quote:
Originally posted by Larry Delor:
George,
I have a question...You wrote that the dealer said that most likely your airpump was bad. How did he come to that conclusion?
Did you talk to him/her on the phone, or did you go to the dealership? I certainly am not a professional Benz mechanic, but the O2 sensor (was) would have been the first item that I would have examined with a critical eye,...NOT the airpump.
While I am ranting just a little...airpumps usually last a helluva lot longer than O2 sensors. (what I mean is that had I been the service advisor I might have suggested the sensor be replaced...hopefully the next thing that would have happened is that the tech involved in replacing would have noticed the harness being off and said so)
sorry...just venting I guess 
Larry,
Heres what happened
The oil change was due and the engine was a bit too noisy, so I took the car to the dealership to get the oil changed and check out the engine noise. They called me up to tell me that my belts needed changing and they are causing the noise. They went ahead and did the work to the tune of $300 if I remember correctly. I went after hours to pick-up the car, they had a note on the bill saying they found out after they had changed the belts that the noise is coming from the air pump and it needs to be changed. My first reaction was to question whether they really had to change the belts in the first place. Meanwhile since I picked up the car, I started to have the surge problems when I first start the car, the acceleration was down but I had not noticed the low mileage per gallon then yet. In my mind, I attributed these problems to their diagnosis that the air pump is bad
but was curious about the timing of these problems showing up just after I picked up the car
( On a side note: they had told me as well that I needed to change the tires
a day later the rear right tire blew. When I took the car to a tire shop to replace it, I asked why would a tire rupture as if someone took a knife and separated the side wall from the road wall
he checked the tires to see if they can find anything inside, came back and said they did not find anything, but this kind of a rupture is consistent with having driven on a tire with low pressure for a very long long time
mind you that part of changing the oil at the dealership is to check and adjust the tire pressure!)
Back to the air pump, I stopped by the dealership a couple of days later to pick a key chain or something, and talked to my service manager and the technician who worked on the car at the time to ask about the surge and acceleration problems I was having. The technician remembered the work and said the air pump was noisy and it needs to be changed
and they did not bother to check the oxygen sensor because they believe the air pump is bad. So, I asked them how much was the repair for the air pump, if this will fixe the noise problem, and if they are sure the pump is damaged, etc.
he gave me a total estimate of around $850. Given that I was not convinced they had to change the belts the first time around, and given the amount of money involved, I decided to get a second opinion and I found this web site and the rest is history
My guess is that they disconnected the cable to do some tests and forgot to connect it back
or if you were a bit less naοve, they were looking to fill their service pipeline
I hope this answers some of your questions and once a again, thanks for the suggestion to look at the harness
you helped a lot!
Regards,
George.