Hot water anyone????

I had a heat exchanger once that had a silly filter that needed to be cleaned. When it was gunked up the heat would go way down. I had another one that had these bypass solenoids and if they went bad it wouldn't let the heat build up. Propane heater is the way to go. If it is an issue that is real expensive to fix, you could add a little giant heater to your system.

Also.. It could be something simple like what tool ya using for cleaning? Maybe your flow rate is too high!  Engine rpm's running too low? Make sure your anti-freeze is not low.. This would cause inadequate heat transfer to the liquid heat exchangers.. Is there a dema solenoid on it? It could be stuck in dump mode or may be loose.. Malfunctioning thermostat? Recalibrate or replace.. Exhaust leak in one of the fittings?  And what cmaster said..