Alternator bad?

[Iforgetalot]

1999 540i 6spd

I think I posted this in the wrong place to begin with so I’m posting it again here. Sorry for any inconvenience guys.

1999 540i 6spd

I noticed some noise coming from the belt/alternator area. Like a whining noise I drove around the block while troubleshooting and I smelled burning rubber so I drove back home. As soon as I got on my driveway it let out a horrible noise and vibration so I immediately shut it down. I think the alternator actually locked up or nearly did and the belt was just running over the pulley overheating and giving up a burnt rubber smell.

I started taking things out and checking anything and everything having to do with the belt. When I spin the alternator by hand it has a gritty feeling to it. Is it normal or should it hand spin smooth, nice and easy.

I think I’m pretty much done with the prognosis. I just want to know if anyone has any advice or things to look for when replacing an alternator. You know, the “while I’m at it...” of things.

Thanks guys and gals.

[edjack]

Consider replacing the idler wheels, or at least repacking the bearings.

Replace the belts.

Some have been burned by rebuilds. I don't have a recommendation.

A few have actually rebuilt their existing alt. The bearings are standard. Get name brand bearings; eschew Chinese off-brands, which are often offered in rebuild kits.

The regulator is replaceable.

[ndz]

Do cluster test #9 to check your Alternator charging voltage. You can also check with a multimeter at the battery when the car is on.

Rebuilds.... yep. I just yesterday replaced my Bosch rebuilt Alt from FCP Euro. It was under a year, so I'm sending it back for warranty return today. The voltage regulator inside the water cooled alternator fails.

It's not a terrible job, but I don't want to do it annually any more. Get the fan clutch wrench and holder tools.

[Iforgetalot]

Didn't do #9 test cause it turned into a horrendous noise and I felt the vibration all the way in the shifter, not a good feeling I tell you!

I removed both belts and all idler wheels spin without resistance so I’m getting new ones.

Started the car w/out belt and pulleys and man, it was so quiet. Don’t know about them rebuilt units. Looking into a new one but they are pricey.

[CPHES]

http://www.meeknet.co.uk/E38/Alterna...eplacement.htm - Alternator should spin smoothly. I got known good used ones to keep as spares. Timm knows his stuff. Even if it is not exactly your case, it's good reading. Also check the PS pump and mounts. that has also been showing up as an issue.

[crazy4trains]

Don't mess with rebuilds. I've had to change out multiple rebuilds prematurely. Go for new.

[JimLev]

If you decide to replace the bearings be very careful with the plastic collar that the rear bearing inserts into. It's very fragile.
Like CPHES said it should spin very smoothly. Check the 2 mounting tabs on the PS pump, sometimes when the alt starts to seize the belt will put so much force on the PS pump the mounting tabs can break.

Here's a rebuild kit that has more than you need.
https://www.ebay.com/itm/ALTERNATOR-...R/300919890994

[Iforgetalot]

I may try the rebuild kit. Looks like a fun little task. Car is not a dd and I have a lot of free corona time.

But one more thing. When I spin the alternator by hand it just feels as if the rotor and stator are slightly making contact almost like there is something rubbing inside the unit. I don’t have much experience with anything like this so it could very well be bad bearings and I just don't know what I’m looking/feeling at.

Thanks

[JimLev]

The bearings will keep the armature centered and spin freely if they are good. I've got some pics of some I've rebuilt.
I'll dig them up later.

[Iforgetalot]

Good to know, thanks. Found this rebuild video on YouTube.

https://youtu.be/2_qkAjX5vBI

[CSMBlack-540i]

I may try the rebuild kit. Looks like a fun little task. Car is not a dd and I have a lot of free corona time.

Thanks

Would be nice if you would document the rebuild to pay it forward to future members....

[JimLev]

I used sockets and a dead blow hammer to remove the front bearing.
To remove the rear I used a puller that I ground the fingers down to fit under the bearing. Got it at one of the chain autoparts store.

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[TiesTorN]

well... as I have written in another topic;

"you guys don't need to buy a new alternator, doing that is a complete waste. our water cooled alternators are brushless and they are everlasting when properly maintained. only the voltage regulator, the bearings inside and the white plastic collar needs to be replaced when it shows the symptoms of going out."

and to add to that; if it stops working completely without any reason (if it's mechanically ok) the diode plate could be blown. just replace it and carry on.

[edjack]

Not exactly "brushless." There are slip rings on the armature that excite the rotor to provide the magnetic field. The "brushes" on the regulator contact the slip rings.

[TiesTorN]

there was nothing contacting anything, except for the coil contacting bearings and the collar. I've rebuilt the alt myself and seen nothing like that. but, considering I may be wrong, can you show me the contacting points on a picture?

[JimLev]

Ed, no slip rings on the watercooled alternator, the air cooled does have slip rings.

[Iforgetalot]

Bad news guys. The alternator is toast, Burnt! As soon as I opened it I noticed what appeared to be signs of coolant or something seeping into the alternator case. I believe I found my, very small, mystery coolant loss.

The carnage!
IMG_6393.jpg

IMG_6394.jpg

IMG_6398.jpg

[CSMBlack-540i]

Looks alot like the condition Jim's was when his went out as posted here:

https://www.bimmerfest.com/forums/sh...29&postcount=7

Might still be rebuildable if Jim was able to...

[JimLev]

I'm surprised you found that old post.
Mine was junk, I ended up buying one from the dealer $$$$ as I had a trip planned, didn't have a reliable beater car at the time.

[Mike WW]

Ed, no slip rings on the watercooled alternator, the air cooled does have slip rings.

I understand electricity pretty well, and a conventional slip ring alternator, but how does it work without slip rings? Simple version.

[Iforgetalot]

Might still be rebuildable if Jim was able to...

Jim is the man then... I’m not even going to try. I don’t believe it’s rebuildable. Maybe the pictures are not clear enough but it’s pretty bad. Some of the copper winding is even missing or deformed. The stator and the rotor made contact and there’s corrosion everywhere.

[JimLev]

I understand electricity pretty well, and a conventional slip ring alternator, but how does it work without slip rings? Simple version.

OK, simple.
You either have a coil of wire moving (slip rings required) and a fixed magnet or fixed coils and a moving magnet (no slip rings required).