My eXmark Metro Crankshaft Is Vibrating

Crankshaft

• Bent crankshafts aren’t common, but they can happen if a blade strikes a boulder while the engine is on high. Don’t try to straighten the crankshaft; it’s not safe. Bent crankshafts need to be replaced. Running your lawn mower with a bent crankshaft will damage other parts of your lawn mower, including the main bearings and connecting rod. Crankshaft repairs are expensive unless you have access to used parts and can do the work yourself. In some cases, it might cost less to buy a new lawn mower.

Blades

• A lose blade mounting bolt or blade pulley can also cause excessive vibration in your mower. Check the mounting bolt and pulley and tighten them, if necessary. Vibrations can also occur if the blade spindle is bent. According to the manufacturer, this is not a problem you can deal with yourself; you will need to contact an authorized service dealer. Bent or unbalanced cutting blades can also cause vibration. Check for a bent blade by picking a reference point on one side of the blade and measuring the height of the blade tip at that spot. Rotate the blade 180 degrees and measure the height of the opposite blade tip. If the difference is more than one-eighth of an inch, either the blade is bent or the crankshaft is bent. If it’s a blade, you will need to install new ones.

Engine

• Abnormal vibrations can also be caused by loose mounting bolts on the engine, or a loose engine or idler pulley. Inspect the mounting bolts and pulleys and tighten them, if necessary. If your problem is a damaged engine pulley, you will need to contact an authorized service dealer.

Belt

• Another reason your lawn mower might vibrate excessively is if you have a damaged drive belt. If this is the case, you’ll need to install a new one. The tension on the new belt should be checked after the first hour of operation and again within the next 23 hours. If necessary, adjust the tension by loosening the 5/16-inch whiz lock nut on the turnbuckle and rotating the turnbuckle toward the rear of the mower to tighten the tension, or toward the front of the mower to loosen it. A secondary drive belt, found only on 48-inch models, should also be checked.