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are there any good rebuild or reference guides for rebuilding the 150 amp alternators used in the NA spec P38s?

figure now is as good a time as any to learn how to rebuild these things.

thanks,

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Normally it’s just the brushes in the regulator that go, changed mine 5 yrs ago,, cost a fiver

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Not sure how close this will be, but this may help (Its a Disco in this case, but it would seem the main difference between the 150 amp and the smaller units is that the bracket for the 150 is different, so you can't fit a 150 in place of a smaller one without also swapping the bracket as well).

https://landroverforums.com/forum/discovery-ii-18/how-disco-ii-alternator-disassembly-51103/

Chris - When you say its normally the brushes that go, what sort of symptoms does that give? I get an initial failure to get charging voltage out of mine, which goes within around 1 mile of driving upto 14v (it typically sits around 11v until that point).

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That sounds like the brushes are getting towards the end of their life and are sticking a bit until it has warmed up.

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Cheers Richard. thats the news I was hoping for as its at least fixable with the parts available. Never used to be able to find anywhere selling the brushes and bits but they seem available for these on Ebay very easily.

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I used to rebuild my own alternators, there was a local firm called Start & Charge in Grimethorpe. He kept all the brushes and bearings in stock, if you turned up with your alternator would identify which bits you needed, sell you the bits for a couple of quid and tell you how to do the job. Don't know if they're still there.

Some will have heard my story about having an alternator fail on a bank holiday weekend when me and my son decided to go and explore Scotland? No chance I could get the alternator fixed or a replacement on the bank holiday and I knew I could fix it for a couple of quid back home... so I bought a generator, wired it's 12v output to a cig lighter socket and drove all the way home with the genny powering the car electrics, no heater or radio and only sidelights on.

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Your need a soldering iron, but they are easy to change, the other option which is dearer, is buy
a replacement regulator, but only a genuine Bosch,, there around the £50 mark,, I’d stick with changing the brushes,, beware, it’s a dirty job with all the carbon dust, wear gloves

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Best to get the slip rings really clean whilst you are in there too.

One gotcha issue with brushes is making sure you get the right composition. Hardness varies considerably between apparently same size brushes initially depending on the voltage and current involved. Wrong composition can either wear the slip rings (or commutator if its a motor or old school dynamo) or jam up in carriers. I've seen some where a DIY fix using "some brushes he had lying around" worked fine for a while then jammed up in the carrier. With witness marks to prove it. Then there was the guy who filed down some oversize ones, but not square.

Yet another reason why I tend to steer clear of real economy range replacements.

The only really nasty gotcha with aged alternators is a poor joint between slip rings and coils. The back joint is usually well buried and a total PIA to deal with. Fortunately its not common but something folk forget to check on an iffy alternator as it should be done at operating current. Had to fix one on a BMW flat twin alternator once. Idiot Germans bolted a near standard car alternator onto the end of the crank so the shaft was different. No exchanges, new price sky high and the local rebuilder wouldn't touch it "they don't come apart mate". Really. Hold my beer!

Clive

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Slip rings appear to be available - hopefully of decent quality though when i get round to pulling it off to sort it will find out I guess.

https://www.ebay.co.uk/itm/New-Bosch-Alternator-Repair-Kit-Small-6003-6303-Bearings-Slip-Ring-Wood-Auto/183979660526

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Clive603 wrote:

"they don't come apart mate". Really. Hold my beer!

Everything will come apart, it's whether it will go back together or not that is the bigger question......

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I seriously thought about rebuilding my Disco 2 120A alternator for my 4.0 Thor. My original 19 year old alternator was dying a slow death. The bearing had a grinding noise like it had sand in it and the voltage output was a constant 12.9 VDC.
I decided to bin it and purchase a remanufactured Bosch 150A alt for P38 for 90 quid off of eBay with a year warranty and it fit perfectly. I made an additional 0AWG cable and installed it to the alt frame going to the negative side of the battery for better grounding.
Now I'm getting 13.97-14.06VDC!

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i picked up a couple working, used alternators from Will Tillery for cheap.

i'll install the working ones and rebuild the ones coming out of my Rovers and keep those for trail/mall run spares.

thanks for everyone who replied.

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rebuild kits finally arrived.

however the voltage regulators are missing the green resistors that the old Bosch units have.

do i need to unsolder the resistors and install them on the new regulators?

anyone have any experience with the Maniac Electric Motors 13813RK rebuild kit? this is what i ordered but i'm wondering if i have the wrong Voltage Regulator.

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per Maniac Electric Motors the resistor is not needed.

their Customer Service rep emailed me back despite it being after hours and gave me all the info i needed.

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Jastutte are you in the USA? I’ve tried ordering the rebuild kit for my Marelli from Maniac, but it won’t accept my Canadian address. I’ve tried emailing them but no reply. Does anyone know another source for these kits?

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I have tried to ring them, email them, left messages ..... seems they have a typical American myopic view on trade.

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Harv wrote:

Jastutte are you in the USA? I’ve tried ordering the rebuild kit for my Marelli from Maniac, but it won’t accept my Canadian address. I’ve tried emailing them but no reply. Does anyone know another source for these kits?

I'm in Seattle so if you wanted to, have it shipped to me and I'll forward it over.
I'm surprised that they would care.

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Sounds like there's parts forwarding opportunities in all directions.....

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Thanks Beowulf. I’m not that far north of you in Kelowna. I’m not in immediate need of it and as soon as the border opens up I can get it sent to a mailbox in Sumas or Oroville for pick up. If I suddenly need it sooner I’ll take you up on your offer.

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Gilbertd wrote:

That sounds like the brushes are getting towards the end of their life and are sticking a bit until it has warmed up.

Finally got it inside today to swap the alternator over. Got the alternator off except for the cables, go to do that and discovered the smaller brown cable wasn't connected at all. There appears to be a black cable thats been added which heads back towards the battery. When its warmer going to investigate that better, it was too cold and wet today to get further into it, but reconnecting the brown cable to the point on the back seems to have stopped the low voltage when first started problem. And now I have a spare alternator plus the parts to fix one just in case as well!