How to Change a Lawnmower Oil Seal

Written by mark o'brien
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How to Change a Lawnmower Oil Seal
Change the oil seal in your lawnmower to protect the engine. (Jupiterimages/ Images)

If you notice your lawnmower's oil level is lower every time you check it before use, then there is a good chance that the oil seal has deteriorated in a spot and is leaking. The oil seal is located between the engine block and the oil pan on the base of your lawnmower engine. You can order a new oil seal at any lawnmower sales store.

Skill level:
Moderately Easy

Things you need

  • Socket wrench
  • Socket set
  • Wrench set
  • Oil drain pan
  • Wood block
  • Rag
  • Oil seal gasket
  • Ft-lb torque wrench
  • 5W-30 oil

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  1. 1

    Tip the lawnmower on its side. Remove the oil drain plug from the base of the oil pan under the engine with the proper sized socket. Set the mower down flat over an oil drain pan to catch all the oil.

  2. 2

    Tip the mower back on its side and replace the oil drain plug and tighten.

  3. 3

    Wedge the block of wood between the blade and the side of the mower deck to prevent the blade from spinning. Unscrew the bolt holding the blade to the crankshaft with the proper sized socket. Remove the blade.

  4. 4

    Lay the mower down flat. Remove all the bolts holding the base of the engine to the lawnmower frame with the proper sized sockets.

  5. 5

    Pull the engine off the lawnmower frame and set it upside down so the crankshaft is pointing into the air.

  6. 6

    Unscrew all the bolts on the base of the oil pan with the proper sized sockets. Slide the oil pan off the crankshaft.

  7. 7

    Peel the remaining old oil seal gasket off the area between the engine block and oil pan. Wipe the area clean with a rag. Lay the new oil seal gasket in place. Slide the oil pan back down on the crankshaft.

  8. 8

    Finger tighten all the bolts into the oil pan. Fit the proper socket for the bolts on the foot-pound torque wrench. Tighten a bolt down with the torque wrench until the meter on the wrench reads 15ft-lbs. Tighten down the bolt on the opposite side of the one you just tightened. Continue this around the oil pan until they are all tight. Tightening opposite sides of the oil pan will properly seal the oil pan gasket.

  9. 9

    Place the engine back on the frame. Tighten the bolts through the engine block base into the mower frame with a standard socket wrench.

  10. 10

    Tip the mower on its side. Tighten the bolt that holds the blade back onto the crankshaft with the proper sized wrench. Use the block of wood as a wedge to tighten the blade.

  11. 11

    Lay the mower back down flat. Unscrew the oil dipstick and add oil to the engine until it is to the full line on the oil dipstick.

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