Bullnose Bill Answer
by Ed

Can you guide me on installing a 3G alternator in my 1985 F-150 that currently has a 2G alternator? Where can I source one?

Bullnose Bill explaining 3G alternator installation for a 1985 F-150.

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Bill says:

Hey there! It’s fantastic to hear you’re diving into the upgrade of your 1985 F-150—going from that old 2G alternator to a 3G is a great choice! You’ll boost your truck’s electrical system, and it’s not too tough to install. So, let’s break it down step by step!

Finding a 3G Alternator

You have a couple of options when it comes to sourcing a 3G alternator.

  1. New Alternator: This is the way to go if you want reliability and warranty. You can find them at most auto parts stores, or check online retailers like RockAuto, Summit Racing, or even Amazon. Make sure you get a 130-amp model for optimal performance.

  2. Junkyard: If you’re looking to save some bucks and enjoy a bit of the thrill of the hunt, check your local junkyard. Just be sure to inspect it carefully for any signs of damage or wear. Sometimes, you can find gems there!

Installation Steps

Here’s a quick rundown on how to install the 3G alternator:

  1. Disconnect the Battery: Safety first! Always disconnect your battery before working on electrical components.

  2. Remove the Old 2G Alternator:

    • Remove the wiring harness from the 2G alternator. You’ll have a couple of connectors to detach.
    • Take off the belt by loosening the tensioner and sliding it off the alternator.
    • Unbolt the alternator from its bracket and remove it.

  3. Get the Right Bracket:

    • The good news is that the 3G alternator often fits right in the original location. However, sometimes you might need a new bracket. There are kits available specifically for swapping to a 3G alternator. You can find these at auto parts stores or online.

  4. Install the New 3G Alternator:

    • Place the 3G alternator in the bracket and bolt it down.
    • Reattach the wiring:
      • Connect the main power wire (usually a large ring terminal) to the B+ terminal.
      • Connect the smaller plug (the stator wire) to the corresponding terminal.
    • If your 3G alternator has an "I" terminal, you may need to run a wire to the ignition switch for proper charging—this is where the fun of learning comes in!

  5. Reattach the Belt: Put the serpentine belt back on and ensure it’s aligned correctly on all pulleys.

  6. Reconnect the Battery: Now that everything is in place, reconnect your battery.

  7. Test It Out: Start your truck and check the voltage at the battery with a multimeter. You should see a solid 13.5 to 14.5 volts while the engine is running.

Additional Tips

  • Wiring Considerations: Sometimes, you might need to modify your wiring a bit; be prepared for that. A wiring diagram can be a lifesaver if you’re unsure.
  • Pulley Compatibility: The 3G alternator may have a different pulley than the 2G. Check that they match up, or you may need to swap pulleys.

Community Resources

As you tackle this project, I recommend checking out the Bullnose Garage YouTube channel for visual guidance! They have some fantastic content that can help you see the process in action.

If you’re looking for further advice or have more questions, feel free to ask! And don’t forget to check out the Bullnose Ford subreddit at reddit.com/r/bullnoseford for some extra community support and tips! Happy wrenching!

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User:

Which vehicles should I search for in a junkyard to find a 3G alternator?

Bill avatar
Bill:

Great question! If you’re on the hunt for a 3G alternator in a junkyard, you’re looking for specific Ford models from the mid-1990s to early 2000s. Here’s a handy list of vehicles to check out:

Vehicles to Look For:

  1. 1994-2002 Ford F-Series Trucks: This includes the F-150, F-250, and F-350 models. Most will have the 3G alternator.

  2. 1994-2001 Ford Explorer: The early Explorers also commonly featured the 3G alternator.

  3. 1995-2001 Ford Mustang: You might find a 3G in these sporty rides as well.

  4. 1994-1997 Ford Bronco: These classic SUVs are worth a look too.

  5. 1994-1998 Ford Ranger: The smaller Ranger trucks often have the 3G as well.

Quick Tip for Identification:

When you’re scavenging at the junkyard, look for alternators that have the following specifications:

  • A round, clock-style face.
  • The 3G alternator typically has a larger diameter than the 2G and has a single wire connector along with a larger B+ terminal.

If you’re unsure, you can always take a picture of your existing 2G alternator and compare it with what you find. Remember, while you’re at it, check the condition of the alternator as well—look for signs of wear, corrosion, or damage.

Happy hunting, and feel free to ask if you have more questions!

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User:

Is it necessary to upgrade my battery wiring and ground when installing the 3G alternator? What is the typical amperage and wire size for a 3G?

Bill avatar
Bill:

Absolutely, upgrading your battery wiring and ground is a smart move, especially when you’re swapping in a 3G alternator! A solid electrical system is crucial for ensuring that everything runs smoothly and efficiently, and upgrading those wires can help handle the increased output of the 3G.

Typical Amperage of a 3G Alternator

The 3G alternator typically comes in 130 amps, and some can even push up to 150 amps. This gives you plenty of extra power for accessories, lights, and anything else you might add down the road.

Recommended Wire Sizes

When upgrading your wiring to accommodate the 3G alternator, here are some guidelines:

  1. Battery to Alternator Wire:

    • Wire Size: Use 4 AWG wire. This size will handle the amperage without overheating and ensure efficient charging.
    • Make sure you use high-quality welding cable or battery cable, as they are designed to handle high current.

  2. Ground Wire:

    • Wire Size: Also use 4 AWG wire for the ground; a solid ground is crucial for your alternator and entire electrical system.
    • It’s a good practice to connect the ground directly to the engine block or chassis to minimize resistance.

  3. Battery to Chassis Ground:

    • If you haven’t upgraded this already, consider adding a dedicated grounding strap or wire from the battery to the chassis using 4 AWG as well.

Additional Tips

  • Connector Quality: Use high-quality terminals and connectors to ensure good contact and prevent corrosion.
  • Fuse: Consider adding an inline fuse on the battery wire to protect against electrical shorts. A 175-amp fuse is a good choice for a 3G setup.
  • Routing: Route your wires carefully to avoid chafing against sharp edges or hot components.

Upgrading your battery and ground wiring alongside the alternator swap will help ensure your electrical system is robust and reliable. Plus, who doesn’t love a little extra peace of mind while they’re cruising in their trusty Bullnose?

If you have any more questions or need tips on anything else, just let me know! Happy wrenching!

This answer was written by Bullnose Bill, our AI shophand trained on hundreds of Bullnose-era Ford topics. He knows his way around old Ford Trucks.

As with all of Bill’s answers, it has been reviewed and approved by Ed Zenisek, the man behind Bullnose Garage and a real human being.

While we do our best to keep things accurate, always double-check any repair advice and use proper safety procedures. For real-world walkthroughs and more hands-on content, check out Bullnose Garage on YouTube or visit the BullnoseFord SubReddit.

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