If the X is only doing it when cold started (overnight or long periods sitting)... it could be normal. Your secondary air pump will run to help heat up the catalytic converters to get it into closed loop faster. Perhaps your secondary air pump is starting to go bad and is making more noise than normal. This is fairly common for your mileage M54.

The secondary air pump is the big circular thing on the passenger side rear of the engine bay. At least that's where it is on E46's... I assume it would be in the same area on the X5 since the exhaust valve (also a common failure causing the pump to go bad) is on that side.

It is easy to find out if it is the secondary air pump. If it is going bad you can feel the vibration by touching the pump right after a cold start. The pump doesn't run long so if the roar stops and the vibration goes away you will know it is a bad pump.

If a shop do accept replacement parts from an owner, the shop does not guarantee the part that was supplied to them. The shop is also under no obligation to remove and reinstall another replacement part without compensation. Perhaps the owner can submit a claim to Pelican parts.

I've always been in the camp that you get what you pay for.

I wouldn't ever have anything done at a shop that allows customers to buy their own parts . A portion of the profit of a shop is the margin of profit of the part cost from wholesale to retail, generally 30-40%.

My reasoning is that if a shop is not making full profit on a job they could be inclined to reduce labor time to help make up the difference. That could mean they would be cutting corners and/or not be as careful or interested in doing the job correctly.

Oh agree with that... and what bcredliner said above. I was not suggesting they R&R the new one for free, nor that they were responsible for warranting the part the first time.

What I was saying is that the shop should have said, "Hey, the alternator you brought us, has a bad bearing. Do you want us to order one of ours at $X.XX, or wait for a replacement from your supplier?" It would have taken almost zero time to diagnose the new alternator as having a bad/noisy bearing.

There will always be lots of ideas here and from outside sources. Some will hit the mark, some will be off the wall and some will be declared as THE cause and are only one of many potential causes. It is never a good idea to buy parts based on any input until troubleshooting verifies that is what is wrong. My suggestion is to stop buying parts and go through the necessary troubleshooting to find your particular cause. Every one of the parts you purchased that didn't resolve your problem could have been easily eliminated as the cause by troubleshooting.

First and foremost----I suspect the problem you have is not a coincidence. Since the whining started after the alternator replacement, the probability is very high it has something to do with that replacement not other part failures. That includes the alternator itself. Was the alternator a new one or rebuilt? Was it a BMW part or original equipment mfg. (OEM)?

I would use an auto stethoscope to listen at different points around the engine to hone in on the source. Obviously, be careful around moving parts but you should be able to place the probe on the alternator. You can also use anything metal or even plastic pipe.

That said, finding no leaks after the MAF does not eliminate the MAF as the cause. The reason I asked about loss of power was because when the MAF is bad or the sensor needs to be cleaned there is often a significant roar and most of the time a loss of power. The engine sounds different at an idle and will roar when you rev the engine. I would check the sensor connection and the wires to it. I would remove the sensor connection and see if the roar goes away. If that doesn't help I would still try cleaning the sensor wires While I just suggested you don't spend any more $$$ until you find the core problem with troubleshooting. I consider cleaning the sensor wires troubleshooting since it is inexpensive and easy to do. I would purchase a can of MAF cleaner and spray the sensor wires liberally to see if that cures the problem. Cleaning the sensor doesn't alway work but the chances are pretty good it will if that is the problem. FYI-replacement of the MAF is recommended as PM about every 60,000 miles.

Sometimes you can find a vacuum leak by spraying starter fluid or brake cleaner on likely locations. If there is a significant vacuum leak the engine RPMs will increase when the spray reaches the location. Quite often a significant vacuum leak can be found by ear. The troubleshooting process to completely eliminate the cause is a vacuum leak is to have a smoke test done.

He fixed the whining problem bcredliner. It was the rebuilt alternator that caused the whining... which made the most sense after all since it only started after it was replaced.

As for troubleshooting... definitely agree with what you said. No reason to throw parts at it until you know what is faulty. Which is why his shop should have told him upon picking up the truck that the new alternator had a whine in the bearing...

Oopsie, I wasn't paying attention and inadvertently responded to post #1. Time to troubleshoot my short term memory again.

maybe its the 2 kids in the backseat ?:D

I've made a video and audio so you guys can hear what I'm hearing. This is in idle in the garage. I let my son step on the gas intermittently so you can hear when it revs. So when you listen to it, and the sound goes up and down, that's my son revving the engine. You can hear it when he steps on it and makes a loud noise.

http://www.en2creative.com/BMW_X5%20-%20Broadband.m4v