Is your car's starter motor sluggish, clicking, or not working at all? Before you rush out to buy a expensive rebuilt starter, the issue might be a simple and inexpensive fix: worn-out carbon brushes.
Replacing the brushes inside the starter solenoid is a classic DIY repair that can save you hundreds of dollars. This guide will walk you through the entire process, from diagnosis to reassembly.
🛠️ Tools and Materials You'll Need
- New Brushes: The most important part! You'll need a brush kit specific to your car's starter motor model. These are often sold with a new spring and plate.
- Socket Set and Wrenches: Standard and deep-well sockets, especially in the common sizes for your vehicle (e.g., 8mm, 10mm, 13mm, 15mm).
- Screwdrivers: Both flathead and Phillips head.
- Needle-Nose Pliers: For handling small clips and springs.
- Multimeter: For testing continuity and diagnosing electrical issues.
- Safety Glasses and Gloves: Always protect your eyes and hands.
- Wire Brush: For cleaning connections and components.
- Electrical Contact Cleaner: To clean the commutator.
- Dielectric Grease: For reassembly (optional but recommended).
⚠️ Safety First!
- Disconnect the Battery! This is non-negotiable. Disconnect the negative terminal of your car battery before touching the starter. The starter is connected directly to the battery and can cause severe sparks or shocks if shorted.
- Work on a Clean, Stable Surface. A clean workbench is ideal for disassembling the starter.
- Take Pictures. As you disassemble the starter, take photos at each step. This will be your map for reassembly.
🔧 Step-by-Step Guide
Step 1: Remove the Starter Motor
- Locate the starter motor on your vehicle. It's typically mounted on the lower part of the engine, where the engine and transmission meet.
- Identify the electrical connections: the large main power cable from the battery and the smaller solenoid trigger wire.
- Using the appropriate socket, carefully remove these nuts and disconnect the wires.
- Unbolt the starter from its mounting points (usually 2 or 3 bolts). The starter may be heavy, so support it as you remove the last bolt.
- Carefully maneuver the starter out from the engine bay.
Step 2: Disassemble the Starter
Starter designs vary, but the general process is similar.
- Identify the Solenoid: The smaller cylinder attached to the main motor body. It often has two or three large bolts holding it on.
- Remove the Solenoid: Unscrew the bolts connecting the solenoid to the motor. You may need to gently pry it off. Be careful—there is often a plunger and a spring inside that can pop out.
- Open the Motor Case: Look for long through-bolts running the length of the starter's main housing. Remove these bolts. The housing should then separate, revealing the armature (the central spinning part) and the brush assembly.
![Starter disassembly diagram showing the armature, field coils, and brush holder]
The brush holder is usually located at the end of the motor opposite the drive gear.
Step 3: Identify and Replace the Brushes
- Locate the Brush Holder: This is a plastic or Bakelite plate that holds the four (or sometimes two) carbon brushes and their springs.
- Inspect the Brushes: The new brushes will be long (e.g., 12-15mm). Your old ones are likely worn down to a nub (less than 5mm). This is your confirmation that they needed replacement.
- Inspect the Commutator: This is the copper-colored segmented surface on the end of the armature. It should be clean and smooth, not burnt, pitted, or gouged. Lightly clean it with electrical contact cleaner and a wire brush if needed. Do not sand it aggressively.
- Replace the Brushes: The method depends on your brush holder design.
- Clip-in Brushes: These simply unclip from the holder. Press the spring down, slide the old brush out, and slide the new one in.
- Soldered Brushes (Less Common): You will need to carefully desolder the old brush wire from the field terminal and solder the new one in place. Use a high-wattage iron and be quick to avoid damaging the holder.
![Comparison of a new brush next to a severely worn-down brush]
The difference in length is often dramatic.
Step 4: Reassemble the Starter
This is the reverse of disassembly, but with extra care.
- Install the Brush Holder: Getting the new, longer brushes to fit over the commutator can be tricky. The best method is to lift the brushes and slide a thin zip tie or wire under each spring to hold them in the retracted position. Place the holder over the commutator, seat it properly, and then pull the zip ties out, allowing the springs to push the brushes onto the commutator.
- Rejoin the Motor Halves: Carefully place the other half of the motor housing back on, ensuring everything aligns. Reinstall and tighten the long through-bolts evenly.
- Reattach the Solenoid: Don't forget the plunger and spring inside! Ensure the plunger engages correctly with the drive gear mechanism.
- Apply Dielectric Grease: A small dab on the electrical terminals and the solenoid plunger can prevent corrosion and ensure smooth operation.
Step 5: Reinstall and Test
- Maneuver the rebuilt starter back into position.
- Reconnect the main power cable and the trigger wire. Ensure the connections are clean and tight.
- Bolt the starter firmly to its mounting points.
- Reconnect the negative battery terminal.
- Get in the car, turn the key, and enjoy the satisfying sound of a perfectly functioning starter!
🤔 When to Call a Professional
- If the commutator is deeply scored or damaged.
- If the armature or field coils are visibly burnt or smell burnt. A multimeter test for shorts or opens is a good idea if you suspect this.
- If the starter drive gear is damaged and doesn't engage properly.
- If you simply don't feel comfortable with the electrical and mechanical disassembly.
💡 Conclusion
Replacing starter motor brushes is a highly rewarding DIY job. It requires patience and attention to detail, but the cost savings are immense. Instead of paying R2000-R6000 for a new starter and installation, you can often fix the problem yourself for under R500 with a brush kit and an afternoon of your time. It’s a fantastic way to keep an older car on the road and gain a deeper understanding of how your vehicle works.