can that be the noise of low oil pressure?

[E92William]

This sounds very much like a boost leak or vacuum leak of some sort. If it's not that it could be a pulley. Perform a smoke test and if that yields no results remove the expensive belt and check for play and free rotation of all pulleys.

[JaiboCR]

But, would the boost leak cause such grinding noise and just over 3k, even in N, where it builds no boost?

[E92William]

It sounds a lot like it, I've seen similar sounds from other n54s with boost leaks like say a pipe coming off or who knows. Do it with the ac compressor turned off

[iqraceworks]

Are you sure it's not waste gate rattle? Have someone stand over the engine bay with there head down by the motor and try to pinpoint where it's coming from.

[Emilime75]

Originally Posted by iqraceworks

Are you sure it's not waste gate rattle?

That was my first thought, also...or a heat shield. A better quality video would be helpful.

[iqraceworks]

What happens if you slowly rev it to 3000 rpms and leave it there.....does it still make the sound? Or is it only when you mash the gas really hard for a second where the turbos are trying to build boost?

[Jeff@TopGearSolutions]

Originally Posted by iqraceworks

What happens if you slowly rev it to 3000 rpms and leave it there.....does it still make the sound? Or is it only when you mash the gas really hard for a second where the turbos are trying to build boost?

I had same question.

[E92William]

With the engine cold, reach down on the exhaust side of the engine and by the exhaust manifold where the rear turbo is. There should be a rod. Grab it and shake it see if theres a lot of play. That means wastegate rattle. Some cars rattle on cold start others when revved up. Nature of the n54 lol

[Antetokounmpo]

Definitely not heat shield. Sounds just like a wastegate.