tlc is right Roger, After many heat cycles over the years the O-ring is likely brittle and cracked. Put a drain pan under the pump and remove the valve, You can likely match a O-ring up at your local hardware store, Otherwise a complete seal kit will be needed from Hydro-Gear......
Originally Posted by piston slapper
You never learn anything until you admit you don't know it all...
"Why go out preserved when you can go out beat up, worn out, sliding in sideways screaming, Holy Sh!t What A Ride" !!!