Follow-up--- After a couple cycles of on and off and adding additional fluid, the last 5 mile test ride car stayed cool, well under the 100c mark. I think IT'S FIXED.................. WOOOOOOOOOOOHEEEEEEEEEEE!!!!!!!! (no party yet till later highway test)
The collapsed hose was the engine vacuum that wanting more fluid....still going to replace puffy elbow hose....
I made a homemade cooling system pressure tester with a bicycle foot pump (with gauge) connected to the overflow tube going to the radiator (used rubber gas hose that fitted inside overflow tube at one end and slipped over foot pump air nipple). I just blocked the overflow hose nipple at the overflow reservoir with a short piece of hose, clamped to nipple, and with a bolt screwed in open end of hose, as a stop. This test is great because it tests the cap too! MB's factory pressure tester has a modified radiator cap that is used and you have to remove your existing cap to test.
As much as I'm learning about my MB, I hate to even think about selling it.... This car cost $54,000 new in 1994 (I paid a fraction) and drives smoother than new. I tried the newer series E models 96- later and they don't drive/feel like the original W124 series or older MB classics.....also the design of newer MBs you have to see MB logo to know it's a Mercedes... the classics stand out as MBs without a doubt....
I'll post a follow-up after highway test....