sanf

Whenever I come to a complete stop (red light, stop sign..etc.) While stepping on the brake, I hear random knocking sounds coming from the rear right section...sounds like its coming from the fuel tank/pump.

Car: 2007 C230, Auto

anyone else has the same issue?

Thanks,
Sanson

ZAKON

Check your back brake pipes. (!)

sanf

hmm...what should i be looking for? the pipe touching anything or ???

anthuny85

mine does this too...i wondered this today and its funny you posted this thread lol, if you figure out what it is lemme know.

sanf

somewhere I read that it has to do with the fuel kicking back while you are stopped? but for whatever it is... it shouldn't be making sound like that. haha.. either a bad design or something's wrong.

MCONDE01

Thats funny because my car does the same thing at times...always thought it was the rear brakes just pumping...

Hope it is not something real bad????

sanf

since not too many ppl are having our problems. I guess there must be something wrong with our rides. I have an appointment at the dealer an hour from now. I will ask the dealer what this is all about.

BIGjohnny

Had this problem on my E Class W210 and C Class W203. E Class had a defected catalytic converter after 40k miles. C Class resonator (Brabus) was loose due to a broken screw. Have the dealer check it, free anyways unless you're warranty is out. Good luck.

TA-9FF

Mine does that too. AND I have a nice "shrill" sound to go with it too.

Went to the dealership to have it checked out a few months ago, dealership said the exhaust is working under FULL MB specs, and INSISTS they tested my car with 5 different other C-Classes.

So enjoy the annoying soundtrack.

Complementary of Mercedes-Benz.

I think I might actually go to the dark side and trade in for a Z4 M Roadster in a few months....

shahedC

Eddie Murphy might be stuffing bananas into it...

shanetoast

It does have something to do with the fule. We have already talked about this before in another Thread. I forget what it was called but its out there. And in that thread someone tells us exactly what it is. Im almost positive that every C class has that problem. Damn peices of sh**.

sanf

I got to the dealer at 530pm. We were about to go for a test drive then the service consultant came back from talking to the service manager and told me that there is actually an service bulletin by Mercedes regarding "knocking sound around the fuel tank area".

They gave me a C280 4matic to take home for the night. My car should be ready sometime tomorrow, I've asked them to make me a copy of what they are going to replace. Hopefully they will have one ready so I can list out the exact problems to you guys.

sanf

update: after leaving the car there for 2 days last week, the story has changed. They couldn't find out what the problem is. However, they have ordered a "special" valve for the fuel pump section and confirming that's where the sound is coming from (by Mercedes bulletin anyway).

I picked up the car last week after being "inspected", the first 10 min of driving was pretty ridiculous. The idle would jump between 500 to 1k, the whole car was shaking and felt like it wanted to stall. I guess the car's computer was trying to learn everything again, it was fine later.

So today, 6 days later. The check engine light comes on. I dropped the car at the dealer for the "special" valve install and hopefully they can tell me what the problem is with the check engine light. I hope they are not just messing with my ride so I can go in for more services. I kinda hinted and they acknowledged.

04mbc230

Bump.. Any updates on what this problem is? I have this and it gets louder as time goes by.


I am also thinking it's related to the fuel pump. Anyone fixed this and had a pin point confirmation of this sound?

pcy

I have heard that noise on my '07 C280. I hear that noise [more pronounced] when I am parking the car in the garage - it's like a knock/rattle. I am 100% sure it is not any of the exhaust/related components because I've investigated this in the past. Last week, I removed the rear wheel well liner and looked under there for fuel evaparation system. Everything looked perfect. Nothing loose there. I am aware there is a valve and a bracket installed. They are in perfect condition. I took pictures of all related components.

The next day, as I was pulling in to the garage, I heard the noise louder (tank was less than quarter full), so, I left the engine running and removed the rear seat and removed both panels on both sides on fuel tank. When I put my hand on the fuel pump, I can feel the noise is coming from the fuel pump. I kept the engine running and removed the fuel filler cap, I can hear the noise definitely coming from inside the tank.

I ordered new fuel pump and the filter (both sides). They should arrive this week. I will install them during the Christmas break.

MBC230/996

I hear the same sound. Can you report back if that fixes the problem?
Are you assuming that the pump is on it's way out?

pcy

Whether the pump is on it's way out or not, that sound is not normal. And, I don't want to take chance with fuel pump.

Given my car has 98K miles, I think it's prudent to go ahead and replace the fuel pump and filter.

Yes, I will report back after I change the pump.

Michael_dav

hello guys
any news? did anyone fix it ?

Michael_dav

hello guys
any news? did anyone fix it ?

pcy

I replaced the fuel pump and filter, the noise is still there.

I wanted to change the fuel pump and filter as a preventive maintenance; I was certain the noise was coming from inside the tank.

wvadam

is it possible for you to post a recording of the sound?