1.   The intake valve was jammed open.

2.   Bleeding the system may not work if the intake valve is not working.

3.   A DOHC engine has two cams over each bank of cylinders, typically one for the intake valves and one for the exhaust.

4.   A radiator that is perfectly level or pitched away from the intake valve will trap water so steam cannot enter.

5.   But further, it also controls lift and duration of the two intake valves on each cylinder.

6.   During the intake stroke of an engine, as the piston is moving downward, the intake valve opens, allowing fuel and air to enter the cylinder.

7.   If the intake valve is not working, the system should shut down by itself if the water gets too low.

8.   If in doubt, have a plumber check the intake valve and anything else that seems amiss.

9.   In a nutshell, fuel and oil deposits build up on the backs of the intake valves interfering with the correct breathing and performance of the engine.

10.   New valve controls eliminate the mechanical throttle, improving engine response, and the intake valves are infinitely variable for peak efficiency.