Noisy idle 87DT

Here comes,
I am sure there have been numerous posts on the MB noisy idle (especially prior to 1987, I assume). However, I had a hard time trying to find a brief description of fixing the noise rpoblem for my 124. It has 210 KMi, engine is in nice shape (high, uniform compresssion, no blowby, no block-heater during cold Mid-West winters). I know for a fact that the idle is way too noisy (could hear the clank-clank from 100 yards). Any suggestions? I've heard that a diesel engine with hydraulic (spelling?) lifters should be cleaned on a regular basis.
Thx.