My 1991 mazda 929s is running hot and water is coming out from behind the crankshaft...any ideas. We have put a new water pump on and the water is not coming from there.

Sounds like the pullys are not lined up or one has a defect

First put something like paper down under the area of the leak. You will also need to see what type of oil it is.....black-oil; red-transmission fluid or power steering fluid; clear-power steering fluid; green/yellow-cooling fluid.....etc.

new water pump required,its driven by the timing belt

What motor....L 4-218cc 2.2L 2200 2-bbl
L4-218cc 2.2L 2200 MFI or L4-2606cc 2.6L SOHC ?????

What I would do is think about a blocked radiator. Pull off the top and bottom hoses from the engine, leaving them connected to the radiator. Then dump a bunch of water into the top and check the flow out the bottom. if it comes out way slower than you are putting it in, you need a new radiator. Car that old you do not know what all has been dumped into the radiator over the years, or how much **** has just built up in it.

water pump

Have no idea, but it's not hard to trace the hoses... they basically consist of an out from the water pump, and into the radiator, the out from the radiator and into the thermostat water jacket... then there will be 2 heater core hoses, in and out, which will be located on the firewall to the rare of the engine compartment. But if it's overheating the likely cause wouldn't be clogged hoses, unless of course you are leaking coolant which I'm sure you'd have noticed already. While the car is running and warm feel the coolant hoses, if they feel pressurized and hot then your water pump is likely good, and the likely cause would probably be the thermostat. Easy fix and cheap, too...

The O-ring should fit into a groove on the back of the water pump or it's mating surface.

If you didnt have the crank ground or the rods resized and over sized bearings instaled then the issue with your engine is beyond advice other than remove engine and rebuild correctly as there is too much clearance and the oil cannot build enough pressure especialy when hot as it thins out and becomes harder to maintain pressure.Your problem is crankshaft bearings have excessive clearances or oil pumps pressure relief valve is jammed/jamming.good luck and hope its just the pump.

you could also have a cracked or pitted head letting water into your cylinders .check to see if you are blowing water out of your exhaust if you rev slighty.this happenes if you do not use coolrant .straight water is not a good idea with aluminium heads,can cause corrosion