w124 reservoir tank overflow hose; NYS emissions failure
 

If this hose, which becomes rock hard after time and heat, develops a crack, such as at the end of the nipple where the hose makes a sharp turn to begin its path to the fender wall, would that crack and potential leak contribute to the engine temp rising quicker than if this hose were new and intact? Just wondering, because the guy who did my NYS emissions inspection told me the car initially failed and overheated, then said it passed after he added some antifreeze (which naturally was the wrong kind, green). He aattempted to charge me an additional 40$ labor plus $16 for the antifreeze,which I refused to pay after explaining to him that MB takes only zerex gr5. And this is a shop that knows me and my family; I can only imagine how they treat strangers and those that don't know their vehicles.

That hose being broken should have no effect.

Was the reservoir completely empty?

How is your fan clutch, and the aux fan(s)?

The reservoir level is OK, and aux fan atypically cuts in at 105 degrees or so, and cools down the engine. I have an 87 300e and it never gets that hot; I'm thinking of swapping out the fan clutch just to see if it changes anything. Otherwise, I 'm thinking maybe a weak water pump us causing the relatively quick rise of engine temps.

Can you hear the fan making a roaring noise when the engine is hot, after you start off from a red light? You should be able to hear it, then it quietens down as the temp drops and the clutch disengages.

Defective fan clutch is a good possibility but exactly how could you have a "weak" water pump?