Mr_Roboto
Full Access Member
OK, my stock alternator was making some nasty noises from the bearings, so I figured what better time to do what? MOD!
I happened to have a 130 amp 3G reman off of a van I had scrapped (92 300 I6). One off of a Taurus will also work.
Now if you are going junkyarding, you want to be able to tell the difference between the 95 and 130 amp units. The front of the 3G is full of holes, in between the stiffening ribs you will see 4 small holes on the 95 amp, and 2 large holes on the 130 amp (see first pic below).
Make sure that you get the plugs that go with the alternator, and try to get at least 2 inches of wire, the more the better. Also make sure you keep the top (short) mounting bolt for the 3G.
This is the diagram that I used to wire up the alternator: http://www.bcbroncos.com/3ginstall.pdf
Note that the Light Green / red wire that goes to the "I" terminal must be cut off of your existing voltage regulator harness, it is long enough to pull it out of the loom and run it to your new alternator.
Also the "A" terminal shows being connected to the battery wire on the back of the alternator. I recommend NOT taking this shortcut, and instead running this wire to your battery +. The reason is that the regulator uses this wire to see battery voltage, and if you have a battery isolator or a high load condition, you will end up with a low charge voltage.
I discarded the factory battery wire (B+) which was in poor condition, and ran twin 12 awg wires direct from the alternator to the battery. I jump start semi trucks with my truck and I don't fool around! A high amp fuse is recommended in this circuit for safety. Do not simply re-use the factory wire, it cannot handle the amps that the 3G can produce. At a minimum you must run a second, parallel wire to the battery itself (the factory wire runs to the GP solenoid and from there to the battery).
The alternator bolts right in, you will re-use your existing bottom bolt, and use the top (metric) bolt that came with the 3G alternator.
Those with V-belt drives, you will have to shim your V-belt pulley out slightly (about 2mm) to keep it from rubbing on the alternator housing. I used a flat washer that was under the pulley nut. There is just BARELY room for the pulley nut to thread on, I had to leave the lockwasher off. I recommend using a threadlocking compound for safety.
Wiring at alternator:
Wiring at battery:
Ed.Additional comments from Mr. Roboto...
Q. How do I get one of these alternators?
A. Ask for a alternator for a 92 E250 with a 4.9L and WITH A/C. This will get you the 130 amp unit, and is what I installed.
Be prepared for a hefty core charge and an expensive alternator. I'd look for a good used one on eBay or at the junkyard, you will need the wiring anyway to do the conversion.
I happened to have a 130 amp 3G reman off of a van I had scrapped (92 300 I6). One off of a Taurus will also work.
Now if you are going junkyarding, you want to be able to tell the difference between the 95 and 130 amp units. The front of the 3G is full of holes, in between the stiffening ribs you will see 4 small holes on the 95 amp, and 2 large holes on the 130 amp (see first pic below).
Make sure that you get the plugs that go with the alternator, and try to get at least 2 inches of wire, the more the better. Also make sure you keep the top (short) mounting bolt for the 3G.
This is the diagram that I used to wire up the alternator: http://www.bcbroncos.com/3ginstall.pdf
Note that the Light Green / red wire that goes to the "I" terminal must be cut off of your existing voltage regulator harness, it is long enough to pull it out of the loom and run it to your new alternator.
Also the "A" terminal shows being connected to the battery wire on the back of the alternator. I recommend NOT taking this shortcut, and instead running this wire to your battery +. The reason is that the regulator uses this wire to see battery voltage, and if you have a battery isolator or a high load condition, you will end up with a low charge voltage.
I discarded the factory battery wire (B+) which was in poor condition, and ran twin 12 awg wires direct from the alternator to the battery. I jump start semi trucks with my truck and I don't fool around! A high amp fuse is recommended in this circuit for safety. Do not simply re-use the factory wire, it cannot handle the amps that the 3G can produce. At a minimum you must run a second, parallel wire to the battery itself (the factory wire runs to the GP solenoid and from there to the battery).
The alternator bolts right in, you will re-use your existing bottom bolt, and use the top (metric) bolt that came with the 3G alternator.
Those with V-belt drives, you will have to shim your V-belt pulley out slightly (about 2mm) to keep it from rubbing on the alternator housing. I used a flat washer that was under the pulley nut. There is just BARELY room for the pulley nut to thread on, I had to leave the lockwasher off. I recommend using a threadlocking compound for safety.
Wiring at alternator:
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Note the 2 large holes between the stiffening ribs that indicates the 130 amp alternator.Wiring at battery:
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I connected the battery wires plus the "A" wire here. The larger wire is for my hard wired jumper cables.Ed.Additional comments from Mr. Roboto...
Q. How do I get one of these alternators?
A. Ask for a alternator for a 92 E250 with a 4.9L and WITH A/C. This will get you the 130 amp unit, and is what I installed.
Be prepared for a hefty core charge and an expensive alternator. I'd look for a good used one on eBay or at the junkyard, you will need the wiring anyway to do the conversion.
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