W124 cooling system pressure

[cele_997]

the vehicle: 1995 Merc E320. 159 000 miles.
issue: I am suspecting that my w124 is developing too much pressure in the cooling system. I have owned for four months and I have spent about $1000 on replacement parts for the cooling system.
1) when I bought car, it was mixing cold AC air in center vent with hot air on outer vents. Peachparts forum helped to figure out duo-valve issue. fixed
2) about a week after that it started mixing windshield washer fluid with coolant - i suppose the duo-valve was now actually working so coolant was now going thru the heater element in the windshield washer reservoir tank (maybe that's why the prev owner didn't change the duo valve..). I noticed the coolant level had shot up one morning - and then noticed that the windshield reservoir was empty - that and the fact that the coolant in the coolant overflow tank was now orangish-purplish - strange color. I replaced the heater element in the windshield reservior tank and that worked for all of two months and then same problem. I don't need heated windshield fluid in texas so I am planning on doing a by-pass job.
3) my overflow tank developed a crack and started leaking about two weeks after I had replaced the initial heating element in the windshield reservoir. I replaced the tank - suspected the high pressure issue back then and got a new reservoir cap. I fit rather tightly but then i thought that all new caps should fit tight - right???
4) the elbow joint that goes into the radio from the overflow line to the reservoir tank snapped - i just found it leaking during my morning fluid check. thanks the peachparts, i didn't have to buy the whole radiator - i replaced the elbow joint and that was that...or so i thought.
5) in a seemingly unrelated incident, my fan clutch bearing seized, the shaft heated up and snapped of and the fan went partying and met the main crankshaft pully - no radiator damage - or so i thought. I replaced fan clutch bearing housing, fan clutch, fan, fan belt
6) this week, i found a pool under my car in the morning, it was coolant. after a short drive, i pulled over and saw the leak coming from the radiator side - the same side on which the elbow joint goes - just a crack in the radiator side - so I am now looking at a radiator job.

my question to the forum is: is it possible that my cooling system is building up too much pressure and thus various components are now taking turns in failing. the engine never overheats, its starts right up, idles well so i don't think i have a blown head gasket pushing pressure into the cooling system. I have not replaced the water pump and from the slight wear on the bearing, I doubt that the waterpump has been replaced lately so I dont think its the case of a new water pump suddenly pushing pushing too much pressure on old components.
HELP! - what else can i check for? before i replace that radiator, I must find whatever is causing cooling system components to break. if i don't, the next thing to go will probably be the heater elements.
Any ideas will be appreciated