Lesson 1Air intake path: air filter, intake manifold, and causes of restrictionThis section reviews the diesel air intake route from filter to ports, including filter materials, casings, pipes, manifolds, and swirl aids, along with typical restriction sources, measurement techniques, and upkeep strategies for local dust conditions.
Air filter media types and efficiency ratingsFilter housings, pre‑cleaners and snorkelsIntake duct routing, resonators and leaksManifold design, runners, swirl and tumbleSources of restriction, dust and ice buildupMeasuring restriction and service intervalsLesson 2High-pressure injection: common rail vs. pump‑line‑nozzle and mechanical injection pump fundamentalsThis section outlines diesel high-pressure fuel production and regulation, contrasting common rail with pump-line-nozzle systems, and covering mechanical inline and rotary pumps, timing, pressure management, and usual wear or failure patterns in Zimbabwe.
Common rail layout, pressure control and sensorsPump‑line‑nozzle architecture and timing effectsInline mechanical pump elements and cam profileRotary/distributor pump operation and advancePressure waves, line length and injection shapingTypical high‑pressure leakage and test methodsLesson 3Intercooler function, pressure loss, fouling and cleaning considerationsThis section clarifies intercooler roles and operations, comparing air-to-air and air-to-liquid types, tackling pressure drops, fouling, leaks, cleaning approaches, and charge-air temperature effects on power and emissions in hot Zimbabwean climates.
Charge‑air cooling benefits and heat transferAir‑to‑air versus air‑to‑liquid intercoolersPressure drop, flow balance and sizingOil fouling, soot deposits and leak pathsCleaning methods, flushing and drying stepsTesting for leaks and performance lossLesson 4Ancillary components: EGR overview, PCV/ventilation basics, sensors relevant to diesel (MAP/MAF, coolant temp, oil pressure)This section overviews key supporting diesel parts, including EGR and crankcase ventilation, plus essential sensors like MAP, MAF, coolant temperature, and oil pressure, and their interactions with the engine control unit in local setups.
EGR purpose, flow control and cooler issuesPCV and crankcase ventilation arrangementsMAP sensor role, mounting and failure modesMAF sensor types, contamination and testingCoolant temperature and oil pressure sensingSensor data use in diesel ECU strategiesLesson 5Cooling system: radiator, water pump, thermostat, coolant types and causes of overheatingThis section addresses diesel cooling system design and function, including radiator, pump, thermostat, coolant formulas, flow routes, and frequent overheating triggers, plus checks, tests, and preventive care suited to Zimbabwean heat.
Coolant flow path and heat transfer basicsRadiator, fan, shroud and airflow managementWater pump design, drive types and failuresThermostat operation, testing and replacementCoolant types, mixing rules and corrosion controlDiagnosing overheating and hot‑spot conditionsLesson 6Injectors: nozzle types, spray patterns, wear symptoms, and leakage effectsThis section spotlights diesel injector build and roles, including nozzle varieties, spray patterns, opening pressure, wear and coking signs, leakage impacts on emissions and power, and fundamental test and servicing methods in workshops.
Pintle, hole‑type and multi‑hole nozzlesSpray pattern, atomization and penetrationInjector opening pressure and pop testingNozzle coking, erosion and seat wearInternal leakage, dribble and misfire effectsBasic cleaning, replacement and codingLesson 7Turbocharger components and operation: turbine, compressor, wastegate/variable geometry basicsThis section describes turbocharger structure and function, including turbine and compressor airflow, bearing setups, wastegate and variable geometry controls, boost caps, and failure indicators tied to lubrication or overspeed in Zimbabwean use.
Turbine housing, wheel design and energy useCompressor maps, surge and choke regionsJournal and ball bearings, seals and coolingWastegate actuators, control lines and tuningVariable geometry vanes, actuators and sootTurbo failure modes, inspection and protectionLesson 8Fuel delivery system: fuel tank, lift pump, primary and secondary filters, and water separatorsThis section outlines the low-pressure fuel delivery route, from tank and pickup to lift pump, filters, and water separators, stressing contamination prevention, air entry, restriction diagnosis, and standard service steps for local fuels.
Fuel tank design, pickups and return routingLift pump types, priming and failure signsPrimary and secondary filter functionsWater separator design and draining practiceAir leaks, suction restriction and cavitationService intervals and contamination controlLesson 9Lubrication system: oil types, oil pump, galleries, bearings and oil filter functionThis section elaborates diesel lubrication system layout, oil types and additives, pump varieties, galleries, bearings, and filtration, detailing oil pressure creation, monitoring, and upkeep to avert wear and overheating in dusty environments.
Engine oil grades, base stocks and additivesOil pump types, drives and pressure regulationMain galleries, branch feeds and priority circuitsBearing lubrication, clearances and coolingOil filter types, bypass valves and serviceLow oil pressure diagnosis and common causes
