Warning: Undefined array key "HTTP_REFERER" in /home/sprayersandparts.com/public_html/fmeosconfig.php on line 111 Graco Carbon Brushes: When & How to Replace Them
Replace Graco carbon brushes when you see sparks through the motor vents, the motor runs slower than normal, or the machine cuts out under load. Always replace both brushes as a pair — never just one. The job takes about 15–30 minutes, requires no special tools beyond a flat-head screwdriver, and the brushes are inexpensive. Brush replacement is the most cost-effective motor service you can do. Call us at 713-931-4102 with your model number for the correct brush set.
Carbon brushes are small rectangular blocks of compressed carbon-graphite that conduct electricity between the stationary power supply and the rotating armature (commutator) inside the motor. They physically press against the spinning commutator and transfer current through direct contact.
Because they work by friction and direct contact, they are designed to wear down gradually over time — they are a sacrificial part. When they wear down too far, the motor loses power, runs rough, sparks excessively, or stops working altogether. The good news: replacing carbon brushes is one of the easiest and cheapest motor repairs possible, and it can bring a motor back to full power in under 30 minutes.
2. Signs You Need New Carbon Brushes
Visible Sparking
Sparks visible through motor vent slots during operation. Some sparking is normal on startup — continuous or large sparks indicate worn brushes.
Slower Motor Speed
Machine sounds and feels like it's running slower than usual. Pump output drops even though spray tip and packings are fine.
Cutting Out Under Load
Machine runs fine at low pressure but cuts out when you pull the trigger at working pressure. Intermittent power loss during spraying.
Pressure Fluctuation
Spray pressure surges and drops during use. Motor speed inconsistency caused by poor brush contact translates directly to pump pressure variation.
Motor Running Hot
Motor feels unusually hot to the touch after normal use. Arcing from worn brushes generates heat that affects motor temperature.
Unusual Motor Noise
Grinding, rattling, or rough sound from the motor area. Worn brushes can chatter against the commutator rather than sliding smoothly.
Do not ignore continuous sparking. Prolonged operation with severely worn brushes can damage the commutator surface, turning a $15 brush replacement into a $200+ armature replacement. When you see sustained sparking, stop work and replace brushes that day.
3. Carbon Brush Part Numbers by Graco Model
Graco Model
Brush Part #
Notes
Graco 390 PC / 390 Hi-Boy
CB-390-PR
Sold as a pair — always replace both
Graco 395 PC
CB-395-PR
Confirm with serial number suffix
Graco 490 PC / 495 PC
CB-490-PR
Sold as a pair
Graco Magnum X5
CB-X5-PR
Smaller brush — X5 specific
Graco Magnum X7
CB-X7-PR
Confirm with serial number
Graco Magnum ProX17
CB-PX17-PR
Sold as a pair
Graco Ultra 395 / 495
CB-U395-PR
Electronic control model variant
Graco Mark V
CB-MKV-PR
Heavier duty brush — confirm model
The part numbers above are our internal stock references. Always call us at 713-931-4102 with your model AND serial number to confirm the correct brush set — multiple brush lengths were used across production runs of the same model.
Disconnect from power completely before starting. Do not just switch off the machine — unplug the power cord from the outlet. Carbon brush access requires working near the motor, and electrical shock is a real risk on a plugged-in machine.
1
Disconnect Power
Unplug the sprayer from the power outlet completely. Turn off the machine at its switch. Allow the motor to cool fully if it has been running — approximately 10 minutes.
⏱ ~1 min + cooling time
2
Locate the Brush Access Caps
On most Graco sprayers, the two brush access caps are located on opposite sides of the motor housing — they appear as round plastic or metal caps with a flat-head slot. On some models they are covered by a plastic cover that snaps off. Consult your manual if you can't locate them — or call us.
⏱ ~2 min
3
Remove the Brush Caps
Insert a flat-head screwdriver into the cap slot and turn counterclockwise to unscrew. The cap and spring assembly will become accessible. On some models the spring pressure may push the cap slightly when unscrewed — hold it firmly while removing.
⏱ ~3 min
4
Remove Old Brushes & Inspect
Pull the brush and spring assembly straight out. Note the orientation of the lead wire and the direction the brush faces — it must go back in the same way. Measure the old brush length — if shorter than 1/4 inch (6mm), it was overdue for replacement. Inspect the commutator surface visible in the bore: it should be smooth and copper-coloured. Dark grooves indicate commutator wear.
⏱ ~5 min
5
Clean the Brush Bore
Use a dry lint-free cloth or brief burst of compressed air to clean carbon dust from the brush bore and visible commutator surface. Do not use solvents — they can damage insulation and commutator coatings.
⏱ ~3 min
6
Install New Brushes
Insert the new brush assembly in the same orientation as the old one — lead wire position is critical. Push the brush in gently until the spring engages and seats. The brush should slide freely in the bore without side play. Repeat for the second brush on the opposite side of the motor.
⏱ ~5 min
7
Reinstall Caps & Test
Screw brush caps back in clockwise — finger tight is sufficient. Do not overtighten. Reconnect power. Run the machine at low pressure for 2–3 minutes to seat the new brushes. Some additional sparking in the first few minutes is normal as the brushes bed in to the commutator surface.
⏱ ~5 min
6. Pro Tips for Carbon Brush Life
Inspect annually on commercial machines: Pull the brush caps once a year and measure brush length. Replace before failure — don't wait for the sparking symptom.
Always replace as a pair: One new brush next to one worn brush creates uneven armature contact, overloads the new brush, and causes rapid failure of both.
Check your power supply: Voltage fluctuations and undersized extension cords cause motors to draw higher current, overheating brushes. Use a heavy-duty 12-gauge extension cord of 50 feet or less.
Don't run the motor dry: Running the sprayer without paint or solvent in the pump puts the motor under maximum load for extended periods, overheating brushes faster.
Clean commutator if grooved: Light commutator scoring can be polished with 400-grit sandpaper while the motor spins slowly — but this requires experience. Contact us if you're not confident doing this yourself.
Shop Graco Carbon Brush Sets
All models in stock. Sold as pairs. Ships same day. Call with your model number for the correct set.
Key signs: sparks visible through motor vents during operation, motor running slower than normal, machine cutting out under load, pressure fluctuating during spraying, or the motor sounding rough or grinding. If you see continuous sparking (not just a brief flash on startup), inspect brushes immediately — continued use risks commutator damage.
On heavy commercial use (5 days a week, 8 hours a day), expect 12–18 months. On moderate contractor use, 2–3 years is typical. Homeowner machines used occasionally may see brushes last 4–6 years. Inspect annually on commercial machines rather than waiting for failure symptoms.
Yes — always replace both as a set. Both brushes wear at approximately the same rate. Installing one new brush alongside a worn one creates uneven contact, overloads the new brush, and can damage the commutator. All our brush sets are sold in pairs for this reason.
Yes — it's one of the easiest motor repairs on any power tool. All you need is a flat-head screwdriver and needle-nose pliers. The whole job takes 15–30 minutes. The critical safety requirement is disconnecting power completely before starting. Call us at 713-931-4102 if you want to be walked through it live.
Light sparking during the first 10–15 minutes of operation with new brushes is normal — this is the brushes bedding into the commutator surface. If sparking is heavy and continuous after 20 minutes of use, check that the brushes are correctly oriented (lead wire position) and fully seated. Heavy sustained sparking after bedding-in may indicate commutator wear or a brush that is sticking in the bore.
Pro tip: Carbon brush replacement is a 20-minute job. If you see sparking through the vent slots, stop using the machine immediately — a seized commutator is a $500+ repair vs. $25 for fresh brushes.
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