120A Alternator Refurbish

[naki_k]

Has anyone ever refurbished a 120A Alternator?
I was going to try once before, but could not undo the pulley nut. Now I have an impact gun, it comes off in a second! So a much better chance to have a go.
I watched a few You tube videos to get some kind of idea, but I suspect there will be a specific weakness of these Denso units. Any idea what parts fail?
I am hoping that most of the parts are available new. I know some parts are on JCP even.

Has anyone on here done one?

These units have quite a high failure rate now I think. Especially after a time of no use.

[katar83]

Nice to have an impact gun on hand, dont you think? Makes some of the jobs so much easier
No idea what's failing on these specifically but generally its usually:
1. brushes
2. rotor rings
3. voltage regulator
4. bearing
5. some other mechanical parts

Back in Poland, most of the alternators get refurbished, the cost is almost always between £20 and £30 and in some cases where more parts are needed its probably up to ~£50-£60 max for a fully refurbished unit. I swapped two alternators on my Jaguars, if I had the tools(like I do now) and parts at the time I would definitely try to fix it first.

[naki_k]

I think it’s becoming more of a necessity with these 120A units with a high failure rate.

As always, the right tools simply make things possible.

Everything is repairable, it’s just down to money, tome and convenience really.

I just had a quick look on JCP.
The parts most likely to be needed are NLA or silly expensive. So I will likely find the part numbers off the parts and net search.

https://www.jaguarclassicparts.com/uk/j ... r-assembly

Incidentally, this unit I have spins as normal, so I know the bearings are good.

I had one refurbished a number of years ago, and multiple parts were replaced. Maybe they just swapped everything? Rather than diagnosing which component actually failed? The rectifier and regulator were changed for sure, as they are visible through the rear vent, and were clearly new. When I find the part numbers, I can price them up anyhow.

[katar83]

Silly prices indeed! I'd go with brushes check first, they can be bought on ebay for just a couple of £ and regulators seem to cost ~£20 too so not too bad.

[katar83]

Just had a quick look and the voltage regulator can be bought for £20 on eBay, 126000-1200

Full parts list and some numbers(that can be used to find them in UK) can be found here:

http://www.ebay.com/itm/ALTERNATOR-REGU ... 1528718571

[naki_k]

Just had a quick look and the voltage regulator can be bought for £20 on eBay, 126000-1200

Full parts list and some numbers(that can be used to find them in UK) can be found here:

http://www.ebay.com/itm/ALTERNATOR-REGU ... 1528718571

That would be nice and easy if it was just that, as that can be changed from the back without even opening the main unit.
Thanks for the link.

[naki_k]

And the rectifier. Well I haven’t checked the part numbers but it’s looks exactly the same if the pics are real.

http://www.ebay.co.uk/itm/Jaguar-XJ-XJ8 ... ect=mobile

Plus a uk based supplier for the regulator

http://www.ebay.co.uk/itm/Jaguar-XJ6-xj ... 0005.m1851

And the Brush. All three parts from the same seller.
https://m.ebay.co.uk/itm/Jaguar-XJ-XJ8- ... mwBanner=1

[katar83]

Yes and I suspect 90% of the faults will be voltage regulator/brushes related so well worth checking.

[naki_k]

Ok, I may just get those ordered then

[naki_k]

Those three parts are now ordered. £55 total.
Ok so the cost is not far off that of another used alternator, but if the weak points are replaced with brand new parts, it’s a better guarantee that it should last a long time?