Inconsistent Pulley Shake

[Jul4ster]

Greetings, everyone. The owner of a BMW E92 320d from the year 2010 has encountered a metallic rattling noise emanating from the pulley region of the vehicle. In an attempt to address this issue, the individual has replaced all pulleys and installed a new air conditioning pulley bearing. However, the power steering pulley, which lacks a bearing and is of a fixed nature, remains the only component that has not been replaced. The occurrence of a rattle is seen when the engine is subjected to a load without any revolutions. During startup, this rattle persists for a duration of two seconds. However, the rattle ceases if the air conditioning is on, therefore imposing a strain on the belt. Additionally, providing a little higher throttle while releasing the clutch or having someone stabilise the belt tensioner also results in the cessation of the noise.

The INA tensioner, Meyle water pump, air conditioning bearing, and alternator pulley have respective ages of three weeks and six months.
The Febi crank pulley is about one year old.
The power steering system was thoroughly cleaned. Upon manual rotation of the power steering pulley, it was seen that the pulley spins adequately but produces a clunking sound about every three-fourths of a full rotation. It remains uncertain if this clunking is within the normal operating parameters of the system.

The current situation is causing significant distress and assistance would be much appreciated. Greetings

[sarah_bentley77]

The potential causes of the observed noise might include timing-chain rattling or a damaged clutch bearing. Certain hoover pumps emit auditory vibrations.

The rattling sound may occur at a resonance frequency, which remains unstimulated when a load, such as the air conditioning system, is engaged and causes a tiny variation in the idle speed of the engine. Attempt to increase the engine's revolutions per minute to about twice the standard idle speed in order to ascertain if the issue resurfaces.

[BMW_Fan2020]

It may be inferred that the presence of noise is absent when the belt is not engaged while running.
I have not encountered a PAS pump producing a clunking sound of that kind previously. Typically, when manually rotated, these pumps tend to operate with little noise.

[Megan_Wilson88]

Attempt the task without the use of belts, as suggested.
I had previously encountered an instance of a rattling noise emanating from a fuel pump, although a considerable duration ago.
The positioning of the timing chain is often located towards the rear of the engine, therefore it is plausible that auditory cues may be indicative of its presence.

[Jul4ster]

Thank you for your response. The clutch kit was replaced 11,000 miles ago, while the chains were replaced 22,000 miles ago.
Today, I will proceed to remove the belt in order to investigate the possibility of reproducing the noise. It is worth noting that the noise does not occur during the first start-up phase of the day while the engine is warming up. Thank you.

[David_Smith2003]

Disregard the fact that I merely superficially analysed your message. It has come to my attention that you have made a modification to the crank pulley.
https://www.realoem.com/bmw/enUS/showpa ... Id=11_4085

[Jul4ster]

I would like to provide an update on the recent issue, which has since been resolved. Initially, there was a noticeable absence of noise when the belt was not engaged. However, upon further inspection, it became apparent that the dust cover was not properly installed on the alternator pulley. Despite the pulley appearing to rotate smoothly and maintaining a new appearance on the outer surface, it was discovered that rust had accumulated on the inner side. Removing the dust cover proved to be quite challenging due to its tight fit. Nevertheless, a new pulley was successfully installed, along with the appropriate dust cover, resulting in the restoration of silence. To be candid, I first underestimated the significance of not having the dust cover. However, over a period of six months, it became evident that this omission had significantly impaired its functionality.

[BMW_Fan2020]

Consequently, the clutch pulley had a seizure, so impeding its capacity to engage in freewheeling. I am pleased that the matter has been resolved.

[Megan_Wilson88]

I am pleased to hear that you have located the item and successfully resolved the issue.