Does my 240D sound healthy to you? - PeachParts Mercedes-Benz Forum

DieselAddict · #1 02-09-2007, 04:21 PM

I'm running about B50 right now which has toned down the combustion noise but helped reveal another engine noise which is audible in this sound file. Can you hear it? The noise has always been there as far as I remember regardless of the fuel used, it's just that on regular diesel fuel the louder combustion noise somewhat masks the other noise. What do you think of this sound? If anyone else has a sound file of a 240D idling (preferably warmed up), I'd like to hear it to make a comparison.

TheDon · #2 02-09-2007, 04:33 PM

Something is rattling.. Thats what it sounds like to me..

toomany MBZ · #3 02-09-2007, 05:00 PM

Doesn't sound too bad to me.

300SDog · #4 02-09-2007, 05:24 PM

That sounds to be possibly piston slap and could be caused by incorrect Injector Pump Timing. And have you had injector pump timing done lately? At about 167k miles IP timing made a world of difference with mine.

kerry · #5 02-09-2007, 05:43 PM

Sounds ok to me.

pawoSD · #6 02-09-2007, 05:47 PM

Sounds fine to me too....I can hear the sound you're talking about....but it just sounds like a rattle.

300SDog · #7 02-09-2007, 05:53 PM

Not the normal happy valve train clatter, but the undercurrent slap, slap chatter.... that's probly what he's wondering about.

punky · #8 02-09-2007, 06:01 PM

Sounds perfectly normal to me. I've been listening to mine for 3 years now, 7 days a week. I'm starting to think that these little 4 bangers are almost organic creatures. Each one having it's own particular tone or pitch and timing. I must say, since ULSD mine has sounded like crap under load. Still have the same power/torque which is confusing. I mean, I climbed a short familiar hill today using 4th where I've always used 3'rd before. Kept the same speed as if I were using 3'rd. So many things have happened at once this year, i.e. frigid temps/ULSD. I'll hold out till spring and see what happens.

300SDog · #9 02-09-2007, 06:10 PM

Yep, probly a good idea to hold out for warm weather before negotiating diagnosis with diesel engine. The happiest of my 240D's seems to bubble and pop at warm idle in summertime, yet naturally feels rougher in winter.

And that's true - being normally asphixiated self-combusting engines each must be treated on individual case scenario basis. Still I'd jump all over an IP timing adjustment, given the mileage.... not quite at replacing the timing chain, but close.

DieselAddict · #10 02-09-2007, 07:39 PM

Thanks for the responses so far. Keep them coming. Here's another sound file from a different angle but recorded at the same time as the other one. I feel in this one that sound is less audible.

I did do the drip timing about 2 years ago and it seemed spot on so I didn't adjust it. The first time I noticed this sound was when I did a Diesel Purge shortly after pop-testing my injectors and replacing two of the nozzles. I don't know if that has something to do with it. What I do know is that it seems to be related to the #4 cylinder. I didn't always have those injector pipe clamps installed and the noise was much louder back then. Touching the #4 injector pipe reduced the noise a lot, though not completely. That's why I installed those clamps which have a similar dampening effect as my finger. Unlike with a combustion knock, the cetane index of the fuel doesn't seem to have any effect on this sound. That's why it's more audible while running on bio or DP.

DieselAddict · #11 02-09-2007, 09:50 PM

Just to clear things up, yes, I'm wondering about the "slapping" noise, not some rattle or similar background noise. Any more ideas or comments?

retx · #12 02-09-2007, 10:55 PM

just wondering...is that a still or an actual video? i wish my engine would be that smooth. sounds about like mine. i have some weird slapping sound too.

#13 02-09-2007, 11:28 PM

Sounds fine to me.

86560SEL · #14 02-09-2007, 11:30 PM

Sounds fine to me! I love it!

2.5Turbo · #15 02-09-2007, 11:40 PM

It's a still, notice the date stamp in the lower right corner.