Well the thing is, I was working in the area, so there's no way the water source wasn't loaded, in fact I was closer to the water source then the engine until I went to the house to sleep. Lay in in... BOOOOM
If it's not a chunkloading issue, then it's because you built it wrong... there's some behavior of waterproof pipes that hardly anyone pays attention to, even when they should be intimiately familiar with it from using Redpower tubes. I am talking about backflow.
When liquid traveling along a waterproof pipe hits a dead end, it doesn't stay there. It reverses direction and flows back. Why is this a problem? Because each individual pipe section can have only so much liquid flowing through it at any one time. When you are relying on water flowing from A to B, but half the pipe's capacity is taken up by water backflowing from B to A, then B is only getting half as much water as you think it does. Only when the pipe is completely full, meaning no air left anywhere along its length, then the liquid stops sloshing back and forth and stabilizes. When you then start drawing water, it will flow forward in just the required speed and never cause backflow. Also, if the pipe is empty and any arriving water finds a machine to flow into, then it won't backflow either (even if the machine consumes water much slower than it arrives).
How does backflow happen?
- A machine that consumed water before from a pipe that was not 100% full suddenly stops consuming water (a carpenter running out of materials, a combustion engine switched off by a lever).
- No destination exists for the water to go to (during construction, before you add machines that consume water).
- A T-junction exists in the system. This is a big no-no in critical cooling lines because as soon as the side arm experiences backflow, it will always, always choke the pump down to a fraction of its output even as the main arm continues to draw water, starving it. All cooling lines should be dedicated pipes.
- Not using golden pipes. While golden waterproof pipes experience backflow just as much as any other pipe, they have four times the capacity, and as such, even when choked with backflow they will still have a reasonable throughput forward. It's a band-aid solution, but it can be enough.
So what should you do?
- Use golden pipes for important cooling lines.
- Use dedicated cooling lines without junctions. If you must supply your carpenter from the same pump, lead a second individual pipe from the pump.
- Make sure the combustion engine only starts requesting water when the pipe is 100% full.
- Use local aqueous accumulators instead of remote pumps.