My automatic 1999 328I E46 Sedan with 115K miles has developed a problem, the source of which I have not been able to identify. It started about 10K ago and has been slowly getting progressively worse. The sound is a constant low frequency whirring sound that APPEARS to be coming from the rear of the car. It changes in intensity with speed, but not really in frequency, and starts almost from standstill. It does not change at all with anything that I do to the car; turn left or right, brake, accelerate, coast, etc. Thus, I have decided that it is probably not wheel bearings or the diff, though I certainly could be wrong. It is not the tires as they have been changed since the noise started with no effect. If it is the center bearing, am I better off just replacing that or going with a rebuilt driveshaft such as the one from Staked? If anyone can shed some light on this, I'd appreciate it. Thanks, Tom
It would be best to run it on a lift to see if someone can determine the source of the noise. If there is no noise on the lift, then it would be a wheel bearing.
Although when I had a bad center load bearing, it was not noticeable on the lift. But only when the suspension was loaded. And only noticeable in reverse. Don't know how different the E46 is from a E36, but I had the flex disc changed at the same time since the driveshaft needed to be dropped.
Good point about the center bearing, they tend to only make noise when loaded. At least you could rule out other things, though. The E46 is basically the same. The center bearing is difficult to hear on the lift, but they are know for living a long long life. There are still E30s and E28s kicking around with their original bearings (though not many.) I suppose it could be though. If you get it on the lift you can insepect the rubber around it to see if it has sagged. If it has, then it needs replacing anyway. You probably do not need the whole driveshaft, but if you have the scratch, Driveline in Portland or Beyer (who only sell to shops) do great work. It will come with a new bearing installed, IIRC. It is not a big deal for a shop to install a bearing, but if they want to charge more than a couple of hours (on top of actually removing the driveshaft) then it would be worth getting a reman if you can get it cheap enough.
Center bearing is about $35. A driveshaft will cost you about ten times that. The labor will be about the same for either. I'd rather gamble $35 to save $300 than simply spend $350-$400. Any shop that would plan to spend more than 2 hours on this job is probably incompetent.
The labor is not the same, because in addition to having to pull the shaft, you have to take the thing apart, pull the clip, press off the bearing, etc. Some shops overcharge for that, expecially if their hourly is $100 or more. If that is the case, it may make sense to spend the extra bill and get the shaft with a new bearing installed. I didn't say his mechanic wasn't incompetent. It may be the case.
I disagree with replacing the whole drive shaft. If you are up to it DIY replace the bearing. If you must take it to a shop I would at most have the drive shaft balance checked. Replace the Guibo and check the exhaust hangers while you are doing the repair.
