Is This A 3g Alt?
- Thread starter billison
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mikestang63
SN Certified Technician
That's a 2g. Now someone could have rebuilt it with better internals, to run higher amps but they left the stock 
wiring intact?
Here is a side by side of the 2g and 3g case.
wiring intact?Here is a side by side of the 2g and 3g case.
not a 3g, the fan would be internal, and the white wire on the bottom would have a smaller plug, and there would be a larger power wire.
Dunno why, but the 3g swap always stumped me till just now... I just gotta get the alt, and the hardware, use the plug, cut the other plug it goes to the charging bolt along with a think wire that will go to the solenoid, and connect the white wire to the stator... Once I get though my needed fixes, this is at the top of my list fallowed by a torus 3.8 fan.
mikestang63
SN Certified Technician
I know this has been beat to death, but IMO do NOT cut any wires. There is no need to. Simply splice into the stator wire on the old 2G wiring with either a female adapter or get the adapter from the boneyard. The D shaped plug from the 2G transfers over to the 3G. Run at least a 4G power wire from the post on the 3G to the battery side of the starter solenoid with an inline 150 amp fuse. Make sure you add another 4G ground wire from the block to the chassis.
mikestang63
SN Certified Technician
Just tape off those wires and tuck them back. IMO do NOT hook up the2 black/orange wires to the post on the 3G. Those wires are notorious for burning up with only the load from the 2G. I've done dozens of Mustangs this way with no problems.
They were the charge wires for the 2G. Your 3G will have the fused 4 AWG power cable noted above, so these are unnecessary. But if you connected them and your 4 AWG cable blew a fuse or something happened which affected the integrity of the cable (a terminal falls off, etc), power would try to go through those two little wires and that would not be good. As noted, insulate the ends of those two wires really well (they're still connected to battery power on the other end).
mikestang63
SN Certified Technician
If you get a large case 3g from a 1994-2000 mustang, you will need to notch the alternator bracket to get the alternator to fit. Mark the part of the bracket with a marker and you can use a dremel, a grinder, or even a small hacksaw. You'll see what I mean when you put the bottom bolt in and swing the alternator in. Also, the stock top bolt won't work. You'll need a new bolt and nut. I forget the size but am sure others will chime in.
I guess my final question before I start gathering parts is this, my ground needs to be replaced with a 4g wire, Do I just run a wire from the block to the battery or do I run it to where the ground on the battery connects to the frame? thanks.
mikestang63
SN Certified Technician
Yep, that's where I ran mine. You can also add it to the ground strap on the back of the engine to the firewall. Can never have too many grounds IMO.
yes you can. Too many grounds creates ground loops.
When in doubt, ONE good solid ground beats many grounds.
mikestang63
SN Certified Technician
Maybe I'm misreading your post. First time I've heard of only having one ground wire in 30+ years. Stock, they come with several grounds that I can think of
1. main power ground is from engine block to neg post on battery for starter and alt.
2 secondary power ground is between the back of the intake manifold and the driver's side firewall for accessories, a/c and interior.
3. ECU has its own ground split off the neg battery cable
4. ECT, VSS IAT, TPS all have their own grounds
5. TFI has its own ground
6. HEGO orange ground for the )2 sensors from harness by the salt and pepper connectors the firewall
If you have a trunk mounted battery, you also have a ground back there. Electric Fan or water pump? Another ground. In theory, one ground wire for everything would be great. I don't see how you do it but you're never to old to learn something.
That's different.
I think did misread your posts. What i was referring to was the current trend in the import world to basically ground the hell out of anything and everything...like so.
What you are referring to is proper grounding technique. But tossing on 3 engine to body grounds just because there was an empty lug is a different story.
I think did misread your posts. What i was referring to was the current trend in the import world to basically ground the hell out of anything and everything...like so.
What you are referring to is proper grounding technique. But tossing on 3 engine to body grounds just because there was an empty lug is a different story.
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mikestang63
SN Certified Technician
That's different.
I think did misread your posts. What i was referring to was the current trend in the import world to basically ground the hell out of anything and everything...like so.
What you are referring to is proper grounding technique. But tossing on 3 engine to body grounds just because there was an empty lug is a different story.
LMAO!!! That is some funny shiiiiit... Between the fart tubes, 10 foot wings, neon lights, 8000 stickers that add 100hp, fire extinguishers, 1000 watt stereos, lambo doors, and NOS bottles that arent hooked up (nitrous oxide to us old timers), they take stupid to a new level.
Try and beat this one....
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