100 rpm miminum to start a diesel -- too fast for most people to count if you paint a dot on a fan blade. About four times as fast as most gasoline engines.

If the injection timer is stuck, injection timing will be too fast and the car, when it starts, will snort like a Mack truck. No way to tell but to check the injection timing with a drip tube or pull the timer (its behind the vacuum pump).

The overflow pressure regulator is behind the bolt holding the return line to the IP -- it is either an orifice in the hollow bolt or a check ball and spring. If plugged can cause serious hot hard start problems, also lots of black smoke and excessive fuel consumption.

You may also want to check the valve clearance hot -- the exhaust valves are sodium filled, so grow quite a bit, and if they were dirty when you adjusted them last, can end up with no clearance hot. Guaranteed hard start, what with no glow plugs and no compression! #1 on my 220D closed up to less than 0.005" cold between adjustments!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!