DK,
YES, IT IS CRITICAL TO REMOVE THE BROKEN PIECE OF BOLT BEFORE PUTTING THE PUMP BACK ON THE MOTOR.
I think you found the source of your leak. That broken piece of bolt has to come out of there. The problem is that the pump part is aluminum, i.e. soft metal. The bolt is "HARD" metal.
I think you can safely leave the "crossover" tub and its "O" ring in the thermostat housing. A pressure test can be done before you put the intake back on. If it does not leak you will not have to disturb it.
Now for the broken bolt. The goal is going to be to carefully drill into the center of the broken piece of bolt, and extract it. If the pump is not that old the two different metals should not be fused together.
Sears sells a broken bolt extractor set. There are three or four different sizes of drill bits and an extractor attached to each drill bit.
When the hole is deep enough into the bolt it grabs onto the piece and screws it out. The drill bits are made to run in reverse, that is counter clockwise, so when the extractor grabs the piece it is backed out. These work realy well.
You must be realy careful to drill in the middle of the broken bolt. Lubricate the drill bit with some PB Blaster. If there is any part of the piece of bolt sticking out of the front side, you could grab it with a vice grip and turn it out.
If this is not possible, then center punch it and drill into it, and use an extractor, such as the Sears, or an easy out. If you think you might mess it up, you could take it to a machine shop, or a good auto shop, and have them remove it.
I'm glad you got the crank sprocket off OK. Clean any and all corrosion off of the crank, woodruff keys, and the inside of the sprocket and pulley. Apply a thin coat of grease to the inside of the sprocket and pulley, and to the crank and woodruff key. This will keep them from corroding.
Do a search for SDPATT's explanation of how to properly install the front crank seal, and the CPS if applicable. Be very careful not to bend, distort, or otherwise damage the piece that rotates through the CPS.
Once the piece of bolt is removed from the pump body, repair any damaged threads. Hopefully this will not be necessary. When you assemble the pump use anti-sieze compound on the bolt threads, AND use a torque wrench.
The torque on the small bolts, like the one that is broken, is very light. Seven foot pounds comes to mind, but I do not remember for sure, so look it up. In fact I think I remember it being something like 80 inch pounds.
The larger bolts were something like 15 foot pounds. Again, look it up, as it is very easy to strip aluminum threads, and break small diameter bolts!
The most common causes of water pump failure are the seal and the bearing. The impeller can become encrusted with mineral deposits, like calcium, lime, etc., and fail to effectively move (pump) the coolant.
Mixing you anti-freeze with deionized, PH neutral water will eliminate, or at least minimize, this problem. It will also minimize the mineral build up in the rest of the system.
Thank you SHOZ123 for the PH neutral part of that. In fact it was SHOZ123 that pointed out the benefits of using a reverse drill bit for extracting broken bolts. thumbs_u
As an aside, the bits and pieces of expertise, knowledge, and experiences we share make us all better at working on these and any other cars.
DK, I am working out of town, and am without benefit of my references, or my personal e-mail. I will check the forum several times during the day for any questions you have.
Hang in there buddy, there are only one or two small obstacles left to overcome. Then we can break out the bottle of Tennessee mineral water (Old No. 7 in the black label).
rangerj
