If really solid, especially if you hear it cranking, sounds like a spun bearing. And yes, verify that the oil pressure sender is accurate, shouln't run 3bar always as that indicates open circuit IIRC. If not that solid, maybe the vacuum-pump has failed and not yet terminated the engine?

Where are you located? I have the short-block out of my '87 under my workbench.

__________________

Gone to the dark side

- Jeff

My 86 did the same thing. A loud tapping similar to a hammer hitting the block.

It was easy to diagnose on mine though..........
at 70 mph it turned itself into a 5 cylinder!!!

Rod came out both sides of the block and a big chunk of metal came out the oil pan.

4000lbs of Mercedes was airborne for a few seconds.

Pull your pan and check your rod bearings sounds like ones about to come
apart.
Maybe a loose or broken rod bolt?

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes

Maybe a lifter collapsed ?
That's what I was told my noise was.

__________________


Experience : what you receive 3 seconds after you really needed it !!



86 300SDL 387,000? Motor committed suicide
81 300SD 214,000 "new" 132,000 motor
83 300SD 212,000 parts car
83 300SD 147,000

91 F700 5.9 cummins 5spd eaton 298,000
66 AMC rambler American 2dr auto 108,000
95 Chevy 3/4 ton auto 160,000
03 Toyota 4runner 180,000 wifes