Details of installation of glow plugs on diesel engines (using a 4-cylinder engine as an example)
1. Warm up the engine to normal operating temperature (80°C).
Attention! The spark plugs should be removed only after the engine has been fully warmed up!
2. Remove the air distributor trim panels (2) and cylinder head covers (1).
3. On 628 series engines, remove the air cleaner (see Chapter Fuel and exhaust systems).
4. On 612 series engines, disconnect the return line to the high-pressure fuel pump from the fuel line.
5. Disconnect the electrical wiring (3) from the glow plug to be removed.
6. Remove the spark plug (R9).
7. Using a special cylindrical brush of suitable diameter, clean the spark plug niche.
8. Installation is carried out in reverse order.
(Original material on the website: «www.mercedesman.ru»)