BuildCraft 4.02 (39) / MC 1.6.2
Also tested with Buildcraft from bithub today with MC 1.6.4 / Forge 1.6.4-9.11.0.881

When pumping an oil spout, once the pump reaches an oil block that will be replaced by a water source block (at the surface of an ocean) the pump will no longer move its tube down and seems to be caught in a loop. I'm just learning modding/java but it seems like it gets stuck in the rebuildQueue method.

This block removes correctly

The pump seems stuck on the water surrounding it here and will not move down to resume pumping the oil spout

Workaround is to isolate the oil spout from the surrounding ocean with blocks, so that the removed block is not replaced with a water source block.

Yeah, I can confirm this, but anyway it better than pumping water in.

yes those pumps are a bit bugged

=/