Riding Mower and Tractor: Mower deck vibrates

If the mower vibrates when you engage the cutting blades, there might be a problem with the blade drive system. Deck vibration can be caused by an unbalanced blade, worn pulley or mandrel, bad blade belt or debris caught inside a pulley. Loose nuts or bolts on the pulleys, mandrels or blades can also cause vibration. Remove the mower deck and re-tighten all fasteners. Check for wear on pulleys, mandrels and blades. Replace any worn or damaged components.

These repairs may help solve your Riding Mower and Tractor problem:

Replace the riding mower mandrel assembly

Mandrel assembly

The mandrel assembly attaches to the deck and spins the blade to cut grass. A blade won’t move if the mandrel locks up. A damaged mandrel causes mower deck vibration and uneven cutting. Examine the mandrels regularly and replace any damaged mandrels.

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

Replace a riding mower blade

Mower blade

A bent mower blade won’t cut grass evenly and may cause mower deck vibration. Dull blades leave ragged edges on cut grass. Inspect mower blades regularly and replace a riding mower blade if it’s damaged, bent or dull.

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

Replace the riding mower blade belt

Blade belt

The blade belt spins the blades to cut the grass. A worn or broken drive belt won’t spin the cutting blades so your mower won’t cut the grass. A worn blade belt can also cause mower deck vibration or uneven cuts. Examine the blade belt regularly and replace it if it’s worn or broken.

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

Replace the riding mower deck idler pulley

Deck idler pulley

The deck idler pulley tightens the blade belt against the blade pulleys to spin the blades when you shift the blade engagement lever to engage the blades. You might need to replace the riding mower deck idler pulley if the blades don’t spin. A worn idler pulley can also cause uneven cuts and mower deck vibration, so check the idler pulley if you notice these symptoms. Replace the deck idler pulley if it’s worn or broken.

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