Is replacing an alternator a big job?

For most cars, replacing an alternator is a manageable, mid-level repair that a capable DIYer can tackle in a few hours, or a shop can complete in about an hour or two depending on access. In cramped engine bays or on newer vehicles with smart charging systems, it can take longer. If you’re not confident around electrical systems, hiring a professional is a prudent option.

What makes it easy or hard

Several design and accessibility factors determine how difficult the replacement will be. Here are the most important considerations before you start.

• Engine layout and alternator location (frontal vs. rear-mounted, tight spaces, or obstructions)


• Belt routing and tensioning setup (single serpentine belt vs. multiple belts)


• Accessibility of mounting bolts and electrical connections


• Presence of ancillary components on the same bracket (power steering pump, AC compressor)


• Age and corrosion of bolts and connections, which can affect removal/reattachment

The bottom line: the easier the engine bay access and belt system, the faster and simpler the job. Complex layouts, tight spaces, or stubborn fasteners raise time and difficulty.

Vehicle-specific considerations

Some makes and models place the alternator in particularly awkward spots or share mounting with other components. For example, trucks with large engines or hybrids may require additional steps or special tools. Always consult your vehicle’s service manual for model-specific guidance and torque specs.

Tools and parts you’ll likely need

Having the right tools and a new alternator ready helps the replacement go smoothly and reduces the risk of damage to the belt or electrical circuits.

• New alternator compatible with your vehicle


• Representative serpentine belt or belt routing diagram, if a belt is worn


• Socket set with ratchets and extensions (often 10mm–14mm bolts, sometimes larger)


• Wrench set (including a breaker bar for high-torque mounts)


• Belt tensioner tool or an appropriate method to relieve tension on the belt


• Electrical contact cleaner and dielectric grease


• Safety gear: gloves and eye protection


• Battery terminal puller or spare clamps, if needed


• Torque wrench (to spec for mounting bolts, if your manual requires)

With the right tools and a replacement alternator, you’ll minimize surprises and keep the replacement efficient and safe.

Step-by-step: replacing the alternator

Here is a general workflow that applies to many vehicles. Always consult your specific service manual for torque specs and sequence, as details vary by make and model.

1. Disconnect the negative battery cable and move the terminal away from the battery to prevent electrical shorts.


2. Locate the alternator, note belt routing, and release tension on the serpentine belt using the tensioner tool or appropriate method; remove the belt from the alternator pulley.


3. Disconnect the wiring harness and any ground wires from the alternator.


4. Unbolt the alternator mounting bolts and remove the unit from the engine bay.


5. Install the new alternator, attach mounting bolts, and torque to spec; reconnect electrical connections and ground.


6. Reinstall the serpentine belt, ensure it sits correctly on all pulleys, and apply belt tension per your manual.


7. Reconnect the negative battery terminal, start the engine, and check the charging voltage (roughly 13.8–14.8 volts when running) and watch for abnormal noises or smells.

If the belt or idler pulley shows wear, replace them as part of the job to prevent future belt failure. For some vehicles, the alternator may be integrated with other accessories, or the route may require additional removal work.

What to expect in terms of time and cost

Time and cost vary by vehicle and shop. DIYers typically spend 1–3 hours for the replacement, depending on access and whether any ancillary components must be removed. Shops usually bill for labor in the 1–2 hour range, plus the price of the alternator. More complex or specialty vehicles can take longer.

Summary

Replacing an alternator is generally a mid-level repair rather than a huge project. For cars with straightforward engine bays, a capable DIYer can complete it in a few hours; many vehicles at a repair shop can be done in under a couple of hours. Complex layouts, tight spaces, or components that share mounting hardware can increase difficulty and time. With careful planning, the right tools, and a compatible replacement part, most drivers can handle the job, though seeking professional help is sensible for uncertain situations.

Can I drive 20 miles with a bad alternator?

If the alternator is dead, 20 miles would be pushing it even with a healthy battery that was fully charged. You'd probably stall out before making it home, but it might be possible.

How much should it cost to replace an alternator?

Replacing an alternator typically costs between $350 and $900, but can be higher depending on the vehicle, with the average falling between $500 and $1,000. The price is a combination of parts, which can range from about $100 to $500, and labor, which is often a few hours. Factors like the car's make and model, the alternator's location, and the type of part (new, rebuilt, or OEM) all influence the final cost. 
Cost breakdown

Component	Typical Cost Range
Alternator Part	$100 to $500 (or more for luxury/specialty vehicles)
Labor	$150 to $500 (depending on labor rates and complexity)
Total	$350 to $900+

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Factors that affect the total cost

• Vehicle make and model: Luxury vehicles or those with specialty parts can have much higher costs for both the part and labor. For example, some high-end models may require alternators in the $500 to $700 range, or even higher. 
• Alternator placement: An alternator that is easily accessible in the engine bay will cost less to replace than one buried deep inside the engine, which requires more labor to reach. 
• Type of part:
  • Rebuilt/Remanufactured: Often cheaper than new and can be a good way to save money, especially if you are doing the labor yourself. However, ensure it comes with a good warranty. 
  • New OEM: The most expensive option, but offers the highest quality and is often the only choice for newer vehicles still under warranty. 
• Serpentine belt: If the serpentine belt (sometimes called the alternator belt) needs to be replaced, expect to add an extra $20 to $50 to the bill. 

Is replacing an alternator an easy job?

Replacing an alternator can range from easy to challenging depending on the vehicle's make and model. The process itself is straightforward—involving unbolting the old unit and installing the new one—but accessibility is the main difficulty, as modern cars often have alternators buried deep in the engine compartment, requiring other parts to be removed first. For a beginner, the job is achievable with basic tools and patience, potentially taking 1-2 hours or longer. 
This video demonstrates the process of replacing an alternator: 56sAutoZoneYouTube · Sep 28, 2023
What makes it easy

• Simple core task: The actual steps of removing and replacing an alternator are simple: disconnect the battery, remove the accessory belt, unbolt the alternator, disconnect electrical connectors, and then reverse the process with the new one. 
• No fluids to handle: Unlike other repairs, changing an alternator doesn't require dealing with engine oil, coolant, or other liquids, which simplifies the job. 
• Accessible in older cars: In older or simpler vehicles, the alternator is often mounted in an accessible location under the hood. 

What makes it difficult

• Poor accessibility: On many modern vehicles, the alternator is difficult to reach, requiring you to remove other components like fans, splash shields, or other parts of the engine. 
• Stubborn bolts: The bolts holding the alternator can be difficult to remove due to rust or tight spaces, sometimes requiring a breaker bar for extra leverage. 
• Specialized tools: While basic tools are often enough, some jobs may require a belt tensioner tool or a swivel joint for better access. 

You can watch this video to see an example of how to remove the belt tensioner: 1mApple Valley FarmYouTube · Aug 5, 2024
Before you begin

• Check the battery: If the car still starts, the issue might be a bad connection or a worn-out belt rather than the alternator itself. 
• Disconnect the battery: Always disconnect the negative terminal of the battery first to prevent short circuits and electric shocks. 
• Consult a guide: Before starting, find a video or guide specific to your car's make and model to understand how to access the alternator and what other parts may need to be removed. 

Is a new alternator a big job?

Changing an alternator is a moderately challenging DIY job for someone with basic mechanical skills and the right tools. Difficulty depends on vehicle make/model, engine layout, and whether the alternator is easily accessible.