Is performing the bleeding procedure really necessary for the cooling system????
 

O.K. I drain and fill the (so call life time) cooling fluid. I done this many times on various cars for years. What I always did was just fill up the radiator as much as I can and drive it around the block let it cool down and add some more fluid and then drive it for a few miles and add some more fluid and I am done. I find with this method the cars never even comes close to over heating and I add less than 1/2 gallon of fluid (I figure 1/2 gallon short will not harm the car). And then I find that I don't have to add any more fluid for months if not years.

But recently I learn that there are procedures to bleed the coolant system and some cars even have bleeding screws.

So my questions is? Has what I been doing for years sufficient? I think it is. My reasoning is if there is air in the system the air would rise to the top which is the radiator cap.

What do you folks think???

Depends on the design of the particular engine.

On the whole cast iron heads (such as the OM61X engines) are less likely to have trouble with your existing method. Aluminium alloy heads, however, ought to be treated a bit more carefully. Some vehicles actually have radiator caps that are lower than the highest point on the engine!

But if a system has bleed screws then use them!

I drill a small hole in thermostat to make bleeding easy

AFAIK, all Mercedes engines are self bleeding. Certainly 123,124,210 and. 201 cars are in my experience. When I hear about some of the nutty procedures employed, from hanging the front of the car on a hook to pressure filling, my assumption is that either the car has a clogged radiator or the owner has a brain fart. Your procedure works fine, as long as you are sure to run the heater.

Cars are out there which have air bleeds, and require special fill procedures. For example, Porsche 944, Jaguar XJS, Corvettes with reverse flow cooling, probably more. So check rhe FSM if you are unfamiliar with the vehicle.