Thanks for the info about the tensioner. That sounds like it was a relief to get fixed. This engine has no oil getting to the cams and lifters, that's why the noise is so bad. All the lifters bled down when the oil pressure was lost. The canister would have been wet from recently drained oil, but it looked like it had drained for several days, even right after running the engine. There was no oil dripping from the filter.

I don't know if it's toast, but it ran for awhile with no oil pressure. I advised her to tow it to a MB specialist before it starts knocking.