waterpump impeller threaded

[gezza]

Advice re threaded impeller needed
I have 2 x Yanmar SD40s. The port engine was having an overheating issue. I changed the impeller on the Johnson water pump. Having done that I decided to change the starboard one as well. Expecting the exact same experience, I was surprised to find that the impeller is threaded and therefore needs to be turned out rather than pulled out. I could not seem to get it to budge.
Does anybody have any advice - does it turn clockwise or anti-clockwise? is there a tool I need to use.
Any help appreciated

[Lepke]

You may have to pull the pump and then pull the shaft. Never seen one threaded, but use the same solution you use to clean marine growth in your heat exchanger. If it's a mix, make it much stronger. There's probably a similar buildup in the threads.
If it's a standard Johnson pump, you may want to buy a rebuild kit that includes a new keyed shaft.

[CarlF]

Not sure about your engine but my Yanmar has an impeller with a bit of thread that fits their special impeller puller tool (in picture). The thread doesn't extend onto the shaft.

The tool makes it a cinch to pull the impeller. If you don't have the tool, I think you can still pull it the regular way.

[HopCar]

I think Carlf has answered your question. I know some Sherwood impellers are threaded for a puller.
Sherwood 25105 Impeller Puller Tool

[gezza]

thank you guys. that makes a lot of sense - that its not threaded all the way - just to facilitate a puller. Smart idea
I'll see how I go, cheers