How to Replace a Log Splitter Flexible Pump Coupler



This DIY repair guide explains how to replace the flexible pump coupler on a log splitter. The flexible pump coupler connects the engine drive shaft to the hydraulic pump. The coupler is designed to break if the hydraulic pump seizes up, protecting the engine from damage. The pump coupler deteriorates over time, causing vibration and noise when the hydraulic pump is running. If the flexible pump coupler breaks or the coupler is worn, use the manufacturer-approved replacement part to install a new one.

Use these steps to replace the flexible pump coupler on Craftsman, MTD and Troybilt log splitters.

Repair difficulty:
Time required:

Less than 30 min.

Parts Required

  • Flexible pump coupler

For manuals, repair guides, and specific part recommendations, enter your model number.

Tools Required

  • Wrench set
  • Thin ½-in. wrench
  • Work gloves

Before you begin

Wear work gloves to protect your hands.


 Warning: Undertaking repairs to appliances can be hazardous. Use the proper tools and safety equipment noted in the guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs should only be performed by a qualified technician.

Step 1: Disconnect the spark plug wire

Disconnect the spark wire so there's no chance that the log splitter engine could accidentally start.

Step 2: Remove the hydraulic pump

Using the thin 1/2-inch wrench to keep the hex-head bolts from moving, remove the 3 flange lock nuts from the hex-head bolts that secure the pump to the flexible pump coupler shield.

Pull the pump off of the engine.

 Tip: The thin 1/2-inch wrench fits in the small between the heads of the hex-head bolts and the side of the engine.

Step 3: Remove the flexible pump coupler

Slide the coupling shield off of the hex-head bolts on the side of the engine.

Pull the flexible pump coupler out of the coupler halves.

Clean any residue from the broken flexible pump coupler out of the coupler halves.

Step 4: Install the new flexible pump coupler

Reinstall the coupling shield.

Position the new flexible pump coupler on the pump-side coupler half.

Slide yourself under the coupling shield so you can guide the coupler halves together.

Push the pump onto the hex-head bolts and guide the pump-side coupler half into the engine-side coupler half, rotating the pump-side coupler half to line up the coupler halves.

Reinstall the 3 flange lock nuts on the hex-head bolts to secure the pump on the engine. Tighten the 3 flange lock nuts securely.

 Tip: Use the thin 1/2-inch wrench to hold the hex-head bolts stationary as you reinstall and tighten the 3 flange lock nuts on the base of the hydraulic pump.

Step 5: Reconnect the spark plug wire

Attach the spark plug wire and make sure the log splitter engine works properly.

Step 6: Test the hydraulic pump operation

Start the log splitter and test the operation of the hydraulic pump and the flexible coupler.