If you have a leak spraying out of the seal between the pool pump housing and the motor assembly, you probably need to replace the housing gasket between the two units. We recommend that when you pull the pool pump motor assembly to replace this gasket, you also replace the diffuser gasket within the motor assembly.
Assuming that you could not fix your leak by tighening the bolt, your first step is to order gaskets for the pool pump. You should have these on hand before starting your pump repair. You can order the pool pump gaskets separately or order a gasket package, GO-KITS, that includes the four gaskets and seals required for a general pump repair. This How To Page addresses replacement of the housing and diffuser gaskets. Replacement of the strainer gasket and shaft seal are covered in other How To Pages. Note: These gaskets are generally unique to the make and model of the pump, e.g. this set will only fit the Hayward Super II Pump. Order the set of gaskets specified for your pump's make and model.
Next you will have to relieve the pressure that has built up in the pool pump and water line. Note the pressure on the pressure gauge. It will typically read between 15 - 20 psi. Note this value for future reference when you restart the pump. To relieve pressure turn the air relief valve on top of the pool filter counter clockwise. Water will spray out initially as you see the pressure on the pressure gauge go to 0 psi.
Clean out the groove in the pool pump housing assembly. A small screwdriver covered with a layer of cloth works effectively.
Insert the new housing gasket in its groove. These new gaskets are tight. You may have to have someone hold half of the gasket in the groove while you are inserting the other half. Put a thin coat of lubrication on the gasket. Use a good pool parts lubrication. Some common lubricators, like Vaseline, will deteriorate gaskets.
Replace the motor assembly back into the pump housing. Insert and tighten the 6 bolt that bind the motor assembly to the pump housing. To ensure that the motor assembly seats properly inside the housing, loosely tighten bolts in alternating sequence - 1,3,5,2,4,6, then go back and tighten them down again in this sequence. This is important for proper operation of the pool pump. Hand tighten firmly.
Since the water drained out of the pool pump when you opened it up, you will have to prime the pool pump before turning it on. Open up the strainer and fill the strainer pot with water. Clean any debris out of the strainer basket while it's open. Close strainer lid securely.