We are running into a problem where the machine is overheating the water in the exhaust heat exchanger and causing a steam lock in the line. It doesn't matter where we set the temperature, it will run ok for a bit, and then it will just overheat. We tried changing the temp selector dial, the temp sender in the heat exhcanger, and using a different temp control board from another truck that doesn't have this issue. The diverter is operating as it should, opening and closing when 'told'. The light on the back side of the wiring box indicates that even though the temp is high, it is still telling the diverter to open and make more heat. We are wondering if it is a water flow issue. We get pressure, but have no good way to measure flow volume. We set the machine to full speed, turned on the pressure pump, and set it to 500psi, then using short hose with just a ball valve that we normally use for letting the heat off at the end of a job, we filled a 5 gallon bucket in 1minute and 45 seconds. That works to about 3 gallons a minute. We don't use in line solution, just clean water, but that is what the diagrams call that is solution output.