Peter:

Most likely you have a bad injector(s) -- they can spray almost sideways when the pintle gets chipped, and you can actually ruin a head by burning out the pre-chamber. You have to run it that way for a LONG time, but if you are burning glow plugs, I suspect a bad nozzle.

Testing is usually free at any diesel injection service -- there will be one somewhere near you. Just call. Nozzle replacement and pressure setting will run about $50 each.

There are two other causes of knock on diesels, at least MB diesels -- a loose chain from excessive stretch or a bad tensioner, worst on a warm engine at about 45 mph and a stuck injection timer that gives fast timing at low speeds. The later will cause knock and "snort" like a big truck with black smoke at low speed and excessive smoke at high speed if it isn't stuck at full advance.

I suspect the only way to check the centrifical timer is to remove it and check for free rotation against the springs. If one or more of the spring are broken or collapsed, you may have proper static timing but too much advance at low speed.

Peter

PS -- got the timing on the Volvo right at long last -- very little smoke and mucho power -- not as much as the 300D, but enough it is a pleasure to drive again!

__________________
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!