Yanmar 3ym20 raw water pulley.

[Tarn]

Hi The nut on my pump became loose, pump stopped working. I examined the pump and the pulley key slot had worn round and the pulley revolved on the keyed shaft.
The nyloc nut looks like the nylon was damaged.
The pump ran for minutes before stopping. I wonder was the pulley worn and after starting to rotate on the keyed shaft this caused the nut to become loose.
Or did the nut loosen and then the pulley wore round in under 5 minutes.
This pump has worked Ok for 5 years
Cheers Tarn

 

[VicS]

Nobody knows.

Make sure the shaft is not damaged before fitting a new pulley.

Also make sure the nut is correctly tightened , adding extra to the normal torque for the nut size to allow for the extra resistance of the Nylon insert