1988 Ford F250 7.3 IDI Diesel 1G to 3G Alternator Upgrade

This is a how-to swap a 1G to a 3G alternator for a 1986-92 Ford with the 7.3 IDI diesel.

[@AdmiralBosch19]

Gonna be doing a 3g swap this weekend on my 89, thanks a bunch for filming this

[@hiphopwong]

Great video, great upgrade. I ran into similar problems but I found out it was the wiring harness female plug that had 1 slot collapsed. Voltage regulator and alternators both checked out but the female wiring harness plug was so brittle one of the slots was not pinching the tang on the voltage regulator.

[@coreywood3543]

Dude, this video is so great. I just ordered all the parts to make this swap on my 90. This video walked me right thru it. Thanks.

[@GetOffMusic]

Where did you order parts from

[@robertmaclauchlan2981]

This is great info I'm going to do the conversion on my 1988 f450 7.3 awesome!!!

[@benjaminworkman3259]

Thank you so much for this video. I've done a conversion to the serpentine belt but never knew about this one it's so easy

[@firfyter]

Awesome video! I'm going to do this to my 87 F350. Thank you so much.

[@unclebuzz6913]

Yep I have a 91 f350 and the wires are atrocious,as it was my pops,and he did a lot of weird stuff to them. However he kept driving it until they took away his license,than I bought it at a reasonable price,and the charging has been erratic. Thanks for the tip I will be checking into it.

[@Eskobear011]

Great video, did not know how to swap, I do now

[@TonaldDrump686]

Got mine last week from a starter-alternator shop here local. Truck is 1989 f-250 7.3idi The one I got had connections at 3 o’clock which is fine. I had too much faith in the threads I read before hand. So I asked alterntor people to clock it to 12 o’clock. 3 o’clock would have been better due to fuel filter head location. Mine also had belt misalignment when just bolted on. It was too far back so I ground 1/8” off the front “ear” of the lower mount-which Is really heavy cast iron so no concern with strength. I also ground a bit off the alternator itself, After bolting on it became apparent that I didn’t need to grind the alternator. No biggie, One .035” washer in front and 1/4” spacer in rear. Belt alignment is sooo much better now. I can’t understand why more people doing this didn’t notice the misaligned belt. When alt belt is perfect, vacuum pump belt is a bit off. So I’ll split the difference favoring the alternator. I ran out of daylight today Xmas day. I’ll source a big fuse tomorrow and some big wire. My pulley nut has a thread exposed which I don’t prefer. The fórumes mentions this and alternator shop said it’s ok so I’ll try not to worry. The original alternator lasted a long time but after a new voltage regulator it still would show 12.2 athe rhe battery’s. And then go up the 16-18 with no load. Sorry for the long winded post, I’ll be happy if rhe 3g solves my charging problem.

[@roberttaylor8918]

I did not have any alignment issues with my alternator to vacuum pump but I can imagine it happening, especially now that these trucks are over 30 years old. I am glad this video helped keep your truck on the road. My original alternator lasted decades but the replacement ones were complete crap. Let me know how it works out for you.

[@fasteddie5371]

I’m fixing to have to do this thanks for the video bud

[@Troyisbig]

Sorry Robert - I see your answer in a previous comment below! Thanks!

[@JClinger1991]

Ordered up the altenator and pigtail off rockauto. I'm having the exact issue you had. 1 week in between repairs both the voltage reg and now altenator have died again. do you have a part number for the Mega fuse you are using?

[@tdb4297]

I'm putting the fourth alternator I've got from O'Reilly's in my Bronco right now so I guess it's not just me

[@roberttaylor8918]

Dude if you can swap it for a 3g alternator with at least 100 amps. I have driven about 10k miles now and I never get any kind of headlight dimming or charging issues. Truck starts every time even after sitting for months.

[@highplainshollarhomestead3188]

That part number suggests it's a 2G alternator....is it a 3G?

[@highplainshollarhomestead3188]

Thanks for the video.

[@GetOffMusic]

So the blue wire goes to the lead post on the alt Red wire splices into the green to connect the garnets where did the yellow wire go ?

[@roberttaylor8918]

It connects to the stator on the alternator. it's labelled as S.

[@napsterproductions709]

Cool video! 🤙🤙

[@rickygala745]

I have a f-250 6.9 idi you think i can use the same part number alternator?

[@roberttaylor8918]

I think it should bolt right up.

[@margueritesmitheram3389]

Perfect thankyou

[@DatNESGuy85]

So I just completed this install a couple days ago, but I get a battery light and no charge. I get 12 volts all along the battery cable from the solenoid to the B+, so I don't think it's anything related to the 4 gauge line. I suspect it's related to the I wire "pigtail" connection: I cut the wire from the regulator and it meets with the wires from the tach. Spliced it to the open I wire with plug connections similar to how you did. Is it not getting enough voltage because I didn't solder? Stator and sensor wires seem good too. Any help is appreciated.

[@roberttaylor8918]

Check for 12 volts from the green wire with the key on. The green wire gives voltage to the alternator to power the alternator to generate a current. Alternators do not have magnets and they generate electricity from a small amount of power (green wire) to generate a magnetic field.

[@roberttaylor8918]

Also, check the connections on both terminals at the S, and I on the alternator.

[@roberttaylor8918]

If you are still having issues go have the alternator tested.

[@DatNESGuy85]

Thank you for the response. I was able to get the alternator to charge when directly contacting the I wire with the battery positive post. I used a meter to test my green wire, and it looks like it's putting out the same amount of voltage as the batteries? Weird that it won't work. I'm about to try my I line connected from the glow plug relay ignition source instead.

[@DatNESGuy85]

Running a second connection from the glow plug relay to the I wire pigtail did the trick. My only issue is a bit of voltage fluctuation at idle. 14.4-15 volts or so.

[@justawhiteguy3008]

So, I don’t need to run any wires to my starter? And nothing directly to the battery itself ?

[@roberttaylor8918]

No, there is a battery distribution block that you run the main hot wire from the alternator. Re-watch the video and you can see where I tie in the 4 gauge hot wire from the alternator to the battery distribution block, don't forget the 175 amp fuse.

[@rollfablife3363]

Where do I get the pigtail at

[@cchoice4919]

what would you recommend for a 1990 ford f350 idi???... having trouble finding a 3G alternator for that year..

[@roberttaylor8918]

Mine was a 88 which is about the same. Do you have the twin V-belt or serpentine?

[@zavalalandscapegroup9612]

i am a little confused with the wiring. you mentioned a ford forum at the end, could you give me a link please! thank you

[@roberttaylor8918]

Here is a helpful link. www.ford-trucks.com/forums/1502268-87-f-250-idi-1g-to-3g-alternator-upgrade-issue.html

[@zavalalandscapegroup9612]

@@roberttaylor8918 Thank you so much!! one last question and ill leave you alone i promise. on the mega fuse. How many amps should i get? thank you!

[@roberttaylor8918]

@@zavalalandscapegroup9612 175amp

[@kyleshears2039]

Did the 3G upgrade affect the stock volt meter's ability to work?

[@jacobbatchelder344]

Hey man, I was wondering if you had to use different length belts as the pulley is smaller?

[@roberttaylor8918]

No, I never needed to change the belt size. Just make sure the pulley on your old alternator is the same size as your new alternator

[@philackey]

My belts are loose even at maximum, did they stretch or is the pulley on the new alternator wrong? It looks the same as the old one, but shinier

[@roberttaylor8918]

I would get a belt that is an inch shorter and try that. I did not have any belt issues with my truck

[@djpitr]

Can you share the link to the forum ?

[@roberttaylor8918]

www.ford-trucks.com/forums/1156489-how-to-3g-install-for-83-92-idis-3.html start reading at posting # 35

[@zavalalandscapegroup9612]

where can i find the pig tail and all the other materials. than you!

[@roberttaylor8918]

eBay and Napa. Look up the part number at Napa. eBay do a search for 1g to 3g pigtail.

[@mattg7952]

You can get everything from a junkyard. 91-95 Taurus/Sable with the 3.8 v6. Just did mine today

[@Adam-qe9br]

@@mattg7952 thank you!

[@williamosborn989]

Where did you get the pig tail for the alternator?

[@roberttaylor8918]

Ebay

[@BRENDAJASON1]

What 3g alt did you get

[@roberttaylor8918]

See video for part number

[@Troyisbig]

Robert - I tried to find the 3g pigtail - I didn't catch where you got it - could you give me a part number? Thanks!

[@roberttaylor8918]

Troy this should work. www.vintageautogarage.com/3G-Ford-Alternator-plug-connector-FL4-p/FL-4.htm?gclid=Cj0KCQjw-Mr0BRDyARIsAKEFbeeExlVg21shCCwaxJ9WvXaCAd9hyMisYSMRqkeD5YTahGmGpJHmI9EaAnbYEALw_wcB

[@judaford2724]

Is heavier gauge wire needed for the harness after the alternator swap?

[@roberttaylor8918]

Yes, you will want to run a gauge 4 or 6 wire from the alternator to either the battery directly or to the distribution block (the latter is where I connected my power wire). The signal wire size can be the same size, 16-18 gauge. Just need a larger power wire because the output is like twice the number of amps over stock.

[@TS-gw1kz]

any trouble after taking that factory voltage regulator out? I'm getting ready to attempt this swap and it just seems weird throwing it out

[@roberttaylor8918]

It's been the best thing ever! Truck starts every day (even after sitting for a month), I drove my truck to Yakima, WA with a car trailer (with trailer lights) it took 20 hours one way a few months ago and I still dont have any issues. Best thing is to ditch that factory unit as soon as you can.

[@tylerjay5054]

Thinking about doing this with my 90 7.3 Turbo thinking there's something wrong as the gauges have started acting up and flipping around in the lights go dim and bright

[@roberttaylor8918]

I would first look at the battery (+-) cables for corrosion and replace them. Yeah, the alternator could be starting to take a die. I found with owning several of these trucks that the alternators tend to be where my electrical issues are.

[@toniecastillo4116]

I am doing this to my truck I got almost everything but in the middle of Maxie fuse I see a black fuse the one I got doesn’t have it can you please let me know what it is so I can buy it

[@roberttaylor8918]

Tonie Castillo do you mean the Mega fuse from the alternator to the power terminal? Here is what I would buy. You only need a 175 amp fuse. Alternator max output is 169 amps. www.amazon.com/Littelfuse-MEG175XP-Slo-Blo-Automotive-Bolt-Down/dp/B0002JMLJC

[@drob2959]

I know this is a old video but do you still know the actual part# for the alternator they keep showing me a different one then what you have there

[@roberttaylor8918]

I think a replacement alternator would be BOSCH AL7526N. Cross-reference this with a 1993 Ford 7.3 Diesel Ambulance package. 130 amp alternator is what you're looking for.

[@brandonlopez3217]

Use an alternator from a 90-95 Ford Taurus with the 3.8 i was having the same issue

[@elcajoia619]

Brandon, did you have to change much on wiring and fuses

[@campervanbug7658]

Beef up all electrical grounds with heavy-duty cables all new stuff snow plow stuff or heavier

[@bigun2018]

I am getting ready to do this swap myself, I have everything figured except where to get the pigtail. you mentioned ebay, do you have a link or part # where i can order one?

[@roberttaylor8918]

Cody Pierce this is the one I found on eBay but I am sure you can find a cheaper one with more searching m.ebay.com/itm/2G-to-3G-Ford-alternator-Voltage-Regulator-Conversion-Wire-Pigtail-Harness-Plug/112290562080?hash=item1a250a0020%3Ag%3Aq84AAOSwLEtYk4-h&_trkparms=pageci%253Acbadabd2-bc0e-11e7-8aa0-74dbd1808daf%257Cparentrq%253A64449c9c15f0ab4d2c0922fcfffc0481%257Ciid%253A1

[@devinames3509]

Ware does the tach plug in to the alternator

[@roberttaylor8918]

The tach does not plug into the alternator. The wiring for the tach is in the same part of the loom as the alternator wiring.

[@bigjim686]

Have you had ant trouble with this alternator ? I see that you did this upgrade in 2017.

[@roberttaylor8918]

No, it was the best thing I did for that truck. I sold the truck not too long ago but after I did that conversion I drove that truck from the Central Valley to Northern Washington, Southern Colorado, Southern California, and Central Arizona. I never had to worry about that truck leaving me stranded again.

[@mattg7952]

I just did the upgrade today with junkyard parts. 70$ to upgrade to a 130 amp alternator.

[@robh6638]

they're not selling Parts at the same quality as Ford made them in the 80s and 90s and this is their way of getting these good reliable trucks off the roads

[@roberttaylor8918]

Petor Galore totally agree.

[@devinames3509]

Is this a large frame alternator or small frame

[@roberttaylor8918]

Devin Ames I am not 100% on this but I believe it’s a large frame alternator

[@devinames3509]

Robert Taylor ok thanks man I was just wondering I have a 1987 f250 6.9 idi the battery light won’t shut off the alternator does its job just not that well I wanna throw a 200amp in there

[@klaxogen4639]

Does anyone know what size the lower alternator bolt is?

[@roberttaylor8918]

Its the exact same bolt that held on your previous alternator.

[@evanvo209mat]

You know the size? Mine fell out and i need a new one😅

[@clayjalowy3820]

How long were yo hot leads ?

[@clayjalowy3820]

Your

[@roberttaylor8918]

@@clayjalowy3820 I think they were less than two feet.

[@Troyisbig]

Robert - thanks for the video - one question - the pulleys on the new alternator are a lot smaller - and now my belts are too loose - do you have a part number on a belt that will fit by chance?

[@roberttaylor8918]

No, but take your belt to Oriellies and have them get you a smaller one.

[@Bread996]

You can purchase the original alternator with the connections on the top. Several are available, and that wasn’t the correct unit. The truck didn’t leave the factory broke!

[@roberttaylor8918]

Bread996 ya the factory parts lasted 30 years, they were fine until they weren’t. I tried multiple times to fix my charging problems using multiple parts stores and I could not get any reliable parts!!!!! Doing this swap has been awesome, truck has never not started or stopped charging or had dimming during idle. Plus you gain like 100 extra amps!!!!Best thing I have to done to make my truck more reliable.

[@kyleshears2039]

Did the 3G upgrade affect the ability of the stock volt meter to work?

[@roberttaylor8918]

Nope, check your connections to the voltmeter.

[@mikecorleone6797]

That part number brings up a 2G alternator..

[@roberttaylor8918]

Yes, I think it might be classified as a 2G alternator.

[@tonyrosbough8665]

What year alternator do I need? My 6.9 came out of a 84 f350. I put it in a 94 f350.

[@roberttaylor8918]

92 E350 IDI : part number - 7756-3N-2G

[@madhungria]

The partnumber suggest 2g? You said the alternador is 3g. Could you clarify? Thanks