Oil drips from the small gear case at the scooter's rear wheel, appears on the wheel or tyre, or turns up inside the belt case. The gear case holds only a small amount of oil, so even a slow leak can run it low and wear the gears. Leaks come from the drain or filler bolt, from overfilling (oil pushed out of the breather), from the seal where the axle comes out to the wheel, or from the seal on the belt side. Oil on the rear brake or tyre is a crash risk.
Is it safe to ride?
Ride with care only if the oil is not reaching the tyre or brake. If there is oil on the tyre, wheel rim or brake, do not ride until it is cleaned and the leak is fixed.
Quick checks first
- Wipe the gear case clean, ride a short way, and look where fresh oil appears.
- Look at the tyre sidewall and inside the wheel for oil.
- Check the drain and filler bolts are tight.
- Was the oil changed recently? It may have been overfilled.
Diagnose it step by step
1Is there oil on the tyre, rim or rear brake?
- Yes: stop riding. Clean the tyre and rim with detergent and water. Oil-soaked brake shoes or pads do not recover and must be replaced: Service a drum brake or Check brake pad wear. Then continue.
- No: go to step 2.
2Is oil coming from the drain bolt or filler bolt?
- Yes: fit new sealing washers and tighten to the manual's torque. Change scooter final drive oil if the level is in doubt.
- No: go to step 3.
3Was the case recently filled, and is oil coming from the breather?
- Yes: drain to the correct level using the measured amount in your manual.
- No: go to step 4.
4Is oil coming from around the axle on the wheel side?
- Yes: the output seal is leaking. This is a workshop job (wheel removal and seal replacement). Check the level and refill after the repair.
- No: go to step 5.
5Open the drive case (engine cold). Is there oil inside, on the clutch or belt?
- Yes: the seal on the belt side of the gear case, or the case gasket, is leaking. Workshop job. Oil on the belt and clutch makes them slip; the belt usually needs replacing: Inspect and replace the scooter drive belt.
- No: use Trace an oil leak; the oil may be coming from the engine above.
6After any repair, is the gear case filled to the correct level?
- Refill with the type and amount in your manual. If oil was lost for some time, check the drained oil for metal (Change scooter final drive oil).
Causes, most likely first
| Cause | How to confirm | Fix |
|---|---|---|
| Loose bolt or old washer | Oil at drain or filler bolt | Change scooter final drive oil |
| Overfilled | Oil at breather after a change | Drain to the correct level |
| Output seal (wheel side) | Oil around the axle, on the wheel | Workshop seal replacement |
| Belt-side seal or case gasket | Oil inside the drive case | Workshop; new belt |
| Engine leak running down | Oil above the gear case | Trace an oil leak |