Mercedes-Benz M104 engine - Wikipedia
The Mercedes-Benz M104 is a straight-6 automobile engine produced from 1989 through 1999. It has a double overhead cam design with 4 valves per cylinder. It replaced the M103 and was replaced by the M112 V6 starting in 1997. The M104 continued in production until 1999 where its last use by Mercedes-Benz was in the W140 chassis.