Fire brick repair

[Maple Dan]

I have an arch made from an oil tank. This has worked great for the last several years. Today I notice 3 fire brick had come loose and fallen in. Is there a way to repair it if I let cool over night and then fire up or will it cure to fast. To much sap to leave for a few days. I am concerned if I leave it untill the end of the season I may burn through the tank. It is the top at the door end so really should be a cooler area if there is such a thing. Thanks for the help.

[Ghs57]

I just replaced a few missing bricks in my arch. I used premixed refractory cement and stuck them back in. Follow the directions. It may need some time to cure before firing. Put a small heater or incandescent light in there to keep it warm. Small first fire for an hour or it may bubble up. Good to go after that.

[maple flats]

If you decide to hold off, that will be ok most likely too. Back when I was a teenager, my dad had converted a cow barn into a work/repair shop. In there he made a heater by taking a whole oil tank, cut a big door in one end and made a hole for a stack on the top at the other end. He then hooked it to a chimney and burned pallets for heat. They burn real hot. That heater had no brick in it, just a grate and a large fresh air inlet under the grate. He burned it real hot to heat the shop so he could repair his construction equipment. That heater was used like that for 15-20 years, and when we took it out a few years after selling the machinery and retiring, the heater was still solid.
While it will lose heat where the brick is missing, I'd likely wait for warm weather. Then re-brick it properly. The only exception might be if the steel has major pitting in that area.