Hey Lads / Lasses
So, this has already been corrected with a nice, new 200amp alternator and belt but I wanted to post this here as a caution and also as a curiosity?
Happened about 2 weeks ago - I had just left my place and got only about half a mile down the road. I had noticed a couple of days prior that a whine had suddenly started under the hood. Given the fact that the alternator was the same one I received when I bought the car, it was high probability that the ole boy was packing it in. I had only driven the car a total of about 10 miles with the whine under the hood and then on that day 2 weeks ago, it threw up.
So here are a few key elements when this happened:
- The first thing that popped up on the dash was the warning that the "battery was not charging". Figured as much
- Not long after that, a variety of dash warnings popped up including DSC failure, ABS and I believe another one or two, but I wasn't keeping track at the time as I was stopped at a stoplight and smoke started wisping out from under the bonnet. Had other things on my mind.
- Pulled into a gas station to look under the hood and since I was only half a mile away, decided to flip the car around and quickly make it back to avoid having to be towed. At this juncture is where things got weird and the reason for the post.
- The car started to ping like crazy under acceleration! This is what I am trying to understand from the group. The car was still running although I was getting these dash warnings. When I would get more up to speed, the dash warnings would disappear and then come back on again as soon as I slowed. Guess this makes sense, but I don't understand the pinging.
- I did manage to get back safe and sound and popped the hood to let the remaining smoke escape. Ordered the new alternator and a new serpentine belt and went to work replacing it. Since I have a cold air intake and my car is NA, I didn't have anything complicated to remove to swap the alternator. The only thing that was a little bit of work was pushing the bushing back through the alternator bracket to accept the new alternator.
- The serpentine belt was another story. What a pile of **** that design is. I had to bleed the coolant out (not all but about a gallon to be sure), This allowed me to remove the upper radiator hose so that the fans - yes, the fans could be removed from the car. Several wiring connectors, zip ties and lots of fiddling around, I finally got the fans out which, BTW, is just to give you the extra precious few centimeters to get the tensioner bracket far enough away from the front of the engine to slip the belt out from behind the tensioner. The tensioner is held on with a 13mm bolt and there isn't even enough space to get a normal wrench down there. At least not any of the wrenches I own - and I own quite a variety. Once all was replaced, car fired right up, and I swear it runs better now than it did previously. Wondering if the old alternator was lagging from age and maybe impacting the running of the engine somehow? Kinda ties into the other question.

Anyway, to anyone with normally aspirated engines, the alternator won't be a big issue but be prepared to spend much more time getting that stupid belt off. Glad I did as I would expect the belt would have been next to go although it looked great to my eyes. No cracking or fraying at all but it did look melted a bit on the flat side. Probably a function of the belt slipping on the disintegrating alternator. I hope this, and some educated responses, will help others that suddenly lose an alternator in flight.

 

The whine from the alternator will have been magnetic imbalance due to most probably diode failure. All alternator failure modes bring on the warning light sometimes when the ignition is off.
As the device is a 3-phase unit missing or distorted phases produce strange voltage variations in the system hence the computer not being happy.. to move the sleeve in the alternator bracket easily and in about 30 seconds you need a length of threaded rod/a socket and a washer. It's in my post on changing the alternator.

 

When I pulled the failed alternator out of my wife's 2006 XK8 in July 2018 to have it refurbished, I also decided to replace the serpentine belt at the same time (the car had just over 115,000 miles on it). As you indicated, removing the radiator fan assembly made that job considerably easier. My notes from that day show that I drained the coolant reservoir, then pulled the upper radiator hose and pumped out a bit more coolant. At that point the fan assembly could be lifted up and maneuvered out of its bracket. Once it was set aside out of the way, replacing the serpentine belt was indeed a much more accessible job. Putting the hood all the way up into the vertical service position was also required....

 

None of this is required on the basic 4l ...one hand has the 15mm spanner and the other loops the belt.

 

Yeah, but that other .2 of a liter makes all the bullshit so worth it lmao

 

True true true... I have found no reason to go to such lengths to change and alternator,,, belt, remove the fans.

Yes, hood in "service" mode (1min)... With the fans I undo the two mounting bolts, I think remove the upper trans cooler line (30seconds), the two fan plugs, curse, swear, look and scratch head a few times, and wiggle it out.

Alt, remove air box, 15mm socket or breaker on the idler pulley, release tension, move belt most only off of alt, unplug/bolt wiring, front bolt top, then long bolt bottom,,, more cursing swearing and wiggling to get alt out. Then new one back in. Sometimes have to rig something up to drive back that funky spacer (don't know the real name).

I have found no reason to remove the fans to pull the alternator. Less I'm forgetting something...?

 

If you go back to my post 6/11/22 titled "Dead Electric Frying"...... This was exactly same problem!

 

The alternator wouldn't be an issue with the fans in, but the belt certainly was.
The belt has to come out from behind the tensioner on the 03 and newer cars. I think it can easily come off from the front of the tensioner on the older cars. Since there is only about an inch of space between the back of the fan on the left side (where the tensioner bolt is), it isn't possible to release the 13mm bolt enough to allow the tensioner to move forward enough to slip the belt out from behind it. Maybe you could wrestle it out if you really had to but the limitation I met was that I didn't have a tool setup slim enough to fit down there regardless. A standard box-end wrench was too short to get any torque on the bolt as it is pretty far down there and a socket with its wrench doesn't fit at all. Maybe an elongated flat wrench would do it, but I would call that a very specific tool to seek out.