BMW: E36 overheating, coolant systems, coolant water

Question
My 1994 316i  300 000 KM BMW have interrupted overheating problems before it seems the engine was running below the middle mark and took some time to reach its normal temp in the middle.

A few days ago suddenly it overheat in the red, after investigating all hoses I found the plastic fitting clamping the hose to the engine block to be broken, (WATER RETURN LINE) on rectifying the problem it when fine for 2 days, then again overheat, then removing the thermostat, now summer here. Then fine for a day then today it went to the 2 mark from the middle to the red.

My plan of action is the flush the system with a wynns product and replaces the coolant water ratio.

What is the correct method of bleeding the water system?

Any other suggestions or method to diagnostics the problem?


Answer
Jan,
 I will try to help, but I am not familiar with the year or model of your car.  We did not get the 316i here in the USA, and I know more about 1991 and earlier cars.  BMW's are tricky to get the coolant systems right.  So far I've had more coolant related questions than any other.  If you have opened the system to outside air, then chances are you have air in the system.  On the US models there is a bleeder valve at the radiator, that you open as you poor in the coolant, the air comes up through this valve.  I read that some of the older cars (before 1996) do not have this.  Look on the Internet for a site dedicated to the 316i, and they should be able to direct you.
 Also, be sure that your fan clutch is working properly, often this is overlooked as a possible problem. but with 300,000km you might need one.  To test it, start the car and try to stop the fan with a rolled up news paper.  the fan should stop with no problems.  Warm the car up, then try it again, it should be much harder to stop.  

 IF you have no luck, let me know what you have done, and I will try some other things.
 
 This is on a vehicle I am not familiar with, it's obviously from another country, which has different regulations and safety standards.  The US BMW's are different from their European counterparts.

 Thanks Jan,
 Josh F.