Some of the major diesel engine manufacturers include:

1. Cummins: An American company that produces diesel engines for a wide range of applications, including on-highway trucks, buses, and off-highway equipment.
2. Caterpillar: An American company that produces diesel engines for heavy equipment, power generation, and marine applications.
3. Detroit Diesel: An American company that produces diesel engines for on-highway trucks, buses, and off-highway equipment.
4. John Deere: An American company that produces diesel engines for agricultural and construction equipment.
5. Volvo Penta: A Swedish company that produces diesel engines for marine and industrial applications.
6. MAN: German company that produces diesel engines for heavy commercial vehicles, power generation and marine.
7. MTU Onsite Energy: German company that produces diesel engines for power generation and marine propulsion.
8. Deutz AG: German company that produces diesel engines for a wide range of industrial and mobile applications.
9. Yanmar: Japanese company that produces diesel engines for agricultural and construction equipment, as well as marine and power generation applications.
10. Daewoo: South Korean company that produces diesel engines for a wide range of industrial and mobile applications.

There are many companies and manufacturers around the world that produce diesel engines for a wide range of applications, including automotive, marine, power generation, and industrial uses. Some of the additional manufacturers include, but not limited to:

• Scania
• DAF
• Mercedes-Benz
• Renault
• Iveco
• Perkins
• Isuzu
• FPT Industrial
• Mitsubishi Heavy Industries
• Wärtsilä
• Rolls-Royce Power Systems