Bird sound, fluttering when pressing or letting off accelerator - PeachParts Mercedes-Benz Forum

Marrs · #1 03-31-2013, 09:19 PM

Hiya, I'm not sure if my car always made this sound or if I am only noticing it now that I got some of the loud stuff fixed but I hear what sounds like a nest of birds or someone sipping bubbles through a straw. It only happens when the accelerator is loose, by that I mean no sound under idle, when I press the pedal down nothing, or when it is springing back up nothing, but when I press then let off to coast that's the only time it happens. Basically anytime the pedal has no foot or spring force exerted on it the car makes the sound, and it is coming from somewhere other than the pedal itself like engine bay or under the car.

What could this be?

shadetree77 · #2 03-31-2013, 10:24 PM

check for birds nest under hood! lol, j/k. maybe a vacuum leak?

Adv_rider · #3 03-31-2013, 10:43 PM

Loose belts?

Coastal220 · #4 03-31-2013, 11:50 PM

Loose linkage?

Marrs · #5 04-01-2013, 12:09 AM

Not belts, but what vacuum leak could it be that it happens only like this? I don't have any symptoms of vacuum leak that I know of but it's possible.

Linkage may be possible, so you think maybe it's just sort of rattling against something when it's not taught? That seems pretty close to what I am hearing actually, will check it out, thanks!

280SE Guy · #6 04-01-2013, 04:13 AM

I don't know what that sound could be, I don't see it on the repair estimate price list:

Regards,

280SE Guy

Marrs · #7 04-01-2013, 12:55 PM

That's great 280seguy! lol

Does anyone have a scan or info specific to adjusting the linkage on my car? I've found these two similar threads but need one that I can specifically refer to. I thought I could just replace some bushings maybe but it seems there is a spec for the length of the rod adjustments. Thanks!
http://www.peachparts.com/shopforum/vintage-mercedes/320907-w108-4-5-sticky-throttle-brakes.html
http://www.peachparts.com/shopforum/vintage-mercedes/267416-72-280se-4-5-throttle-control-linkage.html

shadetree77 · #8 04-01-2013, 10:57 PM

i just threw in that vacuum leak idea since a gas engine has high vacuum when coasting; i really only deal with diesels now, sorry

Palolo · #9 04-02-2013, 01:34 AM

Guaranteed the one "bird sound" a Benz, even a tiny little baby Benz, will never make: cheep-cheep-cheep

dirtyharry · #10 04-02-2013, 10:46 AM

its the transmission... or associated spinning things... flex plate, drive shaft, etc could be caused by bad motor mounts or movement in the drive train its not necessarily a bad thing... or could be the exhaust.

Stretch · #11 04-02-2013, 12:00 PM

Did someone fit a turbo whilst you weren't looking?

Marrs · #12 04-02-2013, 04:50 PM

Quote:

Originally Posted by dirtyharry

or could be the exhaust.

Tell me more, what aspect of the exhaust? I'll check the rubber underneath while I'm down there, I have an auto box and I know the shifting is related to the accelerator linkage rods and they must be correct, so once I find those specs I'll start there but want to consider all options.

Stretch: Maybe that's the newest fad, these kooky street kids putting turbos in unsuspecting driver's cars to upload to their got-danged youtube cameraphone xbox.

Cheep-cheep-cheep... I disagree, the air in the tires was only $1, but it is aftermarket.

Palolo · #13 04-02-2013, 06:45 PM

That cheap aftermarket air sounds like a snake when it goes bad.

If you hear a hiss, you've hit the nail on its head.

A long as it wasn't URO brand air, I guess you're ok.

shadetree77 · #14 04-02-2013, 10:15 PM

unrelated, but whilst checking the exhaust make sure all the rubber donut hangers are there. i forgot to check mine when i bought the W116 and a few weeks later the entire exhaust dropped while in rush-hour traffic. it only had one 30 year old donut holding up the whole thing

Marrs · #15 08-28-2013, 12:45 PM

So I'm coming back to this with no result on the chirping/slurping/bubbling sound tho I did get my linkage sorted a bit better. To add one more piece of info, the chirping now only happens when the pedal is pressed down that first 1/4 inch before the pressure of the return spring starts to be noticeable and again in this same portion of travel when I let off the pedal just before it meets the rest position again. I press the pedal and "flutter/chirp" then no sound while accelerating or full floor, or while letting off but when I'm just about to take my foot off the pedal there it is again. I also realized I have a slight bit of play in the pedal that I can't match up under the hood as part of the linkage, where could it be sloppy at the pedal? I don't see how this could cause the sound but anything is possible.

Is there a vacuum line I'm overlooking? You can hear this outside the car too, I notice the reverb when I'm between two buildings so it is not contained to inside the car, could still be trans related as earlier mentioned, just tossing this all up in the air in hopes of getting it sorted. Last resort... pay a pro to do this for me.