I would contact the member in this thread to have your injectors rebuilt..

http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/338033-fs-brand-new-injector-nozzles-injector-service.html

It seems like the noise disappears as you rev it....I would do a valve adjustment, rebuild injectors, new filters line, primer pump and I would upgrade to pencil glow plugs..

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