Ian Dodd
04-05-2005, 10:18 AM
I’ve done a search on the forum and read all the previous threads that seem similar to my situation, but I thought I’d go ahead and post to see if I might get some new insights. Here’s the history:
Not long after I bought the ‘95 525i in the fall of 2003 I started getting a buzzing noise, like an electric toothbrush, coming from the rear of the car at idle. After a good long run on the freeway it would disappear until start up the next morning. Indy BMW mechanic said I was about to lose the fuel pump so he replaced it and the fuel filter. Silence reigned for a few weeks but then the noise reappeared. Now the mechanic said it was the O2 sensor not kicking in for a long time (to explain why the noise disappeared after a time). My wife was driving the car one day when the check engine light came on; she drove it straight to her mechanic (indy, not a BMW specialist, but a good guy) who diagnosed a bad O2 sensor and replaced it. Warning light went away but the noise remained.
Fast forward several months. The persistent noise is starting to make me paranoid so I take it back to BMW mechanic. He claims he can’t hear a thing so I figure years of SCCA racing have damaged his hearing! I take it over to my wife’s guy and leave it with him for a few days. He hears it but can’t seem to get rid of it. I ask him to replace the fuel filter just for good measure, which he does. He tells me this is probably normal and not to worry about it. I pick up the car last night and it behaves perfectly all the way home.
The acid test comes this morning at start up. Sure enough, at the first stop sign the fuel pump starts singing like a robin in the spring. So, do I live with the noise until total silence ensues (i.e., pump failure)? Or do I figure I got a pump with a bad bearing when I replaced it and bite the bullet for another one? Or is there another possible cause of the noise that I'll have to track down like Osama bin Laden (and hope I have more success)
All level-headed advice gratefully accepted. Thanks.
Ian
Not long after I bought the ‘95 525i in the fall of 2003 I started getting a buzzing noise, like an electric toothbrush, coming from the rear of the car at idle. After a good long run on the freeway it would disappear until start up the next morning. Indy BMW mechanic said I was about to lose the fuel pump so he replaced it and the fuel filter. Silence reigned for a few weeks but then the noise reappeared. Now the mechanic said it was the O2 sensor not kicking in for a long time (to explain why the noise disappeared after a time). My wife was driving the car one day when the check engine light came on; she drove it straight to her mechanic (indy, not a BMW specialist, but a good guy) who diagnosed a bad O2 sensor and replaced it. Warning light went away but the noise remained.
Fast forward several months. The persistent noise is starting to make me paranoid so I take it back to BMW mechanic. He claims he can’t hear a thing so I figure years of SCCA racing have damaged his hearing! I take it over to my wife’s guy and leave it with him for a few days. He hears it but can’t seem to get rid of it. I ask him to replace the fuel filter just for good measure, which he does. He tells me this is probably normal and not to worry about it. I pick up the car last night and it behaves perfectly all the way home.
The acid test comes this morning at start up. Sure enough, at the first stop sign the fuel pump starts singing like a robin in the spring. So, do I live with the noise until total silence ensues (i.e., pump failure)? Or do I figure I got a pump with a bad bearing when I replaced it and bite the bullet for another one? Or is there another possible cause of the noise that I'll have to track down like Osama bin Laden (and hope I have more success)
All level-headed advice gratefully accepted. Thanks.
Ian