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Is your Bosch drill not working? Whether your drill won't start, keeps cutting out, has lost power, the chuck isn't spinning or the motor is making unusual noises, there are several possible causes.
Bosch produces a huge range of corded and cordless drills and combi drills, from compact DIY models to professional cordless machines. Depending on the fault and the exact model, it may be possible to replace an individual component rather than replacing the entire drill.
In this guide, we'll look at the most common Bosch drill problems, what you can check and which Bosch drill parts may be needed.
If you're looking for a replacement component, you can browse our Bosch drill parts.
There are several reasons why a Bosch drill may stop working.
Common problems include:
Bosch drill won't start
Bosch drill keeps cutting out
Bosch drill has lost power
Bosch drill is sparking
Bosch drill is making a strange noise
Bosch drill chuck isn't spinning
Bosch drill chuck is slipping
Bosch cordless drill won't work
Bosch drill battery won't power the tool
Bosch drill is overheating
Bosch drill trigger isn't working
The first step is to identify exactly what happens when you try to operate the drill.
If your Bosch drill won't start at all, begin with the power supply.
If you have a cordless Bosch drill, check that the battery is:
Fully charged
Correctly fitted
Compatible with the drill
Free from obvious damage
If you have access to another compatible battery, try it in the drill.
If the drill works with another battery, the original battery may be responsible.
If the drill still doesn't work, the problem could be with the trigger, switch, motor, electronics or another internal component.
For a mains-powered Bosch drill, check:
The plug
The mains socket
The power cable
Any extension lead
The drill's switch or trigger
Never use a drill with a damaged power cable.
If the power supply is working correctly but the drill remains completely dead, an internal electrical component may have failed.
If your Bosch drill keeps cutting out, there are several possible causes.
The drill may be working under excessive load. Drilling large holes, driving long screws or working in hard materials can put considerable strain on the motor.
If you're using a cordless drill, the battery may also be struggling to provide sufficient power.
Other possible causes include:
Overheating
Worn carbon brushes
Faulty switch
Damaged motor
Internal electrical fault
Battery problem
Mechanical resistance
Allow the drill to cool if it has become hot and try again with a lighter load.
If it continues cutting out during normal use, further investigation may be required.
A Bosch drill losing power can be particularly noticeable when drilling into harder materials.
Start by checking the battery if you're using a cordless model.
An old or heavily discharged battery may not provide the same performance as a fully charged battery in good condition.
If the battery is fine, check the drill itself.
Potential causes include:
Worn carbon brushes
Armature problems
Motor faults
Damaged bearings
Mechanical resistance
Electronic faults
For a corded drill, check the power cable and mains supply before looking at internal components.
If you can see sparks coming from inside your Bosch drill, the cause could be related to the motor.
Some sparking can occur naturally in brushed motors, but excessive sparking should be investigated.
Possible causes include:
Worn carbon brushes
Damaged armature
Commutator damage
Brush holder problems
Motor faults
If the drill is producing unusually large sparks, smells of burning or has suddenly changed behaviour, stop using it.
Carbon brushes wear down through normal use.
When the brushes become worn, symptoms can include:
Intermittent operation
Loss of power
Excessive sparking
Difficulty starting
The drill stopping unexpectedly
If your Bosch drill has replaceable carbon brushes, replacing them may restore normal operation.
Always check the exact model before ordering because brush sizes and designs vary between Bosch drills.
A sudden change in the sound of your Bosch drill can indicate a mechanical problem.
Grinding, rattling, squealing or excessive whining can potentially be caused by:
Worn bearings
Damaged gears
Armature problems
Loose components
Gearbox damage
Mechanical wear
If the drill has become significantly louder than normal, don't continue using it without investigating the cause.
A relatively small component such as a bearing can sometimes be responsible for a noticeable change in noise.
If your Bosch drill chuck isn't spinning, first determine whether the motor is running.
If there's no sound or movement from the drill, the problem could involve the battery, switch, trigger, motor, brushes or electronics.
If you can hear the motor running but the chuck doesn't rotate, there could be a problem with the gearbox, gears or another part of the drive system.
This type of fault can be particularly noticeable if the drill has been subjected to heavy use or an impact.
A chuck that doesn't hold the drill bit securely can make drilling difficult and potentially dangerous.
If the chuck is slipping, check that the drill bit has been inserted correctly and that the chuck has been tightened properly.
If the bit continues to slip despite being correctly fitted, the chuck itself may be worn or damaged.
Depending on the Bosch model, a replacement chuck may be available.
When looking for a Bosch drill chuck, always check the exact model and spindle specification before ordering.
If your Bosch cordless drill is not working, check the battery before dismantling the tool.
Try the following:
Fully charge the battery.
Remove and refit the battery.
Check the battery contacts.
Try another compatible battery if available.
Check whether the charger is working correctly.
If a known-good battery doesn't make any difference, the problem may be inside the drill.
Potential faults include:
Trigger
Switch
Motor
Carbon brushes
Electronic components
Wiring
Gearbox
The trigger is one of the most frequently used components on a drill and can eventually become worn or damaged.
A faulty trigger can cause the drill to:
Not start
Stop intermittently
Run inconsistently
Require excessive pressure
Operate only in certain positions
If your trigger feels different from normal, it could be worth investigating.
Many Bosch drills use a combined electronic switch and speed-control system, so make sure you identify the correct replacement component for your model.
Many Bosch drills have a forward/reverse selector positioned around the trigger.
If the drill will only operate in one direction, or the selector no longer functions correctly, there may be a problem with the switch assembly.
Before replacing anything, check that the selector is fully engaged in either direction.
If it feels loose, damaged or doesn't operate correctly, the switch assembly may need inspecting.
It's normal for a drill to become warm during heavy use.
However, excessive heat can indicate a problem.
Possible causes include:
Overloading
Continuous heavy drilling
Blocked ventilation
Worn bearings
Motor problems
Damaged brushes
Electrical faults
If your drill becomes unusually hot, stop using it and allow it to cool.
Avoid forcing the drill through material. Selecting the correct drill bit and speed for the job can reduce the load on the motor.
If the drill continues to overheat during normal use, there may be an underlying fault.
Cordless drills and combi drills use a gearbox to provide different speeds and levels of torque.
A damaged gearbox can cause:
Grinding noises
Loss of torque
Incorrect speed
The chuck failing to rotate
Difficulty changing gears
Excessive vibration
If the drill makes a grinding noise when changing between speeds, don't force the gear selector.
Mechanical components inside the gearbox may need inspection or replacement.
If the torque adjustment on your Bosch drill doesn't seem to be working correctly, check that the collar is actually engaging with the selected setting.
If the clutch continues to slip regardless of the setting, there could be a problem with the clutch mechanism or another internal component.
This can be particularly noticeable when driving screws, where the drill may stop applying torque much earlier than expected.
If your Bosch cordless drill suddenly stops working, the battery is one of the easiest things to eliminate as a possible cause.
Check that the battery charges correctly and that the charger indicates normal charging.
If possible, test the drill with another compatible battery.
If another battery works normally, the original battery is likely to be the source of the problem.
If neither battery works, investigate the drill itself.
Depending on the model and fault, a range of Bosch drill spare parts may be available.
These can include:
Carbon brushes
Brush holders
Switches
Triggers
Chucks
Gears
Gearboxes
Bearings
Armatures
Motors
Battery terminals
Springs
Cables
Housing components
Electronic components
Screws and fasteners
You can browse our Bosch drill spare parts to find components for different Bosch drill models.
Bosch has produced a large number of drills over the years, so it's important to identify the exact model before ordering a replacement part.
Some popular Bosch drill and combi drill ranges include:
The Bosch GSB range includes many Professional cordless and corded combi drills.
When searching for replacement components, make sure you include the complete model designation, as different GSB models can use different parts.
The GSR range includes Bosch cordless drills and screwdrivers.
Again, the exact model number is important when identifying replacement components.
Bosch PSB drills are another popular range, particularly among DIY users.
Individual replacement parts may be available for specific models.
This is one of the most important steps when repairing a Bosch drill.
Don't simply search for:
Bosch drill switch
or:
Bosch drill carbon brushes
Instead, search using the complete model number.
For example:
Bosch GSB parts
Bosch GSR parts
Bosch PSB parts
Bosch GSR 18V parts
Bosch GSB 18V parts
Bosch drills can look very similar while using completely different internal components.
Once you've identified your model, use the appropriate exploded parts diagram to find the correct component and part number.
| Problem | Possible cause | Parts to check |
|---|---|---|
| Won't start | Battery, switch, brushes or motor | Battery, switch, brushes, motor |
| Keeps cutting out | Overheating, battery or electrical fault | Battery, switch, motor |
| Loss of power | Battery, brushes or armature | Battery, brushes, armature |
| Excessive sparking | Brushes or armature | Carbon brushes, armature |
| Grinding noise | Bearings or gears | Bearings, gears |
| Chuck not spinning | Gearbox or motor fault | Gears, gearbox, motor |
| Chuck slipping | Worn chuck | Chuck |
| Trigger not working | Switch/trigger fault | Switch, trigger |
| Overheating | Excessive load or mechanical fault | Bearings, motor |
| Torque not working | Clutch or gearbox problem | Clutch, gearbox |
These are possible causes rather than a definitive diagnosis. The exact fault will depend on the Bosch drill model and symptoms.
If your Bosch drill has been reliable and is otherwise in good condition, repairing it can be a sensible alternative to buying a replacement.
A drill that appears to be completely dead could have a relatively simple fault such as a worn switch, carbon brushes or damaged cable.
Even more substantial repairs can sometimes be completed by replacing individual components.
Before replacing the complete tool, check whether the faulty Bosch drill part is available and compare the cost of repair with buying another drill.
If your Bosch drill is not working, try these checks:
1. Check the battery or mains supply
Make sure the drill is receiving power.
2. Try another battery
If you have a cordless model, a known-good battery can quickly eliminate the battery as the cause.
3. Check the trigger
Make sure it feels normal and operates correctly.
4. Check the forward/reverse selector
Make sure it isn't sitting between positions.
5. Check the chuck
Look for damage, excessive movement or signs that it isn't gripping correctly.
6. Listen for unusual noises
Grinding or rattling could indicate gearbox or bearing problems.
7. Check for excessive sparking
Worn brushes or an armature fault may be responsible.
8. Allow the drill to cool
If it has overheated, give it time to cool before testing again.
9. Identify your exact model
You'll need this when looking for replacement Bosch parts.
10. Check the parts diagram
Use the correct diagram and part number before ordering.
Check the battery or power supply, trigger, forward/reverse switch and chuck first. If these are working correctly, the drill could have an electrical or mechanical fault.
Overloading, overheating, a weak battery, worn brushes, a faulty switch or another internal electrical problem can cause a Bosch drill to repeatedly cut out.
Some sparking can be normal in a brushed motor, but excessive sparking can indicate worn carbon brushes, a damaged armature or another motor problem.
Grinding noises can be caused by worn bearings, damaged gears or gearbox problems. Stop using the drill if the noise is severe or appeared suddenly.
If the motor isn't running, investigate the battery, switch, brushes and motor. If the motor runs but the chuck doesn't, there could be a problem with the gearbox or drive components.
Replacement chucks are available for some Bosch drill models. You must identify the exact model and spindle specification to make sure the replacement is compatible.
Some Bosch drills use replaceable carbon brushes. Always check the parts diagram for your exact model before ordering.
Identify the complete model number of your Bosch drill and use the corresponding parts diagram to find the correct replacement part number.
If your Bosch drill is not working, don't immediately assume that the complete tool needs replacing.
Start with the basics: check the battery or mains supply, trigger, forward/reverse switch and chuck. If the problem persists, components such as Bosch drill carbon brushes, switches, chucks, bearings, gears, armatures and motors may be available as individual replacement parts.
The most important thing when ordering Bosch drill parts is identifying your exact model. Bosch has produced a huge range of drills and combi drills, and similar-looking machines can use completely different components.
You can browse our full range of Bosch drill parts and spares or explore our Bosch spare parts to find parts for your specific machine.
Always remove the battery or disconnect the drill from the mains before inspecting or repairing it. If you're unsure about carrying out an electrical or internal repair, have the tool inspected by a suitably qualified professional.
