I own a 1991 300SL 24V. Here is my experience. One night after work I came out and started the car. There was an unusual noise from the engine, but it did run. I lifted the hood and immediately recognised the sound of the timing chain being loose. I carefully drove it home ( about 2 miles ) at very light throttle. This sounded like a job for the pro's at the dealer shop. I expected that a gear or link on the chain had jumped due to becoming loose and I prepared myself for an expensive repair. At least it was running so no major damage? Well, it turned out to be the chain tensioner. It is hydraulic and regulated with oil pressure. So the chain hadn't jumped after all. In fact the chain, guides and gears were in excellent condition. The car had about 95K miles at the time. The tech said the because the engine has variable valve timing, the tensioner reacts to keep the chain taught to a spec'd value. The repair was surprisingly inexpensive at just under $300. Good luck with yours.
Resistance is Futile.