[bushpilot]

Originally Posted by porky69

On my Haulmark ( Freightliner) if I fill one side right full by the time I slide the hose underneath to fill the other side (my favorite station is only single side) the first tank will have dropped a couple of inches, even with the engine off. All of the big trucks (Peterbilt, Kenworth, Western Star, IH) I have driven were the same.

There are no pumps just a Tee fitting with equal length hoses (very important) and it works on the siphon principle.

porky our coach (also a Haulmark) is a Columbia cab/chassis ('04).

if tank balancing works as you say (and i don't doubt yours does) - i haven't seen that in our coach....in fact i would expect balancing to happen ALL the time - including when running down the road...which doesnt explain why my drivers side tank can get so low while the passenger side isn't (so low).

IN FACT...if balance occurs as you say, then wouldnt a generator (which is only getting its supply and return on from the passenger side) potentially drawl from BOTH (balanced) tanks ???

Ive run the generator (after topping my tanks up) pretty constant on/off while tailgating for 3 or 4 days and only saw my passenger side level drop.