John:

Sounds like an injector to me, not a lifter. Switch to a good synthetic (if you notice, they are the only oils at the auto parts stores actually rated for turbocharged diesel use) and see what happens.

I'd also get some RedLine or similar diesel treatment and see if that helps, too. Put the entire bottle in a fresh tank of fuel. If it does, but the problem comes back you many have a bad injector nozzle.

Diesels are amazing -- they will run and run and run. Some idle knock is to be expected -- some engines do and some don't, and some fuels are worse than others. I'd only really get excited if you also have a rough idle or excessive smoke or power loss.

Peter

__________________
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!