Have a 1997 S600, 107,000 miles. Grinding? noise coming from the engine. on 1997 Mercedes-Benz S600

Took to Mercedes friend. Said possible chain wear.
The guide? Only on one side. Used heatmeter, one side warmer by 20 degrees. Will make noise when car is running and will make noise as I speed up.

Asked by for the 1997 Mercedes-Benz S600