Lesson 1Air intake path: air filter, intake manifold, and causes of restrictionThis section examines the diesel air intake path from filter to ports, including filter media, housings, ducting, manifolds, and swirl devices, plus common restriction causes, measurement methods, and maintenance strategies for dusty Botswana roads.
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 explains diesel high‑pressure fuel generation and control, comparing common rail and pump‑line‑nozzle, and detailing mechanical inline and rotary pumps, timing, pressure control, and typical wear or failure modes in local use.
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 explains intercooler purpose and operation, comparing air‑to‑air and air‑to‑liquid designs, addressing pressure loss, fouling, leaks, cleaning methods, and how charge‑air temperature affects power and emissions in hot Botswana 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 reviews key ancillary diesel components, including EGR and crankcase ventilation, plus critical sensors such as MAP, MAF, coolant temperature and oil pressure, and how they interact with the engine control unit in Botswana vehicles.
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 covers diesel cooling system layout and operation, including radiator, pump, thermostat, coolant chemistry, flow paths, and common overheating causes, plus inspection, testing, and preventive maintenance practices for Botswana 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 focuses on diesel injector construction and function, covering nozzle types, spray patterns, opening pressure, wear and coking symptoms, leakage effects on emissions and power, and basic test and service practices in local settings.
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 explains turbocharger construction and operation, covering turbine and compressor aerodynamics, bearing systems, wastegate and variable geometry control, boost limits, and failure symptoms linked to lubrication or overspeed in Botswana.
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 describes the low‑pressure fuel delivery path, from tank and pickup to lift pump, filters and water separators, emphasizing contamination control, air ingress, restriction diagnosis, and routine service procedures for Botswana 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 details diesel lubrication system design, oil grades and additives, pump types, galleries, bearings, and filtration, explaining how oil pressure is generated, monitored, and maintained to prevent wear and overheating in dusty conditions.
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
