Rattling Noise on e46 320d when accelerating

[Vince320]

Hi Everyone

I have recently purchased a 2005 model E46 320d with about 40 000 km's on the clock. Since receiving the car , the engine has been making a rather noisy rattling sound whenever I accelerate or the engine is under load. I have taken the car back to the dealership to get it sorted but they are clueless. First the said its normal "diesel knock", but I insisted as I have test driven quite a few other 320d's with similar mileage and they definately dont sound like mine does. In fact, the car is definitely not as nippy as the other 320d's I've driven.

Does anyone know what the likely cause is?

I am really frustrated with the dealership and it seems as though they are brushing me off because they would rather not have the hassle of seriously trying to pinpoint the noise.

Please help. I'm getting seriously pissed off as I have not been able to enjoy the car.

Vince.

[peterkulesza]

so no codes i take it? if the car was made in south africa: check this forum for specific problems with the 2 liter motor.

black smoke? rough idle? if so, could be a bad injector.

[Ocean02]

I had a similar problem on my Ford. It was my rear muffler bearing. It was sticking and backing up exhaust and sending a false signal to the hydrocilation module, thus causing the the exhaust bypass relief valve to close which made the car "hick-up".......okay, not really.

But honestly, I agree with Peterkulesza. Since the dealer couldn't find anything wrong, running codes probably won't show you much. I'm not much of a diesel guru, but it does sound like a fuel delivery or emissions problem.

What are the other symptoms other than the noise and funny sound? Any lights coming on your dash, etc.? Do diesels have O2 sensors?

Good luck!

[Vince320]

Thanks for the tips,

I'm a new BMW owner so I'm not sure what running codes are.
I haven't picked up any black smoke but I do think it idles a bit rough. There are no lights coming up on the dash so the only other symptom is the 'sluggish' performance at low revs. I know the turbo is only meant to kick in at about 1700 rpm but is it normal for there to be virtually no accelleration when I take a slow corner in second gear?

I think the car does have 02 sensors.

how do I search this forum for similar threads that might give me an answer?

[Vince320]

could you guys maybe spread the message to other members of the forum to see if they can help?

[bucketyed]

Hi
I had the same problem on my e46 325ci 01 when I first bought it. The garage eventually found out that it was the heat sheild around the engine had become loose and was rattling when underload.

[peterkulesza]

codes: these are diagnostic fault codes, stored in the car's engine management computer. your car uses electronics (injection/timing map) to figure out when, and how much diesel to squirt into the combustion chambers.

these codes usually last 50 start/stop cycles. hence, a bmw tech can interrogate the computer and figure out the problem.

2. turbo: it is spinning all the time (provided engine is runing). the amount of boost is of course dependent on the revolutions (and the consequent volume of exhaust gas. in my experience (a week or so of a 320d rental), 320d has NO turbo lag, so what you are describing can be abnormal. waste gate may also be electronically managed on your car, not sure.

this is a stick, yes?

3. search (painful, i know) for anything on 320d, cos i do remember similar problem being discussed in the e46 section.

4. i do not know anything about the emissions management of this motor, but it may be a factor. however, i think this is very unlikely: usually emission faults show up as check engine lights in the dash.

peter

[Vince320]

Thanks guys

Hopefully these clues will give the idiots at the dealership something to go on.