Electrical Alternator (91 Mustang GT & 89 Lincoln Mark VII)

Jhp84

Member
Mar 2, 2019
96
11
18
california
Picked up a 91 Mustang GT as a project car for my son and I work on. The mustang alternator (75 amp?) drains the battery overnight (draws 3.08 amps); figured it is the diode. Picked up a 100 amp from the junkyard from a 1989 Lincoln Mark VII. Had it checked at autozone. Told it failed. Going to have to rebuild one of the two alternators. Wondering if they are both G2 versions, and if it makes sense to rebuild the 100 amp alternator. Do I need to change harness? Add separate fused hot line? Will it fit without having to modify the alternator bracket on the Mustang?

Thanks, Jhp
 
  • Sponsors(?)


Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,092
9,229
224
Massachusetts
There are numerous 01-04 v6 mustang 6G alternators on eBay for $40 shipped or so. I wouldn't spend a dime on a 2G alternator given the abundance of 3G and 6G Alts
 
  • Like
Reactions: Jhp84 and jrichker

jrichker

StangNet's favorite TOOL
SN Certified Technician
Mar 10, 2000
27,400
2,845
234
74
Dublin GA
lowendmac.com
@Jhp84


Mustang5L5 said:
There are numerous 01-04 v6 mustang 6G alternators on eBay for $40 shipped or so. I wouldn't spend a dime on a 2G alternator given the abundance of 3G and 6G Alts.
That's the best plan. The 6G supposedly does not require the alternator mount bracket to be modified.
Modifying the alternator mount bracket for a 3G is 10-15 minutes work with a rotary file and a drill or die grinder. Not hard to do, just be sure to clean up all the loose aluminum chips when you are done

See http://www.stangnet.com/mustang-forums/threads/3g-alternator-install-a-how-to.646825/#post-6673702

Alternator wiring.






Connect the fused 4 gauge wire to the alternator and the battery side of the starter solenoid.


Starter solenoid wiring 92-93 model cars.


Fuse holder from local NAPA dealer - Item#: BK 7821143 Price: $12.99
Product Features: Thermal Plastic Holder For AMG Type Fuse Rated From 100 To 300 amp.

217813.jpg


I would use a maximum of 120-125 amp fuse for the output wire that connects to the starter solenoid. Fuses are slow blow so it would pass 130 amps for a continuous runtime without blowing

Pre-fab 4 gauge cables with lugs already on the ends are available in most auto parts stores. Look for the starter switch to starter cables.
 
Last edited:

Jhp84

Member
Mar 2, 2019
96
11
18
california
Thank you both for the recommendation on the G6. Taking my son to see if we can pull one from the junkyard (seem to be number of 01-04 on the website). While we are there, anything else we should consider to pick up for the swap?

On an unrelated note, would we be able to use the electric fan and radiator from the 01-04 on the 91?

Again, thanks. Good to be working together with my son instead of arguing over other things.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,092
9,229
224
Massachusetts
Radiator no.

Fan really all depends on if it will fit and custom mounts. I'm using a 94-95 fan in my car
 

Jhp84

Member
Mar 2, 2019
96
11
18
california
No luck yesterday finding a G6 alternator in the junkyard. Heading over to another junkyard to continue our search for a G6 alternator for our project 91 Mustang GT. Any other vehicles/years from which we could grab an alternator that would fit, without having to modify the bracket (Taurus? Thunderbird" etc.). Thx, jhp
 

Blown88GT

Founding Member
Nov 13, 1999
2,041
468
134
Palm Beach Gardens, FL
Easy to tell 2G from 3G.
2G has external fan
3G & above have internal fan

I've had the original working 2G sitting in a box for 25 years.
Free to good local home.
 

Jhp84

Member
Mar 2, 2019
96
11
18
california
The clearancing for the 3G alt is minimal. 5-10 min with a grinder or even a dremel.


If you want the 6G I think it's 01-04 v6 stang only. The 4.0 sohc explorers might have a similar one.

https://rover.ebay.com/rover/0/0/0?mpre=https://www.ebay.com/ulk/itm/332994839300

I'd just offer up $35-38 for this shipped with a 60'day warranty
Thanks for the suggestion. I guess it would be easiest to purchase, but my goal is to keep connected and learn together with my son about his project car before he finishes high school this year. Been a few rough patches between us these past years. Treks out to the junkyard give us a neutral place to chat without interruption, to shoot the bull...

Anyway, quick follow up question, what are the big differences between the 3G vs 6G, particularly for this vehicle (if any).

Hop
 
  • Like
Reactions: Mustang5L5

mikestang63

SN Certified Technician
Aug 27, 2012
9,901
6,685
204
In the garage
3G's are everywhere in s JY.

94-96 mustang
94-96 t-bird 3.8
95-96 windstar 3.0
93-96 e series vans f series truck w 4.9 i-6
3.0 taurus
94-96 cougar 3.8 v6
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,092
9,229
224
Massachusetts
Anyway, quick follow up question, what are the big differences between the 3G vs 6G, particularly for this vehicle (if any).

Hop
Case size mostly. The 3G are all mostly 130a. I believe the 6G is 110A

Clearancing is minor really. I have one and it was an easy install.

Great reason for heading to the junkyard. Good luck in your search and hope you have a great time doing it.
 

Jhp84

Member
Mar 2, 2019
96
11
18
california
Quick update. Field tested three 6G alternators at the JY. Two passed the diode test and both put out current when we spun the pulley with the impact drill. One, however, came to a fairly fast stop when we removed the drill. We figured the bearings were wearing out. So, we picked up the one from a 2003 Mustang.

Came back, and it fit in the bracket without a hitch. We will need to replace the regulator connector, as the 2G one doesn't fit. Presume we can cut it off and solder the one that we removed from the 6G at the JY. As for the 4 ga wire to the alternator output. if I understand correctly, we put a short run from the starter solenoid to a 125A fuse (which we mount to the sidewall? under the battery?) and then connect to the alternator, running the line between the radiator and the grill. Is that right? And, we simply forget about the other power connector (other than sealing). No need to worry about the two orange/black wires nor the white wire either?

Btw, new to this forum stuff. Noticed the water pump has fluid coming from the weep hole. Do I start another thread on the to get advice on that?

Thanks, you folks have been helpful and kind. Jhp
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,092
9,229
224
Massachusetts
Stator wire isn't used with the 6G

Need to solder the green to the green and yellow to the yellow on the regulator plug
 

Blown88GT

Founding Member
Nov 13, 1999
2,041
468
134
Palm Beach Gardens, FL
...

1. Came back, and it fit in the bracket without a hitch.
2. We will need to replace the regulator connector, as the 2G one doesn't fit.
3. Presume we can cut it off and solder the one that we removed from the 6G at the JY.
4. As for the 4 ga wire to the alternator output. if I understand correctly, we put a short run from the starter solenoid to a 125A fuse (which we mount to the sidewall? under the battery?) and then connect to the alternator, running the line between the radiator and the grill. Is that right?
5. And, we simply forget about the other power connector (other than sealing). No need to worry about the two orange/black wires nor the white wire either?

6. Btw, new to this forum stuff. Noticed the water pump has fluid coming from the weep hole. Do I start another thread on the to get advice on that?
...
1. https://alternatorparts.com/ford-type-3g-4g-6g-series-high-output-alternators.html
2. Correct
3. I assume so.
4. Correct
5. Correct
6. Replace water pump.
 

Jhp84

Member
Mar 2, 2019
96
11
18
california
1. https://alternatorparts.com/ford-type-3g-4g-6g-series-high-output-alternators.html
2. Correct
3. I assume so.
4. Correct
5. Correct
6. Replace water pump.
Ok, so let me follow up with a water pump question. When I grabbed the ill-fated alternator from the Lincoln Mark VII on our first trek out to the JY, I also pulled the water pump off of it. At the time I thought it would be prudent to snag it, just in case. Given that the alternator turned out to be the wrong size and defective (see picture), I am now wondering if I could use the water pump I picked up at that time. If not, from what other cars (models/years) could I pull a replacement water pump. Or, does it make more sense to get a rebuilt or new one?

[At the JY where we got the alternator from the Mark VII, we also pulled the radiator hood. Turns out the overflow container and its location is different in the Mustang. The Mark VII didn't have a sensor in the overflow. So, lesson learned for my son and I: Take pictures beforehand or know your own car better.

We also thought about grabbing the fuel rails and a couple of sensors, but we weren't sure if these would fit. Does it make sense to return to the first JY and get these as back up?]

Thx, Jhp
 

Attachments

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
33,092
9,229
224
Massachusetts
Hard pass on the JY water pump. Who knows how long it's been sitting and what's that's done for the internals.

I would just grab items as needed for now. The mark 7 motor does have some differences. The basic long block stripped down is the same, but items like assessories, and pullies and such do differ. Unsure about the fuel rail though.
 
Thread starter Similar threads Forum Replies Date
8 General 3g alternator upgrade on 1989 AscMclaren mustang. Special Production 2
347Fastback Engine Mustang Drivers Side Alternator mounting Fox 5.0 Mustang Tech 3
0 Backfire and stall, won’t crank 1996 - 2004 SN95 Mustang -General/Talk- 3
Enzio Engine New Fan Shroud, Thermostat, Alternator Belt 1974 - 1978 Mustang II Talk & Tech 2
2 Electrical 1982 Mustang 5.0 Alternator wiring help NEEDED Fox 5.0 Mustang Tech 3
bluelx347 Expired 1986-93 Ford Mustang Sve 130 Amp 3g Alternator Upgrade With Braket - $125 Engine and Power Adder 0
M Misfire Hesitation And Popping Sounds SN95 4.6L Mustang Tech 11
R 02 Mustang Alternator Issues SN95 4.6L Mustang Tech 9
H 84 Mustang With Odd Electrical Issue Fox 5.0 Mustang Tech 5
A Battery Light 2005 - 2014 S-197 Mustang -General/Talk- 0
S 1967 Mustang Alternator Charging Problem 1965 - 1973 Classic Mustangs -General/Talk- 0
N Need Some Help Please With My 2000 3.8 V 6 Mustang My Alternator The Welcome Wagon 2
S 05 Mustang Gt Alternator Swap Issue 2005 - 2009 Specific Tech 4
RubiconTJ Electrical 2006 Mustang Gt 4.6 Alternator Install Video 2005 - 2009 Specific Tech 0
A Replacing 2g Alternator 87 Mustang Gt Need Help!! Fox 5.0 Mustang Tech 26
KyleEBK Dual Alternator Bracket For Mustang 5.0 Fox 5.0 Mustang Tech 14
chgovfk Alternator Needed For 351 W Swap Into 90 -93 Mustang? Fox 5.0 Mustang Tech 1
MustangMando 91 Mustang Alternator Wiring 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 1
MustangMando 91 Mustang Alternator Wiring To A 68 1965 - 1973 Classic Mustangs -General/Talk- 5
Nc14 1994 Mustang Gt Keeps Blowing Alternator Fuse 1994 - 1995 Specific Tech 6
J 94 Cobra Alternator In A 86 Mustang 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 2
Igofaster13 Expired Mustang 3g Alternators 86-93 5.0 302 + Harness Clips 94-95 Fox Body - Engine and Power Adder 3
MustangMando 68 mustang alternator upgrade Classic Mustang Specific Tech 4
LarsD Anybody have a pic of the alternator bracket setup for a 67 Mustang? Classic Mustang Specific Tech 5
T 83 mustang alternator/killswitch question Fox 5.0 Mustang Tech 4
mustangguy65 Please Help 65 mustang alternator wiring Classic Mustang Specific Tech 2
brienjohnson200 1993 Mustang---Alternator not charging----PLEASE HELP Fox 5.0 Mustang Tech 15
S 94 HO alternator in a 93 mustang Fox 5.0 Mustang Tech 2
M autozone 130 amp 94-95 mustang alternator warranty help. 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- 11
chepsk8 Alternate 69 Mustang serial number locations Classic Mustang Specific Tech 6
callys Painless Harness in 70 Mustang with 3G alternator? Classic Mustang Specific Tech 5
T 1986 Alternator in 1985 Mustang? Fox 5.0 Mustang Tech 1
T 86 Alternator In 85 Mustang Fox 5.0 Mustang Tech 1
CU racing State patrol mustang alternator Fox 5.0 Mustang Tech 14
S mustang II alternator wiring 1974 - 1978 Mustang II Talk & Tech 4
sam woodson 1986 Mustang with 135 Amp Boss alternator and Amp meter? Fox 5.0 Mustang Tech 4
2 late model alternator in a 69 mustang? Classic Mustang Specific Tech 8
P 88 mustang gt 5. need alternator Fox 5.0 Mustang Tech 2
8 89` 5.0L Mustang 4guage 3g alternator power wire length Fox 5.0 Mustang Tech 1
P Has anyone installed a one wire chevy alternator in a classic mustang? Classic Mustang Specific Tech 8
Stang8URMPRT 1 wire Alternator for 83 Mustang 5.0 Fox 5.0 Mustang Tech 7
M 68 Mustang Alternator not Charging Classic Mustang Specific Tech 7
88Interceptor 3g alternator upgrade on a SSP Mustang Fox 5.0 Mustang Tech 3
SilverStallion Alternator Bracket Change to Billet Bracket on 2000 Mustang GT - Help Pls.>>> SN95 4.6L Mustang Tech 0
philly029 83' mustang alternator upgrade, need help! Fox 5.0 Mustang Tech 3
8 Electric fan problem Fox 5.0 Mustang Tech 2
J Alternator bolts 1996 - 2004 SN95 Mustang -General/Talk- 0
D New Motorcraft 2G Alternator Fox 5.0 Mustang Tech 6
91GTstroked Engine 3G alternator ground questions. Fox 5.0 Mustang Tech 12
B Help please. wiring for alternator upgrade 2010 - 2014 Specific Tech 5
Similar threads