Symptoms
- Dark grease or oil residue around the chuck or gearbox housing
- Greasy film on hands or bits after use
- Drops or smears left on the work surface or storage case
- Grease visible seeping from housing seams
Likely causes
- CommonNormal minor grease migration from internal lubricationGearboxes are packed with grease at the factory, and a small amount can work its way out over years of use, which is usually harmless.
- PossibleWorn seal around the spindle or gearboxA degraded seal lets more grease escape than normal, especially with heavy use or age.
- PossibleTool was serviced or opened previously and overfilled with greaseExcess grease added during a repair can seep out until it reaches a normal level.
- Less commonHousing crack from a drop, allowing grease to escapePhysical damage can open a new path for lubricant to leak.
What to do
- Wipe away visible grease and monitor over the next several uses to see if it's a one-time residue or an ongoing leak.
- Check the housing for cracks or damage, especially if the tool has been dropped recently.
- Keep the chuck and bit area wiped clean so grease doesn't transfer to your work or hands.
- Avoid running the tool at high loads for extended periods if leaking increases, since low lubrication can accelerate gear wear.
- If leaking is minor and doesn't increase, it's often not worth opening the tool, since air rushing to reseal can void a warranty.
- If leaking is heavy, ongoing, or gears feel gritty afterward, have a repair shop inspect and reseal the gearbox.
Tools and parts
- Cloth for cleanup
When to call a pro
Persistent or heavy grease leaks should be checked by a repair shop, since running a gearbox low on lubricant can cause premature gear wear.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.