Inspect Engine Belts


Why Engine Belts Are Important

Engine belts transfer rotational power from the crankshaft to the pulleys (sheaves) that drive the engine coolant circulating pump, one or more alternators and often the raw water pump. If the belt on the circulating pump fails, the engine cannot be operated. (If the raw water pump belt fails it may still be possible to rig up a gravity-fed raw water supply).

Inspect engine belt from Marine Diesel Basics

How to Keep Engine Belts Running  

Correct tension and near perfect alignment of the pulleys (sheaves) are the two essentials for long belt life. Poor alignment and/or tension can destroy a belt within a few hours.

V-belts transfer their energy to the side walls of a pulley and should not touch the bottom of a pulley's V. Replace the belt if it "bottoms out".

Be sure to match the correct-sized belt to the pulley - there are many similar, but slightly different, designs to choose from. "Close enough" will quickly fail.

Poor pulley alignment – belt wears and fails

Too little tension – belt slips, equipment (such as alternator or pump) fails to operate properly. Belt "squeal" is often a tell-tale sign of a loose belt, though, more rarely, it can also be caused by a belt running around a seized pulley.

Too much tension (overtight) – strains bearings, likely leading to premature failure of the bearing and pulley.

Belt dust – evidence that alignment or tension need adjusting.

Time taken to get both alignment and tension "perfect" will be rewarded with much longer service life and trouble-free running. 

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