E89 N20 Engine - Rattle Noise when Cold on Low RPM

[TomZ4]

Now with temperatures dropping down when I cold start my car I get a rattle noise around 800-1700 RPM when engaging the gear and accelerator gently on gears 1-3. It sounds like it's coming from the central air vent area, people hint me towards either timing chain, disa valve, heat shield and/or vanos bolts. I spoke with BMW service and they don't have any recalls for this model. Advice welcome.

Below is link to audio:
Skip to 1:15 - Starting on 1st gear from standstill
1:35 Right turn from low speed
2:10 - 2:25 - short starts with 1st gear slight engagement and slight acceleration
3:05 - acceleration and change to 3rd

https://drive.google.com/file/d/16oxrGcHlDipi11--eq64bv3J_UPxgmk0/view?usp=sharing

No other noise issues at idle or with engine heated up.

Cheers

 

[Smartbear]

Now with temperatures dropping down when I cold start my car I get a rattle noise around 800-1700 RPM when engaging the gear and accelerator gently on gears 1-3. It sounds like it's coming from the central air vent area, people hint me towards either timing chain, disa valve, heat shield and/or vanos bolts. I spoke with BMW service and they don't have any recalls for this model. Advice welcome.

Below is link to audio:
Skip to 1:15 - Starting on 1st gear from standstill
1:35 Right turn from low speed
2:10 - 2:25 - short starts with 1st gear slight engagement and slight acceleration
3:05 - acceleration and change to 3rd

https://drive.google.com/file/d/16oxrGcHlDipi11--eq64bv3J_UPxgmk0/view?usp=sharing

No other noise issues at idle or with engine heated up.

Cheers

That doesn’t sound like a cam chain noise to me, if it’s coming from the central air vent area I’d guess it’s got something to do with the ventilation fan & not the engine.
Have you tried driving the car with the fan turned completely off?
Rob

 

[TomZ4]

Yeah, this was recorded with aircon off and phone on that vent.

 

[Anonymous]

Yeah, this was recorded with aircon off and phone on that vent.

Aircon off is not the same as fan off

I agree with Rob..doesn’t sound like a cam chain..there is no DISA on N20s..

Possibly the vacuum pump which sits at the back of the engine and driven off the camshaft..but again sounds more like a metallic spring caught in a fan..

 

[TomZ4]

Took it to a RAC garage under warranty and the guy checked for heat shields and anything obvious. Couldn't locate the issue.

The suspicion now is DMF :headbang: Booked an Indy BMW for march for them to have a look

 

[TomZ4]

Bingo!

Thanks for help. Took out the AC fan out and the rattle noise is now gone.

The fan at the driver seat is not seized and looks perfectly fine so I will replace it, just to make sure there isn't any other fans/bits in AC system that are driven directly by air pressure?

https://ibb.co/Dk3T2Jj