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How to Replace the Seal on My Troy-Bilt Horse Rototiller

By Ashley Hay ; Updated September 21, 2017

A Troy-Bilt Horse Garden Tiller is a gasoline-powered, walk-behind rear-tine rototiller that is powerful enough for heavy-duty work such as breaking new ground. Over time, the oil seals on the tine shaft of a rototiller are likely to crack from normal wear and tear. You will need to replace the oil seals so that the gears and bearings that turn the tines will continue to receive proper lubrication. Several steps are required to replace the oil seals, but the task does not require special skills or expertise.

Use a wrench to remove the five bolts and key securing the housing cover that protects the gear assembly on the rototiller's tine shaft. Depending on the age of your rototiller, disposable plastic washers may come off along with the bolts. Remove the plastic washers and discard them, as you will replace them with new ones. Once you have removed the bolts and key, the housing cover will be removable.

Slide the oil pan under the rototiller.

Sand the area where the key was located to remove any sharp edges.

Use a piece of tape to mark the left side of the tine shaft so that you know how to reassemble the parts, and then pull off the housing cover. You may need to use the soft mallet to gently tap the housing cover if it does not come off easily. Once it is loose, slide the housing cover off the shaft. Use care when sliding the assembly off the shaft to avoid damaging the bearing cup or any seals that do not require replacement.

Use a cloth to wipe off any dirt or other debris that may have accumulated on the tine shaft.

Slide the gear assembly off by pushing from the right side of the shaft. You may need to use the mallet to help remove the gear assembly. Take care not to damage the bronze gear, drive shaft or bearings.

Line the PVC pipe up to the oil seal, and tap it with a hammer until the seal cracks enough that you can pull it out.

Use sandpaper to clean up the shaft, then wipe it with a clean cloth. Build up of dirt and grease occurs over time, and you must remove it before you install the new seal.

Apply grease to both sides of the new seal, and then slide the new seal into place by sliding it onto the shaft.

Place the PVC pipe over the shaft and gently tap with the mallet to force the seal into place. The seal should be flush with the casing. A few gentle taps should do it.

Rub non-hardening gasket sealer around the outside edge of the seal.

Realign the shaft, if necessary, by placing it between two blocks of wood; tap on the shaft end to move it down until it will not move anymore. Flip the shaft over, and repeat for the other side.

Replace the gear assembly by sliding it back onto the shaft. Note the side that the tape is on, the left side, and replace it. Remove the tape.

Replace the bolts, and tighten them with the wrench. If disposable plastic washers were used, replace them with new ones before replacing the bolts.

Refill the oil in the transmission after the seals are installed.


Things You Will Need

  • Hex wrench or socket wrench, 3/8-inch
  • Oil drain pan
  • Sandpaper, 400-grit
  • Masking tape
  • Soft rubber mallet
  • Cloths
  • 1 Schedule 40 PVC pipe, 1 1/2 inch, 6 inches long
  • Hammer
  • Gasket sealant (non-hardening)
  • 2 Blocks of wood (optional)
  • Disposable plastic washers
  • Engine oil

About the Author


Based in Columbus, Ga., Ashley Hay has been covering animal health and wellness since 2004, and arts and entertainment since 2008. She holds a Bachelors of Arts in psychology from the University of Central Florida.