[Gatriel]

Hey everyone,

Wify came back to Frankfurt with her 2011 320d this past weekend from her 4 months in Switzerland (job related).

As we were leaving the house to run errands on Saturday morning we started from a cold start (about 3° C (37° F)) outside and everything sounded normal. We then leave the driveway and as we start accelerating up the hill there is a distinctive and new knocking sound we've never experienced before with this car.

While I do not have an actual video of it, it sounds very similar to this:

There is no loss of power (that is noticeable) and as soon as we level out the sound immediately goes away.

After the car warms up accelerating up other hills doesn't reproduce the sound.

The comments in the YouTube video indicated injector issues.

Opinions?

Best,

Gat

[nicklockard]

Editing for increased clarity:

I'm editing my post to clarify I mean leaking injector seal (the copper crush washers used to seat the injector's shoulders against the head), which allows cylinder pressure to escape. This is pretty common and makes that distinct popping noise. You can look for soot near injector seat (or have your mechanic look). If I'm right, a new set of copper crush washers and re-torqueing the hold-down forks will fix it. (So, a few bucks and maybe 90 minutes of your time.)

At first, my post just said "Sounds like an injector leak to me, too." which could easily confuse. Leaking injectors (such as dribbling or streaming fuel from nozzle tips and poor atomization or poor injection timing control is much more serious and can melt holes in pistons--but this failure mode has no such characteristic 'popping' sound. In this case, you'd get multiple error codes.

Sorry for the lack of clarity.

[335dsleeper]

Originally Posted by nicklockard

Sounds like an injector leak to me, too.

Can you describe the injector leak?

[nicklockard]

Gatriel,

Did you ever get this figured out or resolved?

[Gatriel]

Originally Posted by nicklockard

Gatriel,

Did you ever get this figured out or resolved?

Car is going to the dealer next week to fix water leaking into pass. side floor board and they are going to take a look at this as well. I'll post up what they figure out.

[glitdi]

Most likely an injector crush washer leak... The copper crush washer does not seal perfectly and will allow slightly burned fuel into the pass compartment.
Common symptoms are diesel smell, loud popping noise, and reduced power. Easy to find, look for moisture, black soot around the injector in question.
Funny enough I am going to do a little d.i.y. in the next couple of weeks on this exact problem once I get a few other peoples cars out of my shop...