4 alternators in 5 years - any clues..?

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Jan 13, 2007
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Orange, NSW
My truck is a '85 FJ60/62 crossover (Aussie), it has the 3F carburetor engine but the circular headlamps... Anyway, it is pretty much standard on the electrics front, except for a pre-made wiring loom I fitted for the headlamp relays, bought from ARB.

The trouble is I have blown 4 alternators in 5 years - I have no idea how the old the first was (no previous records from the owner regarding alts, and I am only the second registered owner), the second was probably mud ingress as it happened after pulling someone out of the mire, the last two..? Not sure... Both were after several '000km of road-going activity. The splash guards from the wheel-wells are missing on the alt side and so the alt does get a bit of spray from the road, but nothing that much (I live in Aus - permanently dry!).

Any ideas..? I took it to an auto-sparky last week for them to check it over and this resulted in the fitment of the 4th alternator and b*gger me, this week the thing is over-charging again! This morning (on the way back to auto-sparkies) the alt lights began to flicker again at a constant 60kph in 4th gear. The last two failures were pre-ceeded by over-charging (instead of the usual rock steady 14v, it goes off the dial and the headlamps go like search lights.

The electrics are relatively simple, so any ideas what it can be? I'm stumped... :(
 
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In the valley of the Great Salt Lake.
Are all of the replacement alternators from the same source? Over here, there are very few rebuilt alternators that will last very long. I never use rebuilt alternators or starters, I always buy new ones. But before you lay out the money for a new one, you need to put an ammeter in circuit with your alternator to see the amperage draw from the alternator. If it is within a reasonable range (you need to determine whether you have a 40 amp or a 60 amp alternator), and since you have pretty much ruled out moisture, then that leaves poor quality rebuilds as the most likely cause. I'd get a Toyota one, or maybe do a mod to a GM alternator (do a MUD search).
 
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Do the Alts in NSW have the regulator 'built in' or is it a seperate box ?

(My FSM shows a few different configuations of Alt, Regulator )

The problem sounds more like regulator than Alt.
Do check the smaller wire lines "to" the Alt . . .(Kling-ons comment, above)
. . if it doesn't sense the battery voltage, the regulator will 'overdrive' the Alt....
 
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Not knowing the alternator design on your vehicle, does it have a second or third wire that is relativly small in size compare to the other wires? If there is, that may be the feedback wire that goes back to the voltage regulator. Its duty is to check the voltage from the electrical system and adjust the output to the b+ wire to the battery. Also, check for resistance from alternator body to battery negative terminal. check for resistance from B+ to battery positive.

Lastly, when was the last time you had the battery replaced? Check for a voltage drop under load. If one or more plates are shorted, it will make the truck hard to start, and put more load on the alternator.

Lastly, if you dont want to do this, take it to the best automotive electrical shop in town and have them check for resistance drops thought the charging circuit.
 

Rigger

Ramble Tamble
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I'd echo two things that were already mentioned:

1) Use a Toyota alternator, not a cheapie.

2) Check to see that you don't have a bad battery.

Good Luck!
 
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Townsend/Big Sky, Montana
get a multimeter and check all electricals and diagnose the problem to where it is at.

i ALWAYS check ALL connections AND ALL grounds before even looking at what I think an electrical problem is.


is the voltage regulator in the alt. or seperate?
if it is seperate, I would replace that first.

could also use multimeter to check all electricals inc: ignitor/coil assembly, starter, etc.

like Klingon said it could be a simple as one crossed wire or bad connection. since you said something about aftermarket electrical lights, that is probably where the bad connection is at.
also check the fuse box for blown fuses or crossed wires as well.

could even be a bad/melted connection in the ignition switch...
 
Joined
Jan 13, 2007
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Orange, NSW
Thanks.

The truck is at a shop but I thought I'd do a bit of background reading... Hadn't thought about the third wire, I have one on my MG, but can't remember the back of the truck's (funny - I haven't looked at the MG's in over 3 years but I can remember it clear as day, was staring at the Trucks yesterday and can't remember!) .

The voltage regulator was changed on the last alternator. The battery was changed on the one before. WHilst these could be an issue, I don't think they are at the moment. The fact that the 4th alt has gone within two trips (each of 250km) makes me wonder if it is either the regulator, or perhaps the return wire if there is one. I assume there must be because the regulator is seperate to the alt in this model.

Will call the shop tomorrow and enquire about the return wire. Cheers ~PHIL
 
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Orange, NSW
This was one of my thoughts - but the alternator belt at least is pretty good. The others are tight and do not directly connect up with the alt...
 
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Oct 12, 2004
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Are all of the replacement alternators from the same source? Over here, there are very few rebuilt alternators that will last very long. I never use rebuilt alternators or starters, I always buy new ones. But before you lay out the money for a new one, you need to put an ammeter in circuit with your alternator to see the amperage draw from the alternator. If it is within a reasonable range (you need to determine whether you have a 40 amp or a 60 amp alternator), and since you have pretty much ruled out moisture, then that leaves poor quality rebuilds as the most likely cause. I'd get a Toyota one, or maybe do a mod to a GM alternator (do a MUD search).

Can you ever actually get a new alt or starter? Even from Toyota they are remann, right?

Zack
 

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