Clinking sound when accelerating in BMW 330xi


#1

I have a 2001 BMW 330xi with 60K miles on it. A few days ago, the “Service Engine Soon” light came on and stayed on for a day or two, then it went off and has stayed off. Today (and this may be totally unrelated to the light but I wanted to provide all info) I started hearing a repeating “clink” when I accelerate. I did a little playing around and here are the characteristics:



- It is a repeated clink that varies in frequency with road speed, but not with engine RPMs

- It only is there when you accelerate

- It seems there are about 4 clinks per second at 20mph which is also when it is loudest. My math suggests this is one click per wheel rotation

- When the clink is at its loudest, you can just barely feel it in the driver seat floor like it is a mechanical sound coming from below the pedals.

- There are now no instrument panel lights lit.

- The clink is not there if you put the car in neutral and his the gas, only when actually moving. But it is also not there when coasting.



I haven’t had any service done except the oil that was changed (Mobil 1 0W40) about four weeks ago but everything had been fine in the interim.



Please help! this car has started having something wrong every 3-4 months starting just about a year ago and I’m fearing it is over the hill and I should just trade it in.


#2

I would suggest as a first step that you drop by a local AutoZone, Checkers, Advance Auto, etc. and have the scan the car for you. They will perform this service for you free of charge. Post any results back here for further discussion. Do not expect the counter help there to carry the diagnosis any further. That is not their job.

The “clink” sound is a bit puzzling to me but what I’m working on here is that this may be a pre-ignition rattle caused by a fault in the EGR system. A scan may show an EGR fault and this problem can be present even with the light off.