Do You Have to Replace the Motor If the Motor Carbon Brush Is Broken?

[DeJack]

If the motor carbon brush is damaged, there is no need to replace the entire motor; simply replacing the carbon brush is sufficient. To replace the carbon brush, first disassemble the power drill, then remove the brush holder inside the drill. Next, open the back cover of the removed brush holder, take out the old carbon brush, and install the new one. Finally, reattach the back cover to complete the carbon brush replacement. Symptoms of a Damaged Motor Carbon Brush: If the starter carbon brush is damaged, the motor of the starter will fail to rotate. Specific symptoms include hearing a slow and weak starting sound, difficulty in starting the engine, or even complete failure to start. In such cases, the starter carbon brush must be replaced. Precautions for Replacing Motor Carbon Brushes: During replacement, ensure that clothing and cuffs are securely fastened to avoid entanglement with moving parts; stand on an insulated mat; never touch both poles simultaneously or one pole to the ground; use the same model of carbon brush for the same unit. Functional Characteristics of Motor Carbon Brushes: The primary function of the carbon brush is to conduct electricity while rubbing against metal, differing from metal-to-metal friction conduction. In metal-to-metal friction conduction, friction may increase, and the contact area might fuse together. However, this does not happen with carbon brushes, as carbon and metal are different elements.

[LeWilliam]

I've repaired quite a few electric motor failures, and carbon brush issues are actually quite common. If it's just worn-out carbon brushes, simply disassemble and replace them with new ones - there's no need to replace the entire motor, saving both time and money. However, it's important to note that if the old carbon brush fragments have scratched grooves into the commutator, or if there are signs of burnt motor windings, then a complete replacement should indeed be considered. Last time when I helped my neighbor repair a power window motor, I found abnormal noises persisted after replacing the brushes. Upon disassembly, I discovered the rotor shaft was worn out - in such cases, a complete assembly replacement is truly necessary. By the way, frequent carbon brush burnout might be caused by voltage instability or excessive load, so it's advisable to check the power supply circuit.

[OHailey]

The approach to dealing with motor brush failure depends on the situation. For devices like electric drills or power window motors, replacing the brushes can be done for just a few dozen dollars, and it's simple enough to DIY: remove the casing, take out the old brushes, clean the carbon dust, and install the new brushes. However, for car starter motors, it's not advisable to attempt repairs yourself. Not only are they installed in hard-to-reach places, but if not reassembled properly, it could lead to starting failures. I've experienced this twice—after helping a friend replace the starter motor brushes, their car suddenly wouldn't start halfway down the road, and the towing fee ended up costing more than the repair. In reality, brush lifespan is related to driving habits; cars that frequently start and stop in traffic jams will wear out brushes faster.

[OXavier]

When I first started learning auto repair, my mentor taught us not to rush into replacing the entire starter assembly when it malfunctions. Carbon brushes, as wear-prone components, are normal to replace after wear, just like changing brake pads. I usually use a multimeter to check the coil resistance first. If the coil is fine and only the carbon brushes are damaged, replacing just the parts can save 80-90% of the cost. However, for water-damaged vehicles or old cars with over 200,000 kilometers, where the brush holder is rusted and stuck or the commutator is worn concave, it's more practical to replace the entire motor rather than force a repair. By the way, some car motors require specific carbon brush models – using the wrong type can cause arcing and burn the commutator.