rattle from a/c duct
 

I have a 2000 ML 320, purchased in April this year, coming off of a lease.

I have not had any major problems, outside of the steering rack being replaced under warranty, because of a "popping" noise when turning the steering wheel when the vehicle was stationary.

I do have a "plasticy" sounding rattle which seems to be coming out of the passenger side a/c vent in the dash. It sounds like a baby's rattle, or perhaps a stack of plastic lunch forks jiggling around, every time I am on a gravel road (constant) or tar strips, or railroad tracks (intermittantly, consistant with the sudden jolt of crossing the tracks)

It does not seem to be the vanes in the vent. Nor is it effected by opening or closing the vent. I have looked into the vent with a flashlight and see nothing.

There is a wealth of information on these boards, so I thought that I would ask here, before I take it to the dealer. I would rather try to fix it myself, rather than having to deal with the "unable to duplicate" routine.

Does anyone have any guess as to what might be causing this?

Thanks!
George

Just a thought but you might want to take the plastic panel off below the dash, the one that gives you access to the pollen filter, when you change it and see if there anything in there that looks suspicious . You could also take the glove box out to give you more access to the area where the noise is coming from. If nothing is obvious I'll have my wife drive down a somewhat bumpy road and scrutinize the problem area visually I'd also push and pull on some of the plastic pieces up in there to see if the noise stops.

I had an annoying creak in my dash that turned out to be from the contact the radio made with a part of the plastic bracket that it rested on, problem was cured with some two sided tape and duct tape.

Good luck tracking it down.

Thanks Ron,

I tried to take out the glove box, it too has been replaced as a minor warranty item, but alas I did not have the (is it torx?) driver to remove it. I will need to get one of those driver sets. I had one, but the design was not so good, and all the drivers fell out of the handle, some into the lake.

Thanks for the input. This is a real "lightweight plastic-y rattle" I cannot imagine what it could be, unless it is something lightly resting on the ductwork, that rattles when jolted, and the duct is just transmitting the noise into the passenger compartment.

Thanks again,
George

I have a rattle that sounds exactly like your description, also in a 2000 ML320. Mine just started coming from the center vent closest to the driver. Any help in identifying the source will be appreciated.

RossMc,

The noise I had also sounded like it was coming form the center vent. It turned out to be from the radio as I described above. You might want to check that out. Just remove the radio and see if the noise stops. Plus once the radios out you can get a good look at what's going on in that area.

One note, you will have to re-enter the code for your radio when you reinstall it, no problem though the number is with your owner's manual and the little cover that it comes in.

Thanks for the tip on the noise coming from the radio. Can you provide any directions for removing the radio? Are special tools required?
Thanks.

Crutchfield sells a radio removal tool for about $10. Of course to make it work again you'll need the code.

You can also get the tools from your dealer or by calling Becker North America, check their website.

The two little pieces of thin flat metal slide into the little slits on the bottom of the radio and the radio will pull straight out very easily. Of you course you need to disconnect the plugs and the like from the back of the radio.

If you want to see what these little things look like they have them for sale all the time on ebay, I think they call them Becker radio removal tools. I'm thinking the ebay prices for these are a little high but I really not sure.

Further testing
 

I removed the glove box, and also the panel covering the pollen filter. I cleaned out the filter, and reinstalled it. Feeling around under the radio, I found some wires that might be tapping on plastic on bumps, and put a small towel in there to keep them from being able to jiggle against the plastic. I then went on another test drive with the glove box, and cover still removed. It seems that my "noise isolation device" had been malfunctioning previously. He now says the rattle is coming from the "A" pillar on the passenger side. Is there a bundle of wires that run down that pillar? How do you remove that fabric covered pillar cover? I pulled the weather seal back and peered in there, but did not want to break any little plastic bits/clips, etc.

Thanks again, and I am sorry for the mis-information in the original post, concerning the location of the rattle.

George Mobbs

Rattles behind the radio and MCS units are pretty common for ML's. What I have found the most is gps, tele, and fiberoptic
cables banging around on the instrument panel carrier and heater
box directly behind the head unit.
Some felt tape and cable ties has always done the trick for me.
DR.D

Also check the noise panels under the engine and transmission.