OK - it just got more interesting. When I got home last night, I scannned it with my OBDII reader and it had no codes, and no codes pending. Backed it into the garage at about 10:30, and heard a slight squealing noise. It was late, so I wrote it off as needing a new belt, and went to bed. This morning my wife drove it to the gym to work out, and called on her way to tell me that it was making a "funny grinding noise". She said there were no messages or warning lights on the dash, so I told her to just ignore it. She then called to tell me that it was still making the noise, only now "it smelled funny". She couldn't describe the smell. so I told her to call me again if it broke down. She called back in about two minutes... siad that it made a loud squealing noise, and died. She tried to restart it while I was on the phone with her, and it made a loud squeal when she cranked it. So now, it's hitched to the back of a tow truck, headed for my house.

I'm thinking that it sounds like one of the accesories on the front of the motor has seized up. Anyone have other opinions?

Chain Guides?

would they squeal like that?

They can make all sorts of noise because the chain is slamming around in the case. I mean a squeal to your wife, you and me are all different. Squeal to me is when a belt is slipping. Squeal to someone else is when there is high pitched metal to metal contact. Hopefully a pulley or tensioner seized and can be a good fix.

hopefully it is not the chain/chain guide
or ur in for a fattty bill

or 2-3 days of DIY

Well, I actually heard the noise over the phone when she tried to crank it, and it didn't sound like metal on metal. If it is the guides, I can fix it. It's our third car anyway, so it's not a big deal if it's down for a few days. The noise it made last night definately sounded like a belt squeal, so I'm hopeful that it's just a tensioner or something simple like that. She sent me a pic of it being loaded on the tow truck, and there was no fluid under it, so that rules out a water pump explosion. This is my third BMW, and the other two have had idler pulley issues, so I expected this one to do the same sooner or later. BTW - the X5 has 109,000 miles on it.

wow, ok let us know what it is.

Pull the belts off, and try to spin the pulleys by hand.

I will.

I just found a thread on another forum from a google search where a guy with a 740i experienced almost the exact same thing - he had a seized alternator. I'm hoping for a simple fix like that. I can pull the alternator and rebuild it pretty cheap. Just put new bearings in my M5 alternator a couple of months ago. Cost $21 - much cheaper than a $400 rebuilt unit!

Yeah, lets hope its a seized alternator. If I had the time to tinker, I would have pulled my alt off and checked to see if it was a voltage reg. $60 and a new reg sounded pretty good. But I just said, eh F*ck it. Its got 91k on the clock, WTH, time to change it. SO I spend 4 bills on a rebuild bosch unit.

Yeah - i just checked several auto parts stores, and $412 was the cheapest I could find. I'll tear into it tonight and see whats up.