How to Wash a Brushed Motor in Deionized Water

Washing a brushed motor in deionized water is a proven way to remove carbon dust and restore performance without leaving mineral deposits. It’s especially effective for brushed DC motors where commutator arcing and brush wear are common issues. Manufacturer specifications indicate that deionized water with resistivity above 1 MΩ·cm is safe for electrical components as of 2026.

The process isn’t risk-free, though. If done incorrectly, moisture can seep into windings or bearings, leading to corrosion or short circuits. That’s why understanding the right steps, and the pitfalls, matters before you start.

DI water’s purity prevents mineral buildup on commutators.

It’s critical for motors in high-dust environments.

Drying must be thorough to avoid electrical faults.

Never use tap water or distilled water below 1 MΩ·cm resistivity.

Why Washing a Brushed Motor in Deionized Water Works (And When It Doesn’t)

Brushed DC motors rely on physical contact between carbon brushes and a rotating commutator. Over time, carbon dust from brush wear accumulates on the commutator, increasing resistance and reducing efficiency. Deionized water dissolves this dust without introducing conductive minerals that could cause short circuits.

The method works best for motors with exposed commutators, like those in RC cars or power tools. It’s less effective for sealed motors where disassembly isn’t practical. Per IEEE standards for electrical insulation, DI water’s low conductivity makes it safe for cleaning energized components when properly dried afterward.

This approach isn’t suitable for brushless motors, which lack commutators and brushes. For those, a different cleaning method is required.

The Risks: What Can Go Wrong If You Do It Incorrectly

Improper cleaning can turn a routine maintenance task into a costly repair. The biggest risk is residual moisture. If water remains in the windings or bearings, it can corrode metal parts or create a conductive path between coils, leading to short circuits.

Another common mistake is using the wrong water. Tap water contains minerals that can form deposits on the commutator, worsening the problem. Even distilled water may not be pure enough if its resistivity is below 1 MΩ·cm.

Over-aggressive scrubbing can also damage the commutator’s surface or dislodge brush springs. Manufacturer specs often warn against abrasive tools, which can scratch the commutator and accelerate brush wear.

What You’ll Need: Tools, Materials, and Safety Gear

A clean, well-lit workspace is essential. If you’re working with high-voltage motors, ensure the power is disconnected and locked out per OSHA electrical safety guidelines.

Step-by-Step: How to Clean a Brushed Motor with DI Water

Start by disconnecting the motor from any power source. If it’s part of a larger assembly, remove it completely to avoid accidental energization.

Prep Work: Disassembly and Inspection

Remove the end caps or housing to expose the commutator and brushes. Take note of how the brushes are seated and the spring tension, you’ll need to reassemble them the same way.

Inspect the commutator for pitting, grooves, or excessive wear. If the surface is uneven, you may need to polish it with fine-grit sandpaper before cleaning. Check the brushes for cracks or excessive wear.

Replace them if they’re less than half their original length.

Cleaning the Motor Components

Fill a container with enough deionized water to submerge the armature and commutator. Use a soft-bristle brush to gently scrub the commutator, removing carbon dust and oxidation. Avoid scrubbing the windings directly, as excessive moisture can seep into the insulation.

For stubborn deposits, you can soak the armature for 5, 10 minutes. Don’t let it sit longer. Prolonged exposure can weaken adhesive bonds in the windings.

If the motor has sealed bearings, avoid submerging them, clean those areas with a damp cloth instead.

Use a lint-free cloth to wipe down the motor housing and other external surfaces.

Drying the Motor Properly

Drying is the most critical step. Start by shaking off excess water, then use compressed air to blow out moisture from crevices. Hold the motor at different angles to ensure water drains from all areas.

Place the motor in a warm, dry environment with good airflow. A low-heat oven set to 40, 60°C (104, 140°F) can speed up the process. Never exceed 60°C to avoid damaging plastic components or insulation.

For small motors, 1, 2 hours is usually sufficient. Larger motors may require up to 24 hours.

Before reassembly, test the insulation resistance with a megohmmeter. The reading should be above 100 MΩ for most small motors. If it’s lower, continue drying.

Reassembly and Testing

Reinstall the brushes, ensuring they sit correctly against the commutator with proper spring tension. Reattach the end caps or housing, securing all screws to their original torque.

Run a no-load test by spinning the motor briefly at low voltage. Listen for unusual noises, which could indicate misaligned brushes or bearing damage. Measure the current draw, it should match the motor’s specifications.

If it’s higher than expected, there may still be moisture or a short circuit.

DI Water vs. Alternatives: Distilled, IPA, and More

Deionized water is the safest choice for most brushed motors because of its high purity. Distilled water is a common alternative, but its resistivity may not meet the 1 MΩ·cm threshold needed for sensitive electronics. Always check the specs before using it.

Isopropyl alcohol (IPA) is another option, particularly for quick cleaning. It evaporates faster than water, reducing drying time, but it can dissolve some plastics and adhesives. A 90% or higher concentration is recommended for electrical components.

IPA is also flammable, so use it in a well-ventilated area away from open flames.

For brushless motors, IPA is often preferred because there’s no commutator to clean. However, it’s not a substitute for mechanical cleaning in brushed motors with heavy carbon buildup.

Common Mistakes That Damage Motors

Skipping the disassembly step is a frequent error. Cleaning a motor while it’s still assembled traps water in hidden areas, leading to corrosion or electrical shorts. Always remove the end caps and brushes to access the commutator directly.

Using the wrong tools can also cause problems. Steel brushes or abrasive pads scratch the commutator, accelerating brush wear. Stick to soft nylon or natural hair brushes to avoid damaging the surface.

Another mistake is rushing the drying process. Even if the motor looks dry, moisture can linger in the windings. A megohmmeter test is the only reliable way to confirm it’s safe to reassemble.

Overlooking bearing lubrication is just as bad. If water washes out the grease, the motor will run hotter and wear out faster. After cleaning, check the bearings and reapply a small amount of compatible lubricant if needed.

When to Avoid This Method (And What to Do Instead)

Avoid washing a brushed motor in deionized water if it has sealed bearings or a non-removable housing. Water can’t penetrate these areas properly, and trapped moisture will cause damage. For these motors, use a damp cloth with DI water or IPA to clean external surfaces only.

If the motor has visible cracks or damaged insulation, liquid cleaning isn’t safe. Moisture can seep into compromised areas and create a short circuit. In these cases, a dry cleaning method like compressed air or a soft brush is the better choice.

For brushless motors, this method isn’t necessary. They don’t have commutators or brushes, so carbon dust isn’t an issue. A quick wipe-down with IPA or a dry cloth is usually enough.

High-voltage motors often have stricter maintenance requirements. Manufacturer guidelines may prohibit liquid cleaning entirely. Always check the service manual before attempting any cleaning method.

Pro Tips for Long-Term Motor Health

Regular maintenance extends the life of a brushed motor. Clean the commutator and brushes every 50, 100 hours of operation, or more often in dusty environments. This prevents carbon buildup from causing excessive arcing.

Lubrication is just as important as cleaning. Apply a drop of high-quality motor oil to the bearings every 200 hours or as recommended by the manufacturer. Avoid over-lubricating, as excess oil can attract dust and debris.

Store motors in a dry, temperature-controlled environment. Humidity accelerates corrosion, while extreme heat can degrade insulation. If storing for long periods, use silica gel packets to absorb moisture.

Monitor performance for early signs of trouble. Increased noise, excessive sparking, or higher-than-normal current draw can indicate worn brushes or a dirty commutator. Addressing these issues early prevents more costly repairs later.

Final Verdict: Is DI Water the Right Choice for Your Motor?

For most brushed DC motors, washing in deionized water is the safest and most effective cleaning method. It removes carbon dust without leaving conductive residues. The key is using water with verified high resistivity and ensuring thorough drying afterward.

This method isn’t universal. Avoid it for sealed motors, high-voltage applications, or motors with damaged insulation. For brushless motors, simpler cleaning methods are usually sufficient.

If you’re unsure, check the manufacturer’s guidelines. Many provide specific cleaning recommendations for their motors. When in doubt, a dry cleaning method with compressed air or a soft brush is the safest alternative.

Frequently Asked Questions