Noisy diesel - PeterT
Following advice from HJ and others I am now the proud owner of a BMW 320 diesel. I am pleased with the car except for the engine niose which is much greater than the demonstrater that I tried. The dealer has had three attemts to quieten it by loading the latest software etc. but still no difference. Anyone any ideas how to proceed?

Noisy diesel - Armitage Shanks{P}
Try rejecting it under the Sale of Goods Act if it is really that bad and still very new.
Noisy diesel - Dude - {P}
Peter is this noise just on start up, or is it there when you are travelling? - Above 30 mph, my car is practically inaudible, and many passengers have been totally unaware that it is a diesel. Is your car an SE model and are you sure your vehicle is to full UK specification and not an import. I understand that one UK main dealer, which I don`t want to name, is actually supplying imports, which may be lower spec, with less sound insulation. If you can confirm that the vehicle is to full UK spec, then I can assure you, this is not the norm and I would reject it under the Sale of Goods act.
Noisy diesel - PeterT
Many thanks for your replies.

The car is a 320SE auto and may well be an import although the dealer advised that the specification was the same wherever it was sold. I haven't checked the sound insulation levels but I will when I next visit the dealer (Tues).

It is at its noisesest on cold start and improves with running. The engine noise appears louder than the courtesy car loaned to me both from inside and outside. I was wondering if the injection pump timing may be slightly out as this can make a big difference but I am not familiar with this particular engine.

Thanks again for your comments
Noisy diesel - Dynamic Dave
Did you test drive the demonstrator in warmer weather conditions than we're currently experiencing? Aren't diesels noiser when it's colder?
Noisy diesel - Oz
I go along with Dude. Mine (Y reg) is inescapably 'a diesel' when starting but not at all when warm and/or cruising.
Noisy diesel - Dave_TD
Even when it's -5deg C out, after 20 minutes your engine will be running at 90deg C, same as it will at 20deg C ambient temp. I still get looks of incredulity from passengers when they learn that my (basic model, £10k) Skoda is running on the slimy stuff, because the NVH has been sorted so well.
It would be worth comparing your BMW with another demonstrator. I'm not teaching anybody to suck eggs, but how much experience of modern diesel engines did you have before trying the "quiet" demo car? Could it be that the demo car wasn't as loud as your preconceived ideas led you to expect, and now you're spending some time in one you notice it more? Just a thought.
Noisy diesel - PeterT
Have had the engine looked at twice this week. All the parameters have been reset as well as injector balance, timing etc. The result is possibly quieter at speed but not at tickover. The Tech fellow admits its not quite right but as all the measurements are OK doesn't know where to go next. Any ideas?

Noisy diesel - Shigg
How about a louder stereo or ear plugs?
Sorry just come from the silly thread!
I suppose you could always try a diesel additive to see if that altered the burning of the fuel enough to quieten it down. Is it possible that the demo car had been altered from spec to make it quieter? Let's face it, a BMW has to sell on refinement above all else, so I think it's possible.

Noisy diesel - Dudley
Interesting! I run a Rover 218 SLD and have worried recently (an earlier thread) about a tapping noise that has appeared. My garage is sure there's nothing wrong with tappets but there's cerainly a noise like that (from my petrol car days experience!).

So is there something in timing or injectors that might lead to such noise?? I'd be very interested to know and perhaps then I need to take it to a diesel know-all to have a check.
Noisy diesel - Shigg
Personally I'd be tempted to live with it. In the case of your car I would assume that it a purely mechanical injection system and so pump timing can really only alter if the cambelt is changed and not put back in EXACTLY the same way, by which I mean a tooth/notch out on the injection pump or if it had 'jumped' a tooth. But if this was the case I'm pretty sure that you'd be looking at more than a tapping sound, sure the tone of the engine would change but I'd expect more/less smoke from the exhaust and better/worse performance.
Just out of interest have you tried a flushing oil just in case it is a sticky lifter?

Noisy diesel - Dudley
Thanks for the feedback Shigg. The noise had become noticable before the timing belt was recently changed. In fact, I had asked the garage to check the tappits but they said it was unnecessary, although they believed they were self adjusting hydraulic, and that conflicts with what my manual says!

Anyway, since the performance and smoke aren't problems, I'll try the flushing oil at the next 6,000 (I listen to HJ!) change.

But it's more rattly than it used to be - something is causing it. It used to purr, although pretty loudly. Now it rattles.
Noisy diesel - Shigg
For a car that really rattles listen to a Talbot Alpine, if you can find one! I'm sure rule of thumb was if it doesn't rattle don't buy it, it probably had it's valve clearences clamped down with the obvious long term effect this would have on the valves and seats.
Let us know how you get on after the flushing and new oil.



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