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.
Disconnect the spark plug wire
Disconnect the spark wire so there's no chance that the log splitter engine could accidentally start.
Disconnect the spark plug wire.
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 space between the heads of the hex-head bolts and the side of the engine.
Remove the flange lock nuts.
Remove the pump from the engine.
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.
Remove the coupling shield.
Remove the flexible coupler.
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.
Reinstall the coupling shield.
Reinstall the flexible coupler.
Reinstall the hydraulic pump.
Reinstall the flange lock nuts.
Reconnect the spark plug wire
Attach the spark plug wire and make sure the log splitter engine works properly.
Reconnect the spark plug.
Test the hydraulic pump operation
Start the log splitter and test the operation of the hydraulic pump and the flexible coupler.
The flexible nylon pump coupler deteriorates over time. Replace the flexible pump coupler if it begins to vibrate or rattles, which are early indications that it’s failing.
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