Oilslick:

Does the glowplug lamp work correctly (ie comes on for a while, then goes out and stays out)? If not, you have at least one bad glowplug.

Easy check is to check for 12V on each glowplug while operating, and to check the resistance of all four (you can pull the plug off the relay to check resistance).

If the glowplugs check out, and the valves are OK, time for the leakdown

To perform, you need to pull either the injectors or glowplugs, then add compressed air to the cylinder AT TDC FOR THAT CYLINDER. You must be at exactly TDC with both valves closed. Close won't work, the engine will motor to BDC and a valve will open!

Hiss in the intake, intake valve leaking. Hiss in the exhause, exhaust valve leaking. Hiss in the crankcase, rings.

I would advise against adding oil and repeating a compression test to check for worn rings -- it is possible for the oil to ignite, and this will blow up the compression gauge, usually.

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!