The alternator packed up on my girlfriend's 1.4 MPI last Thursday. I've been trying to source a replacement, but have come across many with similar part numbers. It's a Bosch unit and seems to have been fitted to many vehicles.

I have a few questions. Which is the most likely part to have failed? The brushes are fairly worn, as are the slip rings. Am I better off buying a whole new used unit, or trying to source replacement parts? Lowest cost is my preference.

The part number on the regulator/brush pack is:

F 00M 145 401

Are there other Bosch equivalents with a different part number?

The part numbers on the alternator itself are below. What is the significance of the letter on the end of the first number? I've seen those advertised with the same first 9 numbers, but a different letter.

037 903 025 M

0124 325 013

Thanks for any help you can give.

As its a 90A i presume you dont have A/C, but I would try a local breakers yard.

 

When i had an MPI as my daily a few years ago, the alternator was packing up, it wasnt charging and the bearings were shagged. I just got one for £25 from the breakers yard.

 

 

If you were closer to Medway, i have a spare one you could have for £20. ill double check the part numbers tonight for you.

Thought I'd found you a cheap brushpack on ebay, but then noticed that eBay's search had just found something with a vaguely similar part number, not the right one. Another edit: This one may be OK actually; further down the listing it gives a list of Bosch alternator part numbers that it claims to fit, including the one you quote. At <£15 delivered maybe worth a gamble, but only if you've already checked one or two things below.

 

You say the brushes are worn, but how short have they got? Over 5mm and they probably are still doing their job, unless the sliprings are really worn down. How many miles has the car done?

 

Have you checked and excluded the signal wires (L, DFM) as the cause of your charging trouble? It would be sad to replace the alternator, find yourself with the same problem still and then find a busted wire.

 

Lots of secondhand alternators of the 037903025M part number on ebay at various prices; you could get unlucky and get one with very little life left, but I imagine most scrapped/broken cars still have alternators that are fine, so your chances are pretty good.

Apologies for the lack of response on this, and your help was much appreciated.

I was very busy at work at the time, so didn't have much spare time to get this sorted. I checked the signal wires as you suggested, Wino. All was good there.

I decided to go for an alternator from a scrapyard, and as my local offers them for £42 with a one month warranty, that was ideal. At that price it wasn't worth spending the money on a new brush pack/regulator as it had already done 130,000 miles, so the whole thing was probably pretty worn out.

so replacing the alternator fixed the problem?

I just acquired from Ebay a spare of this same part number for my Polo with BBY engine.  Claimed to be off a car with <60k so ought to have more life left than the original on twice that many miles. Must have a look at the brush length tomorrow. Bit of a steal at a shade under £20.  

Yeah, replacing the alternator fixed the problem. I considered buying one on eBay and hoping it was ok, but I guess the warranty from the scrapyard swayed me.