MB Marko

Hey all In the past week or so when i start the car up when its cold it makes some weird almost computerized noise pretty loud for about 30 seconds from the drives side when i tried to record it I couldn't pick it up on my awful phone its almost a buzzing noise any idea what the heck this is? and it only happens when i start my car the first time in a day.
2012 c300 4matic sport

here is the sound

noise #2

Skyline45

Could be the EIS? I always hear it after I turn my car off and sit in it for like 30 seconds. I've never heard it before or while starting my car though. :/

EDIT: Come to think of it, I do hear it before I start my car. Though it's not a buzzing noise, but more of a quick electronic sound. Like it's unlocking something.

MB Marko

well to be honest the noise is more of a vvvvvvv(sound when you sound out v lol) up and down sounds than a buzz if that makes sense LOL i'll try to record it its pissing me off though i have not heard it before now out of nowhere it's doing it

Skyline45

Hmm, if it's just a quick sounds then I would say it's safe to assume that it's your EIS, and it's normal. You may of just never noticed it before now.

MB Marko

hmm ill try and make a video tomorrow morning and post it after work maybe it will help it seems like its coming from under the hood i went out now to start it but it didnt do the noise it seems to happen once a day the first time i start the car

MB Marko

ok it made the noise again ill post a video now once i figure out how to

MB Marko

here is the clip of it hope this gets the problem solved

Skyline45

Ah, yea that's a completely different sound than what I was thinking lol. I would say it sounds more like a vacuum of some kind. Mercedes used to use a lot of vacuum tubs to run components on their older models. I know this from working on my SL, but idk if they still use this tech on new cars.

Sorry I couldn't be much help man :/

MB Marko

no worries hopefully more members help out thanks though

Skyline45

I just thought of something though. Could it bu you AUX fan? It runs on an independent system from the engine's belt. When it spins up, it's very loud and sounds kind of like that. It's the fan that's in front of your radiator.

MB Marko

is it something I should take to the dealership to check out? i have no clue maybe in 30 min or so ill pop the hood open and see what happens when i turn it on. just wondering do other w204 drivers have the same noise?

MB Marko

anyone?

xjmoe83

To me it sounds your secondary air injection pump. It's an electric pump at the front/center of your engine. They sound similar (from what I could hear) to your video. Good luck!

MB Marko

is it a problem i should get checked out? or does everyones sound like that

Skyline45

It wouldn't hurt to get it checked out by an indy shop. Though no, I do not hear this on my car other than the loud AUX fan at times.

MB Marko

well i guess i still have warranty so i might as well go to the dealer but i absolutely hate that they need to keep my car for a day/night

xjmoe83

If it was the sec air injection pump, they would just recommend to replace it. You could just wait and see how it goes. Worst case, it eventual dies and the check engine light comes on, then you replace the pump, fuse and relay.

Skyline45

OH! I just remembered that the W204 had a recall on the power steering pumps for some models. Do you know if this recall was already done on your car? If not, I bet that's what it might be.

EDIT: Nvm, yours is a 2012. I believe they fixed the defect before that year.

MB Marko

hum i made another video ill post it now its getting louder each day

MB Marko

listen to this hell

xjaymzzx

That does not sound good at all, take it to dealer asap

shotgun_banjo

That sounds awful man! Like metal grinding or something. Bring it to the dealer asap.

MB Marko

so i showed them the video its long weekend so one guy was briefly there he said it sounds like the emissions pump is going but its still drivable until i get my appointment warranty better cover it lol

xjmoe83

The air injection pump usually only runs the first 30-90 seconds after a cold startup (unless the relay gets stuck). Is that when this problem occurs? Can you tell if its coming from this motor (in the pic)?

MB Marko

ya it defiantly is coming from the motor i have my appointment Wednesday ill find out 100% what it is then