Tapping/Lifter/Injector???

[BrierS]

Started removing parts from my '87 300TD. Had leaking intake and old style vacc. pump to attend to. While I was at it, I wanted to try and locate the cause of a tapping. Though it sounds like a lifter (or two) it has me baffled. I hear it primarily above 1,600 RPM and under load (hill, etc). The noise did not start until after I had changed to Mobil-1 syn (diesel). Since, I have changed the o-rings on the filter stem. Using my stethoscope, the noise seems to be either 4th or 5th cyl. I would love to try checking the lifters as described (after the engine is hot) but it is w/o intake, etc.

Anyone suggestions as to checking the lifters with the engine below 30 degrees? Is it possible the noise is an injector (remember noise is primarily with the RPM level up and under load)? Thanks in advance.
Steve

[sixto]

Crack the lines to the injectors one at a time so you can isolate the noise to a particular cylinder. If the noise doesn't go away when you're done, it's very likely a soft lash adjuster.

Sixto
95 S420
87 300SDL
83 300SD ... $950, see cars forum