Was having trouble keeping pilot lit on water heater. It would light just not stay lit. I went and bought a thermacouple & put on. Lit easier but went out. I tried to relight it and I can't even hear the gas coming through for pilot? Just wandering where to go next. After I changed the thermacouple it seemed to take 3 or 4 pushes of pilot button before gas was coming through. Any info. Would be great. Thanks, Robert

Does your water heater have a standing pilot light or does it have a igniter? Have you read directions on water heater about lighting pilot light?

Water heaters have change so much in the last few years its hard to give instructions with out more information

Chances of gas valve being defective are remote.

Does this water heater gas line have a dirt leg on it? It is possible that the gas line has accumulated pollutants in it and caused the pilot tubing and orifice to become clogged. You could remove the gas line from the valve to the burner and clean out the dirt leg and perhaps try to clean out the burner tube by blowing air from a compressor, on a low setting, back through the line from the pilot orifice and tube to remove any build up in the burner. Most commonly these situations occur in gas lines with no dirt leg installed. I had a furnace with a similar problem and cleaning the pilot tube and orifice solved the problem. I also added a dirt leg to the configuration and removed the copper pipe that had been imporperly used when the furnace was put in before I bought the property and replaced it with black pipe. Hope your situation is as easily remedied.

Yes I have. It says to turn control valve to pilot position press, light, once lit hold 60 seconds and depress, turn to on. So here is what I have been doing. It has been lighting great, not like before thermocouple was replaced, but going out at somepoint in the night when not used for awhile. However, the amount of time has been less and less. Like i.e. hours to minutes. And now it will not even stay lit after I let off pilot button. The thermo is glowing red so I know its hot enough to tell the valve to send gas but, no button = no gas = no light and now (as of tonight) I really have no hot water. Everything I've read says if it doesn't stay lit it's the thermocouple so I spent 8 more bucks on a good back up and notta? Calling to price valve/stat tomorrow. I removed burner/pilot assembly cleaned. Nothing but cold water. Thanks, I would says its probably 8-12 yr old reliance 501. Thanks for your help, robert

Suggest that you make sure of the connection of the thermocouple to the gas valve. Remember it is a low (very low) voltage electrical connection. Might try to blow out internal threads of connection to gas valve.
It may be the gas valve but gas valves are very reliable. Don't think I have ever had to replace but one.