strange noise, coolant valve cycling on and off? My '05 has developed a strange noise from the engine compartment. It sounds like a pump or valve cycling on and off, about once per second. It comes up seemingly randomly and might last for a few seconds or near 30 seconds, engine on or off. It has been happening for the last 20k miles or so. I connected my Autoenginuity scan tool, and cycled the water pump and water control valve(s). It's not coming from the water pump, and the noise comes up after cycling certain water valves. No MIL for a failed coolant flow control valve. Any thoughts?