Sunday, 10 July 2016

BMW X5 E53 4.4i Alternator Rebuild

BMW X5 4.4i Alternator Rebuild

After successfully rebuilding the 180A Valeo alternator on a BMW E53 4.4i I thought I'd post a rebuild procedure.

Parts needed

  • Bearing o/d:47mm  i/d:17mm  thick:14mm
  • Bearing o/d:35mm  i/d:15mm  thick:11mm
  • Regulator (BMW 12318510090)


  • 1/2 inch drive, long T50 torx male
  • 24mm socket, modified to allow external spanner (see pics below)
  • ThreeBond 1207B sealant
  • Long 16mm socket (e.g. spark plug socket) for installing small bearing.
  • Bearing puller


Removing the fan cowl is essential.  Removing the radiator is not strictly necessary, but it makes the job of getting the alternator out much easier and avoids accidentally damaging the radiator.  I removed the radiator :-)


There are 2 bearings a large and a small one.

The small bearing is pressed onto the rotor shaft using the 16mm spark plug socket.

There's not a lot of clearance below the small bearing, which necessitated the purchase of new bearing puller tool.  Cool!

The larger bearing presented a separate problem.  The rotor should slide into the large bearing - but it was stuck in the old bearing on this unit.  The retaining plate was completely destroyed when I pressed out the rotor from the case.

This was a perfect opportunity to have another play with Fusion 360.  Here's the replacement plate I decided to fabricate:

I have shared my Fusion 360 design and you are free to use it:
Please ping me (for karma) if you fabricate my design.

Here's the fabricated plate installed with the new bearing in place.

 Before re-assembly clean out the old black/grey sealant from both sides.

I used ThreeBond 1207B that I had in my toolbox (from the time I rebuilt the intake manifold system on this same car)

Apply the ThreeBond sealant to both halves.

Note the rubber seal (3mm x 1mm cross-section) just below the windings.

Excess sealant after screwing the casing back together.  I removed the excess with a rubber spatula then cleaned up with acetone.

Install new regulator assembly (no pics of this unfortunately).

This is the 24mm nut that retains the pully. 
A modified 24mm 1/2 inch socket is required so a spanner can be used while a long T50 torx stops the shaft from rotating.

Thanks for reading.

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