The John Deere LT166 features a 16-horsepower, V-twin engine, twin-touch pedal, hydrostatic drive and a 48-inch mower deck. The mower deck is run by a single belt that wraps around the pulleys on the mower deck, and then up to the pulley on the crankshaft. After hours of operation, the belt starts to wear down and cracks. When this happens the blades will start to slip, causing a poor quality of cut. Replacing the mower deck belt takes roughly 40 minutes.
Park the lawnmower on a hard, level surface and set the parking brake. Turn the key in the ignition to the off position.
Pull the mower engagement PTO level located on the right side of the dash all the way back. Raise the mower all the way up by pulling back on the mower lift level on the left fender deck, until it locks into place.
Turn the cutting height knob below the operator seat to a 1-inch setting. Place wooden blocks under each side of the mower deck; make sure the blocks are not under the gauge wheels. Push the mower lift lever all the way forward until it locks into position.
Slide the mower belt off the front pulley located under the engine. Remove the spring locking pin and washer from the tension rod on top of the mower deck, on the right side; pull down on the tension rod to release. Disconnect the mower deck rear pins, right rear side, in front of the back tire and slide out the pin. Repeat this step for the left-side pin.
Remove the spring locking pin and drilled rod in the front bracket directly below the muffler. Push the mower deck slightly forward and slide the draft arm assembly out of the hole in the front bracket. Unhook the draft rod from the front of the mower deck and remove. Pull the mower deck lift lever all the way back and remove the wooden blocks from under the mower deck. Slide the mower from under the tractor from the right side. Install the new mower deck by following the routing diagram in the Resources section below. Reinstall the mower deck by following the instructions in reverse.