DIY: Bosch 150amp Alternator Repair - V8 Water Cooled Unit

[Braymond141]

Well, my alternator died on me an hour away from home last week. I had to buy a second battery, and drove home. Made it half way, then swapped in the other battery. Barely made it home, no lights, cluster lit up like a tree, and transmission in fail safe. Was 9pm, snowing, and the cluster read 6.5volts

Truck has 53k miles on it and is a 2001 4.4i Sport.

I bought a replacement alternator, but wasn't content with having a dead one laying around or pawning it off as a core. I put the replacement in my truck and then spent a good evening scouring for a replacement regulator for the bad one (my formulated opinion on what had failed). I finally found one, and it arrived today

It's only cost me 65 dollars to fix my alternator, but mine just had a failed regulator.

Please do not ask me what's wrong with your alternator.
Please do not ask me how to test the alternator.

I stay very busy with work. I'm not here to hold your hand, you either understand what's going in the pictures or you don't. I'm sorry for being so blunt, but I used to have many guides up. It turned into a huge hassle so I took them all down. The only reason I'm putting this up is because I empathize with those of you who get stuck in the water because your alternator just failed. The repaired units can be big money too (depending on where you go).

The replacement part can be found here in California from an eBay member in the LA area.

Her ebay ID is: suppersellstore
The item I purchased is:[Water Cooled Alternator regulator Mercedes 01 02 Europe : eBay Motors (item 220509375691 end time Apr-10-10 22:32:00 PDT)
The keyword(s) search is: Bosch 0-122-9AA-0X0
Bosch 0-122-0AA-0B0, -0D0, -0R0, -1A0, -2A0;
Mercedes 000-150-05-50, 000-150-06-50, 000-150-20-50, 000-150-28-50, 137-150-09-50

Onto the pictures.

Removing top casing. Pry off once you remove these screws and one nut.


Remove Regulator - Take note of the wire positions
Reinstall new Regulator


Clean lid channel


Clean lid


Reinstall Bearing cover


Reinstall Lid Oring


Reverse install - Silicone edges -Done

Bearing specs for those you want to rebuild more in-depth


Kragen, Napa, Autozone can't test this alternator, so I had to rig up my own test. I used our 540i to demonstrate the alternator working again.

Power was disconnected from the cars alternator and then jumped to the rebuilt alternator.
Grounds were jumped as well.
Regulator plug was removed from installed alternator and snapped into rebuilt one.
Drill with socket attachment was used to spin the alternator.

I could not get the voltage to go higher because the drill is not fast enough. The alternator when installed spins a lot faster than the engine rpm.

YouTube - X5/540 V8 Water Cooler Alternator Test