This morning when I start my car, after about 1 min, I heard a weird buzz sound from front of the car which I never heard it before. I said, damn....what's now. Then I thought it might goes away once the car warms up. Well, it didn't.
I proceed to drive to work without coming down and check thinking maybe my supercharge is acting up. After I got to work and park my car, I kept the engine running and pop the hood to see where the sound came from...it's the black unit right behind the passenger side headlight and right before the coolant tank. It looks like some kind of pump...the sound is very loud, more like airplane is taking off. The weir-est thing is when I turn off the engine, the sound persist! This is definably no good. I basically need to take the car to dealer right now otherwise the car will either caught on fire when the pump blows up or juice out the battery.
Thanks goodness that there is a MB dealer only 2 blocks away from my work (not my dealer and a bad dealer rated by some members here) and hoping they will take care of it without appointment. They did take the car and service advisor and technician had no idea, at the time, what is going on...why the pump keep running after the engine shut off. After all the write up and when I pick up my stuffs from the car, the pump went off...I thought the pump had finally turn off by itself?! Well, later that day I asked the service adviser, he said the pump is smoked. That's why it stop. Gee....if it caught on fire and burnd my whole car when I parked my car in my garage, is MB going to give me a new car??
Anyway, they later found the problem that my air-pump relay is not shutting off and they have to wait for the part tomorrow. They had already replace the air-pump. He said the air-pump is for the engine air mixture @#@$...it just doesn't make sense to me. But well...hopefully the parts will be here tomorrow and I can have my car back. They give me a Dodge Neon as a loaner...such a turtle.

 

dang, that sucks. let us know how it goes. hope everything turns out well.

 

I had the same thing happen on Friday night. A MB service tech came to my house and disconnected the pump . He said it was the air pump to preheat the cat converters at start-up. He stated to bring it in, but other than not being able to pass emissions, it shouldn't be detremental to drive. When I opened my hood, the pump was already smoking. I didn't want the car to catch fire and burn the house down so I pulled it onto the driveway until the tech arrived.

 

Just got my car back during lunch hour. They replaced Relay and air pump. Everything is under warranty repair. I kind of check out how much they going to charge me if I pay...about 800 biggies! The pump alone is almost $600.
Anyway, got my car back and they washed my car too even-though is a bit drizzle today....nice clean front rim. :P
I'm happy again.

ps. when I leave I bump into one of my co-worker to pick up her car. She also brought in her CLK for service yesterday due to in-accurate gas tank reading...
Also my boss is going to bring in his CLK for service for some suspension problem soon...
MB's QC is pretty bad....

 

Ressurection of the old Smog Pump Thread:
Thanks to the posts here, I knew what to expect.

A month ago at Service B, I asked my SA if she wanted to replace the smog pump relay before it takes out the smog pump, (thereby saving MB some $600). She replied that MB couldn't replace anything before it fails, so no. I replied, "well it is your money not mine".

This AM, I first noticed a slight smell that is not going away, something running very hot. Also my son says "what is that?" referring to a faint but solid motor-like hum from the engine bay, that was out of place. Turning off the car didn't stop the motor. Pop the hood and it is easy to locate, right behind the passenger headlamp. The electrical connector is on the lower end of it, but reachable. I disconnected the pump and probably saved the motor, but it was pretty hot.

Maybe now MB will replace the relay. Oh boy! another visit to the dealer, and more lip from my lexus-owning wife.

 

sigh... problems after problems.... hopefully MBUSA will hear us and try to improve somehow. :o

Jerry

 

what if you just unplug it for good and plug it in for smog?

 

If you did this before the weak relay fries itself, you could probably get away with it. But the cats might get loaded over time. Since the cats are very expensive, I dont think it is worth the risk.

Actually the pump is all electrical and only runs for a few seconds so I presume that there is no performance hit to this design. Just a weak relay that the dealer will pay for. So I am going in for a relay, at my leisure though.

 

Well I ran around town today with the disconnected pump, and this evening I see I have a CEL (Check Engine Light). It is surely caused by the faulty relay or disconnected pump.

So... my guess about being able to run like this, is wrong, needs repair pretty much right away. Unless you like a CEL on your dash.

 

thanks for the info rrf.

 

I am glad I'm not the only one here has the problem........cough cough...I meant I'm sorry that MB QC is not doing it's job.
Just bought another car for the family, my first Japanese car, a Sienna XLE LTD. Man, I do enjoy this car very much. :P I think the QC on Toyota should be better.
The touch screen DVD Navi really amazed me. It even come with backup camera and backup and front park sensors. It works its wonder really well.

 

Got the car back from service (nearly a whole day).
The readout on the CEL was:
P2003 "malfunctoin of secondary air injection code current"

They replaced relay p/n 002-542-26-19.
My pump disconnect was quick enough to save the pump itself.

Since this is a common problem, and many can expect to have it, it MAY be worthwhile carrying a spare relay in your glove box. Even if you don't use it soon, it may save you a few hundred dollars after your warranty expires. It will surely save you a day of hassle. I don't know the relay's part cost, guess is $20.

 

Anyone have a picture of the pump and connections. Is the relay in the fuse box?

Don

 

Many people who own this car have experienced the old air pump issue. More so for those in the early production... cars built and delivered by Dec 01. I started having the problems about 18 months ago and since it was resolved, I have not had it again. This was at about 13k. I have 21k now and the car runs great.

 

The pump is easy to see directly behind the passenger headlamp.
Looks like a large plastic motor with a couple of air hoses connected. (Electrical connection is on the lower section, but is reachable).

All I know is I am sure the relay is in the fuse box area somewhere. The service guy left a lock-down loose for the large rain cover over the fuse area (this is in the engine bay directly in font of the driver).

I agree, pretty sure that the new relay will actually solve the problem. But just to be sure, I will probably buy a spare relay , and then I will be able to tell you exactly where it goes.

 

Picture? how about 1000 words instead.

The relay is located in the engine bay drivers fuse area as suspected.

The replacement (if there) is obvious because it "looks different" from all the others: (Clunkier looking, larger than most and its gray, located towards the firewall).
p/n 002 542 26 19 is printed on it.

You may want to check to see if you have it already, if not.... well good luck.