My IP is at a local Bosch shop for a rebuild.

They got the rebuild kit for the internals from Bosch. The diaphragm is an MB part.

They are having difficulty getting the IP governor to seal completely. As I understand it, the new diaphragm is working well but there is a still small vacuum leak at a rod coming near the back.

Without the IP in front of me I'm not quite sure what they're talking about but perhaps someone who's replaced diaphragms might.

Anyway, is this a common problem? Does MB carry the part or is it Bosch specific?

The shop likes using Bosch parts for obvious reasons. However, there was almost a $150 price difference between the Bosch supplied diaphragm @$225 and the MB part at @$85. If the same logic holds this time around, I'd be saving an appreciable sum of money with MB should it be available and could point the shop towards that side of town.

Thanks!

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1974 240D "Boldie" 170K.- New timing chain/freshly rebuilt IP/replaced valve seals/injectors/upgraded stereo/new Bilsteins with Yokohamas/fresh paint and rocker panels plus lots of welds.