Keeping pulley separated from pump on raw water pump

[OfficeMonkey]

I replaced the pump on my raw water pump -- it was a JABSCO 2620 and had been unmaintained for entirely too long. I replaced it with an identical model to be sure mounting would work. I tried to replace the pulley itself, even buying the identical Chicago Die Cast 400A pulley. The pulley arrived WITHOUT the cutout for the key on the end of the Jabsco shaft, so I went back and reused the old pulley. I ran her seemingly without trouble for about 20 hours over the last two weeks. I checked several times over the first few hours, and didn't notice anything wrong.

Today I took a look for a different problem, and was horrified to discover bronze shavings all over the engine compartment. Apparently the pulley had slipped down further on the shaft and scraped along the outer edge of the pump. Currently, the pulley is not even remotely in contact with the pump, so the pulley is definitely sliding along the shaft while it spins.

It's not directly an Atomic 4 question, but I'm hoping someone has some suggestion on how I might keep the pulley in a fixed position along the pump shaft. Help?

[Al Schober]

A set screw is pretty standard for that application. I would have expected the old pulley to have been drilled for a set screw, but not necessarily the new one.
If the hole for the set screw is close to the pulley, you may need a longer tap drill and tap. We used to use pulley taps pretty frequently, not necessarily for pulleys. They should be available through a supply house or McMaster Carr.

[OfficeMonkey]

Five minutes of feverish reading later: I have a set screw!

It's doing a good job of keeping the pulley spinning with the shaft, but it's not locked to anything to keep it sliding up and down the shaft.

Should I create a "dent" (the old one had almost melted the key and the shaft together)? Just tighten the set screw more?

[Al Schober]

The pulley and shaft should have a key to keep them rotating together. The setscrew should just serve to keep the pulley from moving axially on the shaft. And yes, putting a divot in the shaft for the set screw is recommended. Such a divot is really needed in your propulsion shaft where there are axial loads, but not really needed for a water pump. I the pulley on the pump aligned with the pulley driving it?

[OfficeMonkey]

I've tightened the set screw, but I'm not convinced that it's enough. I'm testing the engine this weekend, so I'll mark the location of the pulley before and check if again afterwards. If it slides at all, I'll go with a divot.

My engine is mounted at a reasonable angle (of course), and it's possible I made the belt too tight. I'm not sure why it's sliding -- but it definitely is!