# Strange "Diesel" sound recently (N57)



## ImolaRedM (May 20, 2013)

Has anyone else one day suddenly experienced more of a diesel sound from their N57? My 2014 535dx (aka 530dx) has suddenly developed a loud diesel rattle at idle. It's barely noticeable with the radio turned off and windows closed. But crack the window at a traffic light and it sounds like I'm next to a Diesel F250 until I drive off. The car drives fine and it's not throwing any errors so I'm inclined to wait and mention it to the service department when I'm in for my oil change in a couple of weeks.


----------



## Flyingman (Sep 13, 2009)

Sounds are funny things. What is normal, abnormal?

I recall our engines have some sort of an air filled engine mount that "adjusts" with load so it isolates the engine more at idle than at highway speed.

I know little about it other than others have posted problems and discovered the air line that operates it was pinched or somehow not allowing it to work properly at idle and were experiencing more noise/vibration.

That is about the only pointer I can come up with, unless your hood is open, and I assume you would know that.


----------



## F32Fleet (Jul 14, 2010)

Was it cooler than normal? I wouldn't worry about it really if it's just a one off event.


----------



## ImolaRedM (May 20, 2013)

I was thinking about the temps too but it's louder than when the temps are cool and the engine is cold. The temperatures here have been going up and the engine was warm so I wouldn't expect it to be temperature related. It seems RPM (resonance?) related. It's been going on for a few days now so I don't think it's a one-off.


----------



## ImolaRedM (May 20, 2013)

Turns out it's the power steering pump. Never heard a power steering pump make that kind of noise. I took it in over a week ago. I was traveling out of the country for business so I wasn't terribly upset about waiting so long for a part to be sent from Germany but I received an email saying that the part was damaged and they need to re-order the power steering pump. I hope to have my car back by the end of the week.


----------



## ImolaRedM (May 20, 2013)

Okay, finally have my car back today. Turns out it wasn't the power steering pump after all. There are a handful of 2014 535d's in the US(?) that have a problem with an aluminum pulley on the power steering pump. A TSB came out on the 13th that listed a small handful of VIN's and mine was one of the last VINs on the list. Replaced the pulley with a steel one and all is good again.


----------



## Flyingman (Sep 13, 2009)

I have a hard time imagining why an Aluminum pulley wheel would cause some noise vs. a steel one?:dunno:

You weren't having the famous A/C belt screech were you?


----------



## ImolaRedM (May 20, 2013)

Flyingman said:


> I have a hard time imagining why an Aluminum pulley wheel would cause some noise vs. a steel one?:dunno:
> 
> You weren't having the famous A/C belt screech were you?


Quite certain it's not a belt screech. This was definitely a taping sound almost which is why I questioned the diagnosis that it was the pump.

I didn't get to see the pulley but how it was described to me makes sense. The aluminum pulley couldn't stand the stress under load and the bolts started wearing into the pulley cutting a pattern into the aluminum. Under idle, there was slop that became progressively worse causing the knock or ping sound but under load the sound would go away. The steel pulley is stronger and prevents the bolts from cutting into the aluminum.

There were only a handful of car affected so I'm not sure if the new(er) engines have steel pulley or if they used a heavier aluminum pulley and added more bolts to the pulley to handle the load.


----------



## 335dFan (Nov 8, 2012)

ImolaRedM said:


> Quite certain it's not a belt screech. This was definitely a taping sound almost which is why I questioned the diagnosis that it was the pump.
> 
> I didn't get to see the pulley but how it was described to me makes sense. The aluminum pulley couldn't stand the stress under load and the bolts started wearing into the pulley cutting a pattern into the aluminum. Under idle, there was slop that became progressively worse causing the knock or ping sound but under load the sound would go away. The steel pulley is stronger and prevents the bolts from cutting into the aluminum.
> 
> There were only a handful of car affected so I'm not sure if the new(er) engines have steel pulley or if they used a heavier aluminum pulley and added more bolts to the pulley to handle the load.


Of course you know your mpg will decrease because of all that extra weight.


----------



## Flyingman (Sep 13, 2009)

Interesting. Always more to the story.

Still amazing that the engineers would make a mistake like that, but it happens to the best of them.


----------



## ImolaRedM (May 20, 2013)

335dFan said:


> Of course you know your mpg will decrease because of all that extra weight.


Yup, that thought immediately crossed my mind. I'll probably see a .02% reduction in MPG but then the wobble from the aluminum pulley probably had a negative impact as well. 



Flyingman said:


> Interesting. Always more to the story.
> 
> Still amazing that the engineers would make a mistake like that, but it happens to the best of them.


Considering the list of VIN on the TSB, it's a small mistake. When the SA told me mine was one of the last VIN's I assumed he meant one of the last in the range. He showed me the TSB and it was literally a few (less than 12 more than 6) individual VIN's on the list. Compare that to a TSB from other manufacturers where there is a range of VIN and yours always happens to be just outside the range with the same symptoms. I'm happy BMW has been good about addressing these problems over the years. I can't say the same about some of my other vehicles.


----------

