OK, why did my 115 240D go through ANOTHER vacuum diaphragm in less than 25,000 miles?? Was this cheap parts, bad luck, or is there some systemic problem I should be looking for?
The diaphragm is cracked at the perimeter of the outside support washer, just like the first one. (Which, by the way, lasted for 120,000 miles and 25 years -- 500% better life than the replacement.) I'm sure I assembled everything properly, but in case someone's intimately familiar with this, maybe you could verify that the small back-up washer goes on the OUTSIDE of the diaphragm and the large one goes INSIDE? And yes, I did make sure to put both chamfered washer edges against the diaphragm.
If it's any clue, I also lost one of the replacement poppet valves. The valve's plastic disk just shattered. Fortunately, I saved the originals, so one of those is back in there now. Though there were plastic bits from this blow-out floating around, none of these had anything to do with the diaphragm's demise; it's clearly a wear-through problem at the washer edge that did it in.
So, my good Sherlock(s), what's the root problem here?
Thanks in advance!
Larry