Distinct rattle between 500 to 1000-1200RPM

L1ND4

L1ND4

Member
 Sydney
Hi All,

Here we go!
I am hearing a metallic rattle from my Z4 E85 M54. Engine.
This rattle can be heard upon cold start especially (heard throughout drive though) and only ever between 500 to 1000-1200RPM, making it particularly apparent in stop and go situations.

The rattle is also heard when in reverse gear.

In the month of March I have
• Replaced air intake boot leading into manifold
• Replaced air filter and cabin filter - one of them was still factory!
• Replaced all 6 spark plugs - now with appropriate NGK plugs
• Replaced all 6 ignition coils with OE Bosch coils
• Replaced DISA valve today - mechanic assured me this was the problem after ‘failed’ smoke test.

I noticed this rattle after initially replacing the spark plugs and air intake boot. The rattle persists.

Your ideas and input are appreciated😀
 
I would have also assumed DISA from your symptoms.

Another to consider would be the vanos unit may need a rebuild. Not a big job on these engines, unlike the S54's.

Have a look at some YouTube videos to see if the sound is the same?
 
Agree it could be the rattle rings in the vanos

What mileage and which engine size is it?

Can you get someone to rev the car to create the rattle and listen to the vanos area to confirm?
 
Rattle rings I’d agree with.
But if it only does it under load it could be pinking due to a weak mixture.
If not under load then you can try the old screwdriver trick against the various suspected areas and see if you can hear it better and identify where it’s coming from.
Not something simple like a jubilee clip left loose after doing the intake boot?
 
I’ll try the screwdriver trick to locate the rattle, although the sound is hardly noticeable at idle.
All clips have been tightened.

Same mechanic that misdiagnosed the DISA valve has advised me to remove and refurbish fuel injectors.
 
L1ND4 said:
I’ll try the screwdriver trick to locate the rattle, although the sound is hardly noticeable at idle.
All clips have been tightened.

Same mechanic that misdiagnosed the DISA valve has advised me to remove and refurbish fuel injectors.
Click to expand...
Why listen to them after the first misdiagnosis
 
Check your chain tensioner. It is hydraulicly assisted spring loaded. At low oil pressure (low revs) it relies on the spring to tension the cam chain. If it's this you will clearly hear or feel it at the front of the engine near the valve train. You just need someone to work the throttle.

After installing cat cams I had this problem and we changed out the vanos ,added an anti rattle kit and a new m54 chain tensioner. Nothing helped until I read that many people install the s54 chain tensioner. Bingo. Noise gone.
 
Last edited:
Hi All,

*UPDATE*

Thanks for your input and suggestions.

The problem has been diagnosed and remedied by a local Euro car specialist.

My serpentine belt tensioner was failing and has been replaced. Associated symptoms are gone. Good. Gone. Period.

I will not be returning to my long time mechanic of 10-15 years.

Thanks.
 
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