E39 M52 - Ratting Noise when stepping accelerator with air-con on

[sting936]

Hi Guys,

Just wondering if any of you have experienced the problem below with E39 M52 single vanos ride :

[1] Got rattling noise coming from engine compartment - identified to be near vanos area and compressor, and this only happen with the followings:
- Air-con unit is on
- Accelerating [even gently], normally happens when above 1,800 rpm
- When let go accelerator, the sound will slowly goes off, or
- Switching off air-con will remove it even when stepping on accelerator

[2] The sound is like putting a stick to a rotating fan [ruled out both fans - fans was suspected and has been changed]

[3] Compressor has been suspected but then it works fine at various setting when car is idling

[4] Run diagnostic and found Vanos to be at "Retard" when idle, and even when accelerator is step on to 2,500 rpm - Wondering if this is normal :juggle: ?


Any of you who got any clue or suggestion on what might be the problem?


Cheers and Have A Properous Lunar New Year !!

ST

 

[phil]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

you use 92 octone dont you

your car is either pinging under load or the air con compressor has a stuffed bearing

I bet its pinging

try 98 octane, tell me if it goes away

 

[sting936]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

I don't use anything below 95. Anyway thanks.

Am suspecting the Compressor, but strange thing is why only have noise when stepping on accelerator - air-con seems to be function pretty normal ?

 

[phil]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

becasue it puts strain on the compressor and the bearings make a noise

 

[sting936]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

Compressor is the next thing that I am considering replacing. Pretty expensive stuff with the original.

But then can it be the tensioner or belt slip ?


Cheers,..ST

 

[phil]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

belt slip will be a squeal,. not a rattle.

what does this mean?

4] Run diagnostic and found Vanos to be at "Retard" when idle, and even when accelerator is step on to 2,500 rpm - Wondering if this is normal

 

[sting936]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

This came about when my mechanic was troubleshooting the rattling noise. He at first suspected that the rattle may be caused by the Vanos unit. So he ran the diagnostic and the status for the vanos shows only "Retard". We were wondering if the Vanos unit is giving the problem.

And by the way, when you step on the pedal, what should the vanos status show?

I read somewhere that single vanos unit is an ON/OFF system [Advance / Retard] - is this true ??

 

[phil]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

mate, to be honest, i have no idea what the vanos unit is!!

But i think it is an air pump?

 

[sting936]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on

Hi Guys,

Just wondering if any of you have experienced the problem below with E39 M52 single vanos ride :

[1] Got rattling noise coming from engine compartment - identified to be near vanos area and compressor, and this only happen with the followings:
- Air-con unit is on
- Accelerating [even gently], normally happens when above 1,800 rpm
- When let go accelerator, the sound will slowly goes off, or
- Switching off air-con will remove it even when stepping on accelerator

[2] The sound is like putting a stick to a rotating fan [ruled out both fans - fans was suspected and has been changed]

[3] Compressor has been suspected but then it works fine at various setting when car is idling

[4] Run diagnostic and found Vanos to be at "Retard" when idle, and even when accelerator is step on to 2,500 rpm - Wondering if this is normal :juggle: ?


Any of you who got any clue or suggestion on what might be the problem?


Cheers and Have A Properous Lunar New Year !!

ST

I have forgotten to add that the noise does not come all the time even when air-con is on. It happens occassionally but once it starts, it will comes on more often when you accelerates [until you either switch off the air-con or lift your feet from the accelerator].

 

[suren2485]

Re: E39 M52 - Ratting Noise when stepping accelerator with air-con on



I have forgotten to add that the noise does not come all the time even when air-con is on. It happens occassionally but once it starts, it will comes on more often when you accelerates [until you either switch off the air-con or lift your feet from the accelerator].

Did you ever find the cause of the issue at all ?