Is my water pump failing?

Ok I’m stumped. How do I get the main gear off the shaft so I can disassemble the old pump? I got the front nut off with an impact wrench while gripping the shaft with pliers. But I can’t get the gear off. I thought it would just slide off with the nut gone. I’ve tried prying it off with pressure on both sides, gripping it with a rag to twist it, etc. it won’t budge.

ok this makes sense. I tried prying between the pump housing and gear with two wrenches but I was afraid to get too…violent with it. There is a key way though in the gear disc. Just like an impeller would have. Does that change anything?

I ordered a gear puller set - wasn’t too expensive. Will report back hopefully when I have it apart.

Separately, on the matter of the gears, with access covers off I was able to inspect most of the gears, including rotating them, and not seeing any other signs of wear or damage. Seems the water pump gear was the only damaged one. Not sure how to explain that, but a good sign nonetheless. Still plan to pull a sample once I can run it again and get things stirred up.

The plot thickens. I just removed the raw water pump from the other engine, and it has the exact same damage. One chipped tooth, and a wear pattern on about 1/4 of the blades.

What would cause this? I’ve inspected the main gear and there doesn’t seem to be any corresponding damage to it.

On the road now but will check on both these questions. It seems if there was an interfering bolt more teeth would be broken. In any case, i think it would have to be from the pump mounting side, not the cover side, since the damage is on the pump side of the teeth.

The pump gear metal is definitely different than the metal on the main gear that drives all of the accessories. The pump gear is grey whereas the main gear has more of a gold color.

Searching a bit more online I found a thread from 12 years ago where someone had the exact same problem- even saw deterioration on a new pump installed after only 3 years. This was for a TAMD63P - similar but not the same engine. Water pump is a different part number but looks superficially similar. There was no resolution, only speculation that there may have been 2 generations of pumps, an earlier 2 bearing pump and a revised 1 bearing version where the shaft was better supported.

The pump for the 74p has a shaft supported by 2 bearings. There are two different pumps for different 74p sub-models but they are both 2 bearing designs.

It seems like if this were a common enough problem to happen for both of my engines there would be more on the internet about it? These engines were pretty ubiquitous and lots of people still running them.