Date registered: Aug 2012
Vehicle: 74 450 SEL, 78 300D, 99 Ford 7.3 turbo
Location: Douglas, Arizona
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B]BLACK SMOKE IS CAUSED BY 1. EXCESSIVE FUEL, 2. INSUFFICIENT OXYGEN, AND 3. LATE TIMING.[/B] All these can be caused by blocking of orifices in bottom of precombustion chambers (PC's)! How does a home mechanic comply with Equipment Repair Notices from the Highway Patrol? Take the PC's out, drill out holes (if clogged) with .110" (#35) drill bit, reinstall for a most dramatic improvement. I have now done this to 2 300D's, one turbo and mine, NA. Results were dramatic! I now know of 4-300D engines with less than 300k miles that were junked for loss of power and excessive smoke. One was rebuilt, and the only real problem noticed was, you guessed it, nearly completely blocked PC orifices. Vehicle histories indicate preponderance of in-town slow speed driving for many years. I'll bet the orifice cleaning procedure is well known at the MB dealerships: Very little cost for great improvement and high repair bills! This repair does not require new parts, other than PC gaskets and injector heat shields ($30 total), if you want to be picky. Get the tools and do it yourself! The job takes 2-4 hours, depending on you level of ineptitude.