Somebody may have come up with this already, but it's new to me. The idea is pretty simple:
Make pumps overheat if they are pumping lava. Require water cooling.
Now that last part is the tricky part, since people are clever. Obviously cans won't work, since that's just another ender chest waiting to happen. And you can't require the water to be pumped in (all you'd need is a liquid transposer). So I'd suggest that, if pumping lava, the pump must be adjacent to at least one water source block.
Done! Right? What did I miss?
Make pumps overheat if they are pumping lava. Require water cooling.
Now that last part is the tricky part, since people are clever. Obviously cans won't work, since that's just another ender chest waiting to happen. And you can't require the water to be pumped in (all you'd need is a liquid transposer). So I'd suggest that, if pumping lava, the pump must be adjacent to at least one water source block.
Done! Right? What did I miss?