Very interesting! I am just doing away with pumps all together. Won't order them on a bus and won't replace them when they leak. I put three Bergstroms on a single bus in less than a month. When the dealer sent it to the company for warranty they sent it back saying it was not leaking. What the company didn't know was the BB traveling parts man happened to be at my shop & watched me take it off. He saw the leak!! I think my dealer, Central States, just ate the cost though
I remove all the pumps and the cable operated valves from heater system on all busses except anything with a vt365 or 6.0 powerstroke. The water pumps in those just dont work well enough without a booster pump.
We had quite a few problems with pumps, but they've really "dried up" (ha ha) since about 6 years ago. We bypassed several of the problem children and haven't had any driver complaints. As long as the switch still lights up...
"Growing old is mandatory. Growing up is optional."