The red portion below may be relevant to this post
ML320 2002
Now??? Here is the update:
I fortunately got hold of chap up the road to come have a look see and here is what was discovered:
I did not have information other than what was said on the sheet of paper which came with the water pump; take the screw cap off the antifreeze water filler bottle or reservoir of the car fill it up and leave the cap off, start the car so as to assist with getting air locks or air out of the water system out the car while the car is running up to operating temperature - which I did but experienced the problems mentioned in the immediate post above. What the chap did do different is that he revved/accelerated (at first periodically about 3000 rpm then later on keeping it at 3000 rpm for longer periods of time, the thermostat opened during these procedures and the flow of water increased throughout the system unlike when I was doing it by just letting it idle and thereby expelling any air in the entire system with the thermostat open. What was discovered further was that the top radiator hose leading to the thermostat housing was collapsing because of a huge air gap in the system and also that I need a new hose especially in that section.
Also discovered which is not necessary relevant to the problem I was having and what Doc has mentioned in other posts was that the air filter was in serious need of replacement (which I am embarrassed to admit really am this is a silly oversight on my part), also (again not necessarily relevant to my immediate problem above) that the clutch assembly needs to be replaced showing play and wear and that even though antifreeze was more than a 50/50 ratio or rich blend of antifreeze to water which in turn raises ones boiling point in summer it would have no real benefit if the fan assembly or viscous fan/ clutch fan is running at 1/2 its speed.
The chap then said without checking or even looking doesn’t forget to re-tighten the cables to the battery, especially the red/live battery cable and sure enough it was loose. The chap then went on to say that this is a great vehicle and strong engine and will last for a long time, good coil pack, the only thing negative is the front axles (if this includes the ball joints, I don't know) and the Mass airflow sensor and the temp. Sensor may have to be replaced from time to time.

So I will be purchasing the 3 new parts as soon as possible, especially the
hose above asap as he said that the hose will probably swell up and explode pretty soon.

But here is where I fall short:
How does the above problem find marry up with what appears to be an electrical fault??? anyone??
My guess is that had this been an older vehicle without sensors I would have driven without knowing any better, but the sensors sensed no water flow and put the vehicle in limp mode or warning mode of possible engine failure and thus would not start?