How to: Re-thread Your Sump Plug

Whether you’ve done it yourself or the previous owner has, a cross-threaded sump plug can be really annoying during an oil change. You think you’re done and then you come back to the garage to find a patch of oil beneath your bike.

How does it happen? It’s either by over-tightening the bolt, causing it to turn in the same spot and shred the existing bolt, or when the bolt is not aligned quite properly before tightening, effectively cutting across the threads.

The result is the same – the bolt won’t tighten fully, or it tightens to a point and then loosens again. This results in an oil leak, which can be dangerous when you’re riding and costly in constant oil loss.

Luckily, the fix is fairly simple.

Tools:

  • Thread repair kit, like this. Make sure the sizing is 1mm bigger than your current bolt size. Check eBay and Amazon for different sizes.
  • Adjustable spanner
  • Torque wrench and appropriate socket

Steps:

  1. Unscrew the existing sump plug bolt (counter-clockwise).
  2. Line up the thread tap, perpendicular to the hole.
  3. Turn the thread tap clockwise, pushing up gently as you do. Do this with your fingers first, to maintain alignment. Be patient and wait for it to ‘catch’ the metal. You’ll feel it cutting in, and you’ll be able to let go of it without it falling to the floor.
  4. Continue turning the tap with the spanner, turning it back once for every two turns.
  5. Repeat until you’ve cut deep enough to screw the new bolt all the way in. Keep checking to ensure you maintain alignment.
  6. Unscrew the thread tap all the way.
  7. Screw the new bolt and washer into the sump and finger tighten (clockwise).
  8. Tighten gradually to the required torque with the torque wrench.

Job done!

You should now have a seal and no oil leaks. No need to replace the sump and pay for costly fixes. All done for under £15.