While I agree that one flush will do a better cleaning job on the PS system than one drain/suction/refill method, I still don't think a flush is a good way to go if it causes the PS pump to grind. Wouldn't you agree with that? It's been my experience with the W210 system that any air trapped in it will let itself be known through a nasty grinding noise. I have found the W123 system a lot more forgiving. I also think that if one simply replaces the fluid every 30K miles or so, then it's just as good if not better than a flush every 150K miles. I once tried the flush on my 240D after having done the simple drain/suction/refill method once or twice prior to the flush. Only clean fluid came out and I almost ran the pump dry. The flush isn't worth it IMO.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL