I hear an extra knock sounds like #3,4 injector and IP has small leak on top around #3,4 line but connections at line to pump seem tight. I have smoke at cold startup, and poor mileage. Any troubleshooting advice will be appreciated.

Your symptoms appear to be leaking delivery valve seals on the IP. The replacement of the o-ring is necessary. Sometimes the copper washer is also replaced. There is a special splined socket tool and torquing procedures required before you tackle this project.

What's the cost of these parts?

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I'm not a doctor, but I'll have a look.

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Thanks for responding. Is this information available on the MB service disk? Or is there an outline available for the IP service?

I see on the MB service disk:delivery valve holder (35nm), compression spring and copper seal (replace),delivery valve (rinse in fuel),delivery valve carrier (make note of installed position), O ring (oil before assembly). Does this sound right? Is there a kit to rebuild this section of the IP for all the seals? Or should I repair only what is necessary? I'll take a look at Phil"s page to see if some answers and costs are available.