E53 Alternator DIY

[ddjames]

The battery light of my '03 X5 (97K miles) came on last night on the way home from work. I pulled out the multimeter tonight and took the following measurements:

No load (battery disconnected): 11.77v
Engine off: 11.54v
Engine idling: 10.96v

The battery was replaced about 13 mo. ago and the belt (what I can see of it) looks to be in good condition. Other posts on this forum lead me to believe that it may be time to replace the alternator.

If anyone has a few minutes to answer some questions I'd really appreciate it!

Anyone know of a DIY for replacing the alternator? (BTW, Hayaku's DIY for CV boots by was fantastic!)

The alternator is barely viewable from the top of the engine. Is there no way to replace it from the bottom? Dropping the splash guard doesn't provide any usable access?

RealOEM lists several different units (90A / 120A / 140A / Bosch / Valeo). For purposes of ordering ahead of time, is there a way to determine which unit is installed prior to pulling it out?

Replacement alternators I've found from searching the web either come with or without pulley. Any pros/cons here?? Is the existing pulley difficult to remove or require special tools?

Any last words of encouragement (other than what's already posted)?

Thanks in advance. Keep up the great work!

~Dave

[EOD Guy]

O-Rileys, bosh rebuild, lifetime warranty. Must be done from the top. see thread from two days ago, same subject

[LI_BIMMER]

Replaced mine earlier this week but I didn't take any pictures. =(

http://www.xoutpost.com/x5-e53-forum/...-x5-3-0-a.html

A couple of points for you. The back of your alternator has the manufacture and amp size. Too bad you can't see it to place your order but I suspect yours should be the same as mine.

Mine was a Bosch 120A alternator and came with the pulley attached. The replacement was identical and I paid $154 (mechanics (father-inlaw) discount) for it locally and it did not include the needed $100 core deposit. I took off the Air filter housing/duct work and took off the two bolts that holds the steering pump resevoir. This allows you to move the resevoir to the side to make way to pull the alternator up. I also took off my fan blade as this allowed me to get some more space with trying to take off the two alternator bolts.

Removing the fan blade may not be necessary but I already have the special tool to hold the fan steady so that I can spin the fan nut off. Some folks can probbaly get away doing this without the tool. The fan nut is reverse thread. I was orginally going to remove the tensioner pulley to but opted to remove the fan blade just to get some more working room.

To save time, make sure you record the travel direction of the fan belt. I had to reference this board for the diagram to confirm it was placed back correctly. I was initially wrong.

There are two connectors on the back of the alternator. One is a clip type and the other is a plastic cover over a nut that holds the red cable. Using a rachet on this is fine. I spent some time on this as I thought the cap pops off the nut but its attached to the bolt as one.

There is also a hose attached to the bottom of the alternator that you can snap off. Be careful when using a screw driver as you may break the plastic on the alternator side when trying to release the hose. Your new/rebuilt alternator should have this anyway so this point may be moot unless you need to take the core back in good condition. =)

Once I disconnected the alternator, I just pulled it out with the pulley side facing up and installed the rebuilt the same way. There is a nut that you may need to adjust on the bottom part of the alternator that prevents you from getting it onto the bracket for mounting. This can be easly hit or punched out slightly. When you mount it back with the bolt, it will pull the nut back in so don't worry. Be careful on hitting the alternator with a hammer directly when trying to hit this nut. Use a screw driver or another tool to punch or push the nut out while tapping it with a hammer.

This may sound like a lot but as you begin the break the X down to get to the alternator, it will make sense. Hope this helps.

[ddjames]

Thanks for the great info! Will probably do the removal tomorrow night and order a replacement after confirming manufacture and amps. Local stores (Advance Auto and AutoZone) want too much $ (almost twice the price of O'Reilly and Bimmerzone) and the units don't come with the pulley.

Do you have any info on a cap nut (12 42 7 565 287)? Some of the units I found on-line specify that the cap nut MUST also be replaced.

Also, is there some place I can find torque values for the mounting bolts? Or should I just follow the German standard: Gut-n-Angespannt (good-n-tight)!

Thanks again!

[EOD Guy]

Mine came with a new nut , and I torqued it to good-n-plenty

[LI_BIMMER]

My replacement came with a regular brass colored nut and it did not have the plastic cap on it. My orginal plastic cap/nut was good so I reused it. If it wasn't, I would have used the nut that came with the remaufactured alternator.

As far as torque, I tightened as much as I could until the bolt stopped turning then I stopped. I don't know what the torque guide lines are but I am bummed out that there is no Bentley manual available for the X. I need a good reference for this. Any ideas?

Also, I sprayed the some penetrating oil on each bolt just so it can turn easily when going back onto the alternator. I guess WD would be fine as well and it will save you some additonal effort as these bolts are very long. Keep in mind that once you can see the thread of the bolt , there is no need to keep turning to get the bolt out. Wiggling it in and out will allow you to remove it.

[EOD Guy]

I used the TIS electronic manual, but still used the good n plenty

[ddjames]

Alrighty now! We have progress! And maybe a question or two.

Air box and intake parts are off, p/s reservoir bolts out, alternator bolts and deflection pulley are out. The alternator bolts were a real &%$#@! given that I didn't remove fan.

Couple more questions if you don't mind.

How do you release the remaining tension on the belt? I thought after the deflector pulley was out there'd be enough slack to slip the belt over the alternator pulley. This doesn't seem to be the case.

When you pulled the alternator out did you push the p/s reservoir towards the back and bring the alternator up between the p/s reservoir and the radiator expansion tank? I'm not quite there yet but it looks like a tight fit. Was wondering if it would be better to disconnect the two hoses from the radiator exp. tank and bring it out sideways and then up?

Did you ever get an answer to your question about disconnecting the battery first?

I noticed the belt has some cracks in it. It's 97K miles old. Do you know how much additional work is involved to replace it at this point?

Really appreciate all the help and tips!

[fast4d]

please disconnect the battery before you do this!

you did not indicate whether this is a I6 or V8 so I can't help you.

[ddjames]

It's an M54 (I6).