DIY guide · Moderate
How to replace an alternator or starter
Before you buy a part, test the battery. A weak battery looks like a dead starter or alternator, and an auto parts store can usually test all three for free.
- Difficulty
- Moderate
- Time in the bay
- 1.5 to 4 hours
- Best bay
- 2-post lift
- Bay cost, plus tax
- $60 to $120
This is a general guide, not a manual for your car. Your vehicle's service manual comes first, especially for torque values, fluid types and capacities. Support the car on the lift locks or jack stands before you go under it, wear eye protection, and if a step feels wrong, stop and ask us. We do not do welding, grinding or painting in the bays.
Look these up before you book
- Where the part sits (some are very buried)
- Battery negative terminal location
- Bolt torque
Tools
- Socket set and extensions
- Breaker bar
- Multimeter
- Wrench for the battery terminal
- Belt tool for the alternator
Parts and fluids
- Alternator or starter, matched to your engine
- New battery cable or terminal if corroded
There is an AutoZone nearby, and during business hours parts usually reach the shop in about 10 to 20 minutes. Forgot a filter or need a different size? Order it, keep working, and do not lose your slot.
The retailer's own vehicle picker confirms what fits your car. Always compare the part number with your old part.
Step by step
- Test firstCheck the battery, the connections and the grounds. Confirm the symptom.
- Disconnect the negative battery cableAlways, before you touch the wiring.
- Remove the belt (alternator) or reach up under the car (starter)Label every wire.
- Undo the mounting bolts and electrical connectionsSupport the part as the last bolt comes out. It is heavier than it looks.
- Fit the new partClean the mounting surface. Torque the bolts and reconnect each wire.
- Reconnect the battery and testCheck charging voltage with a multimeter, or start the car.
Mistakes to avoid
- Working without disconnecting the battery
- Replacing a part when the battery was the problem
- Crossing wires on the new part
Stop and ask for help if
- If the part is buried under the intake manifold or deep in the engine bay, ask us whether the job fits your time.
Doing it in our bays
A starter is usually reached from below, so use a lift. Many alternators are reached from above, so the floor bay may be enough.
Every bay has air, power, work lights and jack stands, and the lift bays come with a short safety walkthrough. Bring your own hand tools, parts and fluids. New to lifts? Read how your first visit goes.
Questions
How do I tell the battery from the alternator?
A good battery that dies after a drive points to the alternator. A car that clicks but will not crank often points to the battery, the starter or a connection. Test before you replace.