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Old 11-20-2016, 12:35 PM
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semcoinc semcoinc is offline
Join Date: Dec 2014
Location: Dallas, TX
Posts: 829
semcoinc is on a distinguished road
This is a great pictorial DIY:thumb up:. Props to the OP (yes, he missed the ground cable first removal, but IMHO, a minor transgression ).

My OE alternator failed in the most incredible way possible. It SEIZED completely ! In my entire lifetime of driving I have never experienced a completely seized alternator. Especially not one that gave any hint of shaft bearing issue noises.

My 2003/4.4 had about 92K miles on it.

After a short drive up to my local shopping center, I shut down and went in to shop. When I came out to try to start it, it would crank a very little and then dead stop. I thought that since my battery was an 7 year old factory battery, that I had a battery problem, so I walked to the nearby Walmart and bought a booster.

I attached the booster and then began to crank. It cranked and started then a moment later, smoke began coming from under the hood. I immediately shut down and wished that I had mounted a fire extinguisher in the vehicle (like I had in my other Bimmers), but no joy. I then looked inside the engine bay expecting there to be some sort of electrical fire going and my X going to be a char ball. When the smoke cleared I was able to see that the main serpentine belt had completely shredded and wrapped itself all over everything.

After unravelling the belt I attempted another start and the engine started normally and I was able to muscle the X the 6 miles home without P/S and get it into the garage with just a smudge over half on the temp gauge.

This is where I discovered that the alternator shaft was completely seized and seized so well that the serpentine belt tension was able to prevent the starter from cranking over the engine.

I took the alternator replacement as an opportunity to change ALL the original cooling system hoses all the way to the firewall as well as the heater control valve, water pump, thermostat, belt tensioners and belts.

If you have the budget available, this is a great time to tackle those other items as well.

I was thankful this failure happened near home and not on a far away road trip.

Next on my high mileage components list is the battery, fuel pump and plug coils.

PS: I have used a trickle charging battery maintainer on this X for the nearly 3 years that I have owned it and the 7 year old BMW OE battery continues to do well.

Be careful out there with high mileage components.


Dallas, TX & Appleton, WI
2003 E53 4.4i Pearl Beige
2003 E46 330Xi Monaco Blue
2007 E90 335Xi Black Sapphire Metallic
2011 F25 X3 28i Black Sapphire Metallic

Last edited by semcoinc; 11-20-2016 at 12:58 PM.
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