6LPA-STP Impeller replacement

Has anyone changed the impeller on their Main ship 30' Pilot, 315hp Yanmar? Do I need any factory tools, puller? I can't really see it too well from top of the motor or from inside the cabin looking through the access hatch? I have the service manual breakdown of the parts and a paragraph on the replacement. Seems pretty straight forward? Maybe I need a mirror? Any constructive comments would be great.

I bought a puller for my little Yanmar 4jh engine, and I'm glad I did. It's so hard to get to the impeller, without the puller it would have been way harder.

My impeller had threads on it and the puller screwed onto those threads. Looked like this:



Maybe your impeller is similar?

We pull the pumps and change impellers on the bench and re-install.

I had a Pilot with the smaller engine. I know probably no comparison. BUT, I have seen many boats, including my Mainship, where it is MUCH easier to take the whole pump off to change the impeller. The 4LHA was pretty much impossible to change without doing it that way. So weigh the possibilities of doing that.

Thanks Gentleman. Since the 30' pilot engine room is not conducive to larger folks, anyone over 90 pounds. I will try and pull the entire pump. I will locate the additional o-ring on the pump-motor side before removing. Thanks again.

For anyone replacing or rebuilding your 315HP Yanmar raw water pump.

I had to remove the top stud in order for the pump gear to clear the housing. The back of the pump hits the forward engine mount. I twisted and giggled but could not clear the end of the stud. I sent Johnson Pump and email and they sent me the attachment, which is the cut sheet for the pump. The Johnson # is 10-24493-01 If you rebuild the major kit from Depco is 119773-42500. This answered a lot of questions on how to rebuild the pump. I took it apart last night and the impeller was over due, missing a couple veins. I'm still not to sure how they come up with the placement of the bearing on the shaft? There is not lip or seat that the bearings press up against. I guess you just measure the bearing distance from the end of the shaft? I understand you do not press the bearings across the shaft where the seals sit.
Hopefully it all works once I reassemble the pump tonight?
Jeff.