Document ID: MB-OM422-WM-01
Revision: 2.0
Applicability: OM422.90, OM422.91, OM422.92 (Naturally Aspirated & Turbocharged variants)
Vehicle Applications: Mercedes-Benz NG/SK heavy trucks, Unimog U 1300/U 1550, Freightliner (FL-Series), industrial power units.
Released in 1980, it was the first Mercedes diesel for heavy commercial vehicles to feature an intercooler (in its "LA" variant). Indestructibility: om422 engine workshop manual
Service intervals for oil and fuel filters, and procedures for disassembling oil pumps and coolers. Torque Settings: Warm engine, drain oil completely, replace filter and
By investing in the OM422 engine workshop manual, mechanics and engineers can ensure they have the information they need to work efficiently and effectively with this exceptional diesel engine. Released in 1980, it was the first Mercedes
| Symptom | Possible Cause | Correction | | --- | --- | --- | | Hard start, white smoke | Low compression (worn rings/valves) or retarded injection timing | Perform compression test; check timing marks on injection pump drive. | | Knocking noise, worse when warm | Pistons contacting pre-chamber (carbon buildup) or worn big-end bearings | Remove injector, use borescope to check piston crown; inspect rod bearings. | | Oil pressure low (<0.8 bar at idle) | Failed pressure relief valve or worn main bearings | Replace relief valve spring; check main bearing clearance. | | Black smoke under load | Over-fueling (stuck injector) or restricted air intake (turbo wastegate stuck closed) | Test injectors; check turbo actuator and air cleaner. |