Thanks for all the heater suggestions folks. At some point in the future if I keep the van it would be cool to try and fit an espar heater in here, maybe in place of the suburban hot water heater?
Originally Posted by REF
Picture of the plastic part on top of the pump would help to identify, and see weather it’s repairable. Most likely needs to be replaced though
Sorry for the late update. I ended up repairing the pump. The "cap" I was referring to turns out to be the pressure switch. When the pressure drops below a certain point, the switch depresses, the water pump runs until the pressure builds enough to press the button again. The problem was that water was getting past the seal/diaphragm that pushes onto the plastic switch on the other side of it. I cleaned up all the surfaces, added a layer of tape for a bit of extra pressure along the ridge of the seal, bolted it back up and no leaks. Here are some pictures.
But now I've noticed a different problem. The pump seems to be seeping out a salty goo at the metal/plastic interface, lower down on the pump than above. I think this was always happening but might be getting worse. Picture:
Anyone seen this before?