Looking at 2 ML350’s. 1st is 2007 ML350 with 131000 miles and bad transmission. 2nd is 2008 with 150000 miles and no reported problems. My main question is, which year engines had the timing chain issues?

 

This document will tell you what you need to know. Focus on engine numbers and that will tell you what engines are affected and what isnt, at least officially. You'll need the engine number from the cars you're considering.

 

An '07 with a bad transmission has no value, the cost to repair is more than the car is worth. The '08 if it's clean is worth around $5k, but have a pre-purchase inspection done at a dealer, it probably needs $4k worth of work done to it.

 

Both the 07 and 08 have potential engine issues. The 08 transmission also has potential for going bad in the near future. You want to be looking at 09 and newer to avoid both the early M272 and 7G-Tronic issues unless you can get records of both engine and transmission rebuilds.