I had a weird rumble and some dribbles out the weep hole of my water pump on my Ferrari 360 so while I was in there for a belt change, I decided to do the water pump rebuild.
The water pump on a Ferrari 360 is unusual in that to repair it, the bearings and seal are replaced instead of just replacing the entire unit. Rebuilding the water pump isn't trivial. It requires some specific tools, like a press (2 ton minimum) and suitable dies (30mm socket worked for me) to press out the existing bearing and seal and install the new ones, and a Ferrari specific tool (PST-01) to install the seal.
The special tool is required because the seal (G in the diagram) has to be pressed into place on two surfaces. The body of the water pump and the impeller shaft. In between is a fragile seal made from ceramic and plastic that is easily deformed, crushed, broken, or shattered. The special tool keeps the stress off the seal and on the metal surfaces of the seal so that both are pressed down to the right depth at the same moment.
The tool is rather simple but requires a tight tolerance. Since those tolerances, and the PST-01 tool are unavailable, it has to be designed and built before the seal can be installed.
From what I can figure, it looks like the shaft seal has to end up being on the same plane as the back of the impeller. The body seal has a stop built into the body where it ends up. The difference between those two heights is also the distance between the shaft seal pressing surface and the pressing surface of the body seal. By measuring the above diagram, it looks like about half an inch. A good starting point.
To make the tool, I'd like to just 3D print it. That's my favorite way to make things. If plastic isn't strong enough, I can make one out of aluminum either with my CNC or metal lathe. The simple way is to just print it.
The question with plastic is always "Is it strong enough?" A lot of force is needed to press the seal into place. How much can a plastic tool stand before deforming? How much force can the seal stand before deforming? If the plastic tool can handle more than the seal, then it should be fine.
To find out, I made a test article with similar dimensions and ran up the pressure on the press until it failed. The seal started to deform at 1250 lbs., and the plastic didn't deform until 2500 lbs. The plastic passed.
Here's the test article in the press.