What year was this rheem water heater model 81x-66d made

SOURCE: dripping from drain spout

If you are refering to the "Dripping coming from the preasure tempature valve,Then just turn off the valve where the water goes into the heater and open the P/T valve with a bucket below it draining only emought water to get below the level where it reaches.     Normally the drain valves are plastic with a Male hosebib attached.  Attach a  garden hose to the rain and run it out to a point lower that the vaslve in order for gravity to drain the tank.The valve opens counter clock wise. If the valve is stuck or does not drain,and you have a foor drain handy,remove the whole valve and replace it with a boiler drain valve.  If The tank is located below the drain level then you will have to either pump or carry the drain water to the higher level.     Replace the P/T valve  and reinstall the associated associated piping. I would use tefelon tape on the P/T pipe theads.    You may have to open a hot water faucet in order for the air to replace the water in the tank ,in order to drain. 

SOURCE: the water heater will cycle 5-6-7 times with no

there is a screen around the bottom of the unit? if so take it off and clean it,, does this unit have a self ignitor, or is it piliot? make sure your flue is clear so the unit is not over heating,, make sure on the power vent that the filter is clear also,, does the fan come on before the gas ignites, if not the circuit board is going bad the fan should start first to omit the gas fumes

SOURCE: I have a Rheem glas fury model 22-40 gas water - leaking

once they leak it's time for a new water heater. ther is no way to repair a tank leak

SOURCE: Rheem water heater turns off by its self

Flashing code 76 is lost communication between the remote and the burner control assembly CCA (circuit card assembly). The CCA is still under warranty if purchased within the last 3 yrs. Contact Rheem customer service and have your Mod. and S/N available....explain to the agent you are recieving - flashing code 76...they'll walk you through the process.

SOURCE: rheem gas tankless water heater with error code c4 13

problem is inside burner compartment o2 sensor dirty or block..need to have a qualify technician clean it.