STIHL 028AV SUPER Service Manual
Overview and scope
Purpose of the manual is to provide clear, actionable guidance for the inspection, maintenance, and repair of the STIHL 028AV SUPER chain saw. It outlines the recommended procedures, tools, tolerances, and fault-finding steps necessary to restore the equipment to safe, reliable operation. The document serves as a technical reference for proper servicing, including disassembly and reassembly sequences, adjustment procedures, and routine maintenance schedules. By detailing standard procedures and common troubleshooting scenarios, the manual supports consistent workmanship and helps reduce downtime during field repairs.
Intended audience and prerequisites identify the reader as a professional technician or experienced hobbyist with a foundational understanding of small engine mechanics. Prior exposure to two-stroke engine operation, carburetion basics, ignition systems, and exhaust considerations is assumed. Readers should have access to the appropriate safety gear and workshop equipment, such as a torque wrench, calibrated gauges, and standard hand tools. The material is designed to supplement factory service bulletins and parts catalogs, providing practical guidance that complements OEM specifications.
Safety and compliance notes emphasize the critical importance of following established safety practices to protect personnel and equipment. The manual references proper lockout/tagout procedures, appropriate PPE, ventilation for fuel handling, and adherence to local environmental regulations when disposing of spent oils and filter elements. It also highlights the necessity of using manufacturer-approved parts and adherence to torque specifications, temperature limits, and timing marks to prevent inadvertent engine damage. Compliance with regional emission and noise standards is noted where applicable, along with guidance on safe testing and startup procedures to minimize the risk of injury.
The STIHL 028AV SUPER is a mid-sized, professional-grade chainsaw designed for demanding cutting tasks in forestry, construction, and utility work. It combines robust engine performance with a compact, balanced frame to reduce operator fatigue during extended use. This model is renowned for its reliability in harsh environments, where >durability< and consistent power output are critical. Operators can expect precise cutting control, smooth throttle response, and dependable cold-start performance in varying weather conditions. Overall, the 028AV SUPER is built to deliver steady performance across a range of wood densities and cutting scenarios while maintaining manageable handling characteristics.
Technical specifications and capabilities establish the 028AV SUPER as a versatile tool suitable for professional users. The engine is designed for strong torque with a reliable ignition system, enabling efficient startup and steady engagement under load. The air filtration system provides sustained protection against dust and debris, which is essential for maintaining performance in challenging environments. This model supports standard maintenance intervals, with accessible service points for spark plug, air filter, and fuel system checks. When operated within its designed parameters, the saw delivers predictable power delivery, balanced with vibration control to support operator endurance over long work sessions.
Key components at a glance include the anti-vibration handles, which mitigate user fatigue during extended operation and improve control accuracy. The bar and chain assembly is designed for durable trimming and cutting with efficient chain lubrication to minimize wear. The carburetor and fuel delivery system are tuned for reliable performance across temperature fluctuations, ensuring consistent starting and smooth throttle response. Cooling airflow and exhaust routing are optimized to prevent engine overheating during prolonged use. Easily accessible filters, the muffler, and the spark plug area allow for straightforward routine maintenance, which helps extend the service life of the machine and maintain peak performance in demanding work environments.
Tools and safety equipment required
When performing maintenance or repair on the STIHL 028AV SUPER, assembling a complete and well-organized toolbox is essential for both safety and efficiency. Begin with personal protective equipment (PPE) that matches the tasks at hand, including safety glasses or goggles to protect your eyes from flying debris, and hearing protection to guard against prolonged exposure to noise from power tools. It is also prudent to wear cut-resistant gloves when handling sharp components or cutting tools, and sturdy footwear to prevent injuries if parts are dropped. A long-sleeve, flame-resistant work shirt can offer additional protection when dealing with hot parts or caustic substances. Keep a first-aid kit, a fire extinguisher suitable for electrical and chemical fires, and a spill kit readily accessible in the workshop as part of a comprehensive safety plan.
Essential hand tools and power tools form the core of a dependable service setup. The basic hand tools should include a metric and standard screwdriver set, an assortment of Allen wrenches, socket wrenches with a full range of metric sizes, needle-nose pliers, snap-ring pliers, a torque wrench with appropriate ranges, and a set of feeler gauges for precise clearances. A soft-faced mallet helps avoid marring delicate components, while a magnetic parts tray keeps fasteners organized. For power tools, a quality impact driver, a variable-speed rotary tool with cutting and grinding bits, a small air compressor with a regulator, and an appropriate shop vacuum are valuable for efficient cleaning and debris removal. Ensure all power tools have intact power cords, guards in place, and up-to-date safety certifications before use on any service task.
Specialized service equipment enhances the precision and reliability of repairs on the STIHL 028AV SUPER. This includes a calibrated torque wrench appropriate for small engine fasteners, a ring and notch feeler gauge set for accurate carburetor and timing adjustments, a dial indicator for measuring component runout, and a micrometer for precise bore or cylinder work. A quality carburetor synchronizer and a fuel system pressure tester can greatly aid in diagnosing and correcting fueling issues. A parts tray with labeled compartments helps manage small components, while a magnetic pick-up tool and calibrated calipers support accurate measurements during disassembly and reassembly. For safety and cleanliness, a parts cleaner, solvent, and lint-free wipes should be used to remove grease and residue without leaving fibers that could contaminate critical passages.
In addition to the listed tools, organize a dedicated work surface with adequate lighting and a clean, non-slip mat to prevent small parts from rolling away. Keep a reference manual or service guide readily available, and consider maintaining a laminated checklist to ensure all steps are performed in a consistent sequence. Always verify that the engine is disconnected or safely isolated from any ignition source before beginning work, and have a fire-safe workspace to handle fuel and lubricants. By assembling the proper PPE, tools, and specialized equipment, technicians can conduct efficient, precise, and safe service on the STIHL 028AV SUPER while minimizing downtime and enhancing overall reliability.
Initial inspection and trouble diagnosis
Before attempting any maintenance on the STIHL 028AV SUPER, perform a thorough pre-service inspection to establish a baseline condition and identify potential safety hazards. Begin by ensuring the unit is completely powered down, cooled, and disconnected from any ignition source or fuel supply. Visually inspect the exterior for cracks, loose fasteners, or damaged components that could affect operation. Check the air filter housing, fuel tank, and recoil starter for signs of wear or deformation, and verify that hoses and clamps are secure and intact. Document any observed anomalies with notes and photos to guide the diagnostic process and prevent overlooking subtle issues during disassembly.
Move to a careful pre-check of the fuel system, as improper mixtures or contaminated fuel are common causes of starting and running problems. Inspect the fuel cap venting, fuel lines, filter, and carburetor inlet for leaks or blockages. If the unit has been stored with fuel for an extended period, anticipate varnish deposits and degraded fuel that can impede fuel flow. Ensure the carburetor diaphragm is not swollen or torn, and confirm that the primer bulb, if present, operates smoothly without cracking. A clean, dry, and well-ventilated work area helps prevent introducing contaminants during inspection and reassembly.
Next, evaluate the ignition system and compression indicators to determine whether the engine synchronization and timing are within factory specifications. Remove the spark plug and examine its electrode gap, insulator cleanliness, and evidence of fouling or damage. A spark test with a proper tester can verify ignition spark strength; a weak or intermittent spark often points to coil or wiring issues. Additionally, perform a quick compression check if possible, noting whether readings fall within the manufacturer's expected range for the 028AV SUPER. Abnormal compression often signals worn piston rings, cylinder wear, or valve leakage that requires more extensive repair work.
With the unit in a safe, stable position, perform a functional inspection of the drive and clutch mechanisms, including the chain brake, sprocket, and bar oil system if equipped. Ensure that the drive mechanism engages and disengages smoothly without unusual resistance or noise. For chainsaws like the 028AV SUPER, check the chain pitch, bar wear, and lubrication channels to confirm proper operation. Look for oil leaks or seepage around seals and gaskets, which can indicate degraded seals or improper resealing after service. A systematic physical assessment helps isolate problems that are electrical, mechanical, or related to fuel delivery, guiding subsequent diagnostic steps.
Pre service checklist
Initiate the pre service checklist as a baseline control to minimize the risk of misdiagnosis. Verify model and serial information to confirm correct parts compatibility and service specifications. Gather all necessary tooling, a clean work surface, and appropriate safety gear before beginning disassembly. Confirm that replacement seals, gaskets, and consumables match STIHL’s recommended parts list for the 028AV SUPER. Record initial observations, including smells, unusual sounds, and any suspected fuel or oil contamination. A disciplined checklist ensures that critical safety and performance parameters are not overlooked during the inspection and contributes to a faster, more reliable repair workflow.
Common issues and symptom mapping
Develop a symptom-to-cause mapping to streamline troubleshooting and reduce unnecessary disassembly. Common starting problems may trace to stale fuel, clogged carburetor jets, or air leaks in the intake boot. Poor acceleration or stalling at idle often points to a dirty carburetor or a faulty diaphragm, while smoking or rich running can indicate incorrect idle mixture or a leaky fuel line. Difficulty in starting after long storage frequently correlates with spark plug fouling or degraded ignition components. If the unit runs intermittently or loses power under load, assess the fuel supply system, air filtration integrity, and possible exhaust restrictions. A well-documented mapping reduces guesswork and speeds efficient repairs by guiding technicians to the most probable root causes first.
Diagnostic procedures and flow
Follow a structured diagnostic flow to ensure comprehensive assessment without duplication of effort. Start with safety checks and quick functional tests to identify immediate hazards. Proceed to air and fuel path inspection, including air filter condition, carburetor cleanliness, and fuel quality, then verify ignition performance through spark testing and compression checks. If initial tests are inconclusive, isolate subsystems through controlled isolation techniques, such as temporarily sealing intake paths or swapping known-good components where feasible. Throughout the process, document all measurements, adjustments, and outcomes to build a traceable service record. This methodical approach improves diagnostic accuracy, minimizes repair time, and helps preserve the long-term reliability of the STIHL 028AV SUPER engine.
Disassembly and parts identification
Before initiating any disassembly of the STIHL 028AV SUPER, ensure the engine is cool and the saw is secured on a stable work surface. Disconnect the spark plug boot and ground the spark plug to prevent accidental ignition of any residual fuel. Use a clean, labeled workspace and have a magnetic tray ready to organize fasteners and small components. Review the machine’s model number and match it with the service manual to confirm correct torque specifications and component layouts. Take clear photographs at key steps to aid reassembly and minimize the chance of misplacing any parts. Wear appropriate personal protective equipment, including cut-resistant gloves and eye protection, to reduce the risk of injury during disassembly.
When removing covers and guards, detach the fuel line and ensure there is no vapor pressure or fuel leakage. Work methodically from the exterior toward the interior, keeping track of which screws correspond to which covers, as some fasteners may be of different lengths. Keep track of any clips, springs, or detents that secure covers, and replace any bent or damaged fasteners during reassembly. Inspect the exterior cooling fins and intake areas for debris and clean as needed before removing internal components. Label each cover with a small marker or tape to preserve the original orientation, which helps maintain correct alignment and fitment on reassembly. After all screws are removed, gently pry the cover away using appropriate tools to avoid bending sheet metal or damaging internal gaskets.
Component identification and labeling begins with a systematic mapping of all major assemblies: carburetor, ignition module, crankshaft, piston and ring, cylinder, muffler, and air filter housing. As you expose each assembly, photograph or draw a simple schematic showing how each part interfaces with adjacent components. Verify the presence of model-specific markings, part numbers, and alignment notches to ensure accurate identification. When labeling parts, note any progressive wear indicators, such as scored piston skirts, scratched crank journals, or clogged passages, so you can evaluate whether replacement is necessary. Use a clean, lint-free cloth to wipe surfaces and verify fitment tolerances as components are set aside for inspection. Maintain an orderly workflow so that return-to-service checks can be performed quickly and safely during reassembly.
Air system and intake maintenance
The air system on the STIHL 028AV SUPER is critical to achieving consistent fuel metering and optimal engine performance. Begin with a thorough inspection of all accessible air pathways, including the air filter housing, intake boot, and carburetor side of the air path. Remove any debris or accumulated dust with a clean, dry brush or compressed air held at a safe distance to avoid damaging delicate parts. While inspecting, check for signs of wear, cracks, or deteriorated seals that could allow unmetered air to leak into the intake, which would undermine mixture control and cause erratic engine behavior.
During routine maintenance, the air filter should be inspected for clogging or oil saturation and replaced or cleaned according to service guidelines. When filtering elements are visibly dirty or saturated, replace them with OEM-compatible parts to maintain proper airflow resistance and filtration efficiency. After replacing, reassemble the housing ensuring all seals seat evenly and the filter is oriented correctly to prevent unfiltered air from bypassing the filtration path. A properly sealed system helps sustain peak engine performance and prolongs the life of the carburetor and ignition timing components.
Carburetor air adjustments require precise tuning to accommodate changes in altitude, temperature, and fuel quality. Start with the manufacturer’s recommended baseline settings and only adjust after confirming the engine runs reliably at idle and under light load. Use a tachometer or known-good test methods to verify that the idle speed and high-speed mixture achieve clean combustion without signs of rough idle, hesitation, or black smoke. Any adjustment should be performed in small increments with careful observation of engine response, ensuring that the air bleed passages and idle circuits remain unobstructed by debris or varnish buildup.
Inspect the intake manifold and boot for signs of cracking, deformation, or hardening that could cause air leaks. Gaskets and o-rings should be checked for integrity and replaced if compressed or damaged. When removing and reinstalling components, apply a light coating of the appropriate sealant or gasket compound as specified by the service data, and torque fasteners to the recommended specification to avoid leaks. After servicing, perform a leak-down or smoke test if available to confirm a sealed intake system, which helps prevent lean-running conditions and improves overall starting, throttle response, and fuel economy.
Regular maintenance of the air system not only improves performance but also extends the life of the engine and related components. Periodically remove the carburetor and inspect the intake boots for deteriorated rubbers or loose clamps, replacing any suspect parts promptly. Keep the air paths free of sawdust and resin buildup by cleaning with approved solvent and ensuring the air filter remains effective. Maintaining a clean, sealed intake system ensures consistent mixture delivery, reliable starts, and long-term reliability of the STIHL 028AV SUPER.
Air filter inspection and replacement: The air filter should be visually inspected at each service interval for dust, oil saturation, or physical damage. A dirty or clogged filter restricts airflow and can cause the engine to run rich, leading to reduced power and increased fuel consumption. Replace filters with OEM equivalents when signs of wear appear, and clean reusable elements following the manufacturer’s cleaning procedure if applicable. After care, ensure the filter housing seals correctly to prevent unfiltered air from bypassing the filtration path, and verify that the air intake duct and fittings are free of cracks or obstructions.
Carburetor air adjustments: For optimal operation, verify that the carburetor’s air screws and adjustment needles are set to factory-recommended baseline values before making any changes. Adjustments should be performed in small increments while monitoring engine response, including idle stability, throttle transition, and acceleration. Do not force adjustments beyond the limits specified by the service data, as over-lean or over-rich mixtures can cause overheating, poor startup, and potential damage to the exhaust and catalyst areas. Document all changes and recheck timing if the model requires it after air adjustments.
Intake manifold and boot checks: Inspect the intake manifold and boots for signs of leaks, cracks, or softened rubber that could alter mixture and performance. Replace any compromised components and reseal with appropriate gaskets and clamps. After installation, perform a leak check with a safe method approved for small two-stroke engines, ensuring there are no vacuum leaks around the intake. Regular inspection of these components is essential for maintaining consistent power delivery, smooth idling, and reliable cold starts across operating conditions.
Cooling and exhaust system service
The cooling system is essential to maintaining optimal operating temperatures for the STIHL 028AV SUPER during extended use. Begin with a thorough inspection of the cooling fins around the cylinder and flywheel housing, looking for bent or blocked fins, debris buildup, and signs of corrosion. Use a soft brush or compressed air to remove dust and particles, taking care not to force debris deeper into crevices. Verify that the cooling passages remain clear by inspecting any cooling shrouds or guards for damage or deformation that could impede airflow. It is important to ensure that the air intake areas remain unobstructed by leaves, grass, or residual oil leaks, as restricted airflow can lead to overheating and accelerated component wear.
Regular maintenance of the cooling system helps prevent premature engine wear and ensures consistent performance. After cleaning, inspect the intake screen and replace it if damaged or excessively clogged. When reassembling, confirm that the engine cooling shroud sits securely against the cylinder and that mounting studs are free of cracks. Periodically check for signs of coolant leakage or oil spraying near the cooling surfaces, which may indicate seals or gaskets requiring replacement. The operator should establish a routine where the saw is wiped down after use and allowed to cool before inspecting cooling components, reducing the chance of thermal shock during maintenance.
Spark arrestor and muffler maintenance plays a critical role in both performance and safety. Remove the muffler and visually inspect the spark arrestor screen for glazing, holes, or excessive buildup of carbon. A clogged screen restricts evacuation of exhaust gases and increases back pressure, which can reduce engine efficiency and create hot spots in the exhaust path. If glazing is present, carefully clean the screen with a solvent and a soft brush, ensuring no fibers are left unattached. When reinstalling the muffler, confirm that all fasteners are torqued to the manufacturer's specifications and that gaskets are intact, as a loose connection can cause exhaust leaks and abnormal noise during operation.
Additionally, examine the exterior of the muffler for signs of cracking or warping, which may indicate impact damage or thermal fatigue. Damaged mufflers should be replaced promptly to maintain proper exhaust flow and to reduce the risk of fire from accumulated flammable materials near hot surfaces. It is advisable to perform a function check after maintenance by starting the saw in a well-ventilated area and listening for abnormal exhaust tones or rattling, which could signal loose components. Regularly cleaning and inspecting the spark arrestor ensures reliable engine starts and steady idle performance, contributing to safer and more efficient operation in varied work conditions.
Exhaust leak checks are a critical safety and performance measure. Visually inspect the entire exhaust system for cracks, loose joints, or worn gaskets that could allow exhaust gases to escape into the operator’s environment or back into the engine. Use an appropriate leak-detection method, such as a soapy water test around joints and gaskets while the engine is running, to identify elusive leaks. If a leak is detected, tighten connections according to the torque specifications and replace any damaged gaskets or sections of the exhaust pipe. After completing repairs, re-check all fasteners for proper torque and ensure that there are no exhaust leaks that could impair engine performance or create hazardous fumes for the operator. Routine leak checks should be integrated into regular maintenance intervals to sustain efficiency, comply with safety standards, and extend the life of the exhaust system components.
Lubrication and drive train maintenance is essential for reliable performance and extended life of the STIHL 028AV SUPER. Regular lubrication reduces wear, minimizes friction, and helps keep the chain drive running smoothly under load. Begin by inspecting all lubrication points to confirm there is no leakage or blockage, and ensure that the oil reservoir is clean and filled to the recommended level. Use only the manufacturer-approved oil type and viscosity, and verify that the oil lines and fittings are secure before operation. Establish a consistent maintenance routine that coincides with running hours or calendar intervals, whichever is appropriate for your typical usage, and document each service for traceability.
Lubrication points and intervals should include the bar and chain oil system, as well as any drive shaft or bearing housings that require periodic oiling. For the bar and chain, check the oiler nozzle for obstruction and adjust the flow according to the engine temperature and cutting conditions. Inspect oil lines for cracks or leaks, and replace any damaged hoses promptly. A common practice is to lubricate while the saw is running at low speed to observe a steady oil spray from the bar tip. Record the oil interval in the service log and align it with chain tension checks to maintain consistent performance.
Chain drive and sprockets inspection is a core part of preventive maintenance. Remove the bar and chain following the manufacturer’s safe procedures, then inspect the drive sprocket for hooked or chipped teeth, wear on the chain drive boss, and any play in the clutch assembly. Check the drive shaft seal for oil seepage, which can indicate bearing wear or a failing seal. Measure chain stretch with a ruler or calipers; if the chain exceeds the manufacturer’s specified limit, replace it to prevent high-speed kickback and excessive wear on the bar. Reassemble the bar and chain with the correct torque on all fasteners, and verify that the chain moves freely with proper tension before starting the engine again. Document all findings and actions taken to ensure future reference during subsequent maintenance cycles.
Bar and chain maintenance is critical for clean cuts and tool longevity. Regularly inspect the bar rails for uneven wear, burrs, or cracks, and file or replace as needed to maintain parallelism with the chain drive. Check the chain for sharpness, proper depth gauges, and uniform tension; hone or replace cutters as required, ensuring that the drive links are seated correctly in the bar groove. Remove any sawdust and debris from the bar groove, oil ports, and chain catcher area to prevent heat buildup and binding. Reinstall the bar and chain following the sequence specified by STIHL, re-tension to the correct specification, and re-check the overall performance under light load before resuming work. Maintain a documented schedule of bar and chain inspections to support consistent, safe operation.
Electrical system diagnostics require a systematic approach to identify faults without causing additional damage to the machine. Begin with a visual inspection of the wiring harness for signs of abrasion, heat damage, or pinched conductors. Carefully check the routing of all wires to ensure they are seated properly in loom channels and that protective sleeves remain intact. Look for corroded connectors, loose terminals, or melted insulation, which can create intermittent faults or complete circuit opens. Use a clean, well-lit workspace and handle wiring with care to avoid introducing new faults during inspection. Document any irregularities and prepare a clear plan for targeted testing based on observed conditions.
A thorough sensor and switch test begins with obtaining the correct service manuals and wiring diagrams for the STIHL 028AV SUPER. Disconnect power and use a digital multimeter to verify supply voltages at each sensor and switch while the engine is in a safe state. Check for continuity across sensor circuits and ensure that signal reference grounds are solid, as a floating or high-impedance ground can yield inaccurate readings. When testing switches, verify that activation and deactivation occur with consistent, repeatable resistance changes and that no external force is causing false triggers. If a sensor or switch reads outside the specified range, replace it or service the associated harness to restore reliable operation. Keep records of measured values to support future maintenance decisions and troubleshooting efforts.
Troubleshooting electrical faults involves narrowing down the location of the fault through a process of elimination. Start by isolating suspected sections of the wiring harness using compatible test leads and jumpers to simulate signals while monitoring system responses. Inspect fusible links and circuit breakers to confirm they are functioning within their rated specifications and that no protects have appeared tripped due to transient overloads. Analyze the engine control module or ignition module procedures for diagnostics codes if applicable, and cross-reference these codes with the fault symptom history. Pay particular attention to grounds and power supply integrity, as intermittent voltage drops can masquerade as sensor or actuator faults. Conclude with a verification run that confirms normal operation under typical load conditions and document any anomalies observed during the test run for future reference.
The STIHL 028AV SUPER chainsaw employs a coordinated throttle and choke system designed to optimize starting performance and engine stability across operating conditions. The throttle linkage actuates the carburetor to regulate fuel metering, while the choke assembly constricts air flow to enrich the fuel mixture during startup. Proper inspection of the throttle and choke components includes verifying that the throttle trigger returns to idle smoothly, the choke plate operates unobstructed, and any idle speed adjustment screws function without binding. When the engine is cold, engaging the choke should visibly restrict air intake and promote easier starts, while disengaging the choke once a stable idle is established prevents excessive fuel consumption and fouling. Regular maintenance should include cleaning any carbon buildup on the carburetor and ensuring that cables or springs exhibit the correct tension to avoid unintended throttle engagement or post-start hesitation.
Safety interlocks are a critical line of defense for operator protection and equipment longevity. The trigger interlock must prevent the throttle from being engaged when the hand guard or bar cover is in an unsafe position, and the chain brake should activate in response to abrupt lever movement or inertial shocks. A routine safety check involves confirming that the on/off switch remains clearly labeled and functions as a decisive power control, that the chain brake engages promptly when tested with the front hand guard, and that the start/stop mechanisms reset reliably after engine starts. Inspect interlock wiring and connections for signs of wear, corrosion, or loose terminals, then replace any compromised components following the manufacturer's torque specifications. It is essential to validate that engine-stop positions correspond to safe shutdowns and that the chain catcher and anti-kickback features are intact and properly aligned.
Control feedback and indicators play a significant role in diagnosing operation and ensuring a consistent user experience. The ignition system should present a reliable spark aura with consistent compression, while the carburetor adjustments ought to reflect stable engine behavior across throttle ranges. Dashboard indicators, if present, should illuminate during startup and then settle into a steady state without flickering, signaling normal function. Operators must verify that the choke, throttle, and stop controls actuate with tactile feedback, returning to their intended resting positions without sticking. When performing diagnostics, observe the engine's response to throttle input and note any abnormal idle, misfire, or hesitation, which may indicate misadjusted fuel ratios, air leaks, or degraded seals. Document all observed indicators and corrective actions, then implement preventive maintenance to preserve accurate feedback and reliable control throughout the service life of the STIHL 028AV SUPER.
Calibration and performance tuning for the STIHL 028AV SUPER requires careful attention to idle speed, mixture settings, bar length compatibility, and precise chain tension. Begin by establishing a clean baseline: ensure the spark plug is in good condition, the air filter is unobstructed, and the carburetor is accessible for adjustments. Use the manufacturer’s recommended idle speed range as a target, and verify that the engine maintains steady idle stability without unwanted surging or stalling. When adjusting the mixture, make small, incremental changes, allowing the engine to respond between iterations. A rich mix can lead to carbon buildup and poor idle, while a lean mix may cause overheating and aggressive throttle response. Document the initial settings and test each adjustment under light, medium, and full throttle to observe consistency across operating conditions.
Bar length and chain tension verification is critical for safe, efficient operation. Confirm the installed bar matches the manufacturer’s specification for the 028AV SUPER, ensuring correct gauge, drive sprocket size, and chain pitch. Inspect bar wear, groove condition, and oiling passages, replacing components as needed to prevent uneven chain wear. For tension, set the chain just snug enough to raise it slightly from the bar nose without sagging. Rotate the chain by hand to verify smooth movement and absence of binding. Recheck tension after a brief operation, as heat can cause the chain to extend slightly; re-tension if necessary to maintain optimal performance and reduce kickback risk.
Final performance checks involve validating the overall saw operation under load and at various speeds. Start with a smooth idle, then progressively apply throttle to reach mid-range RPM, observing for any misfires, hesitations, or unusual noises. Perform a controlled cut on a test log of standard dimensions to assess cutting efficiency, chain speed, and exhaust characteristics. Monitor exhaust temperature and spark plug color as indicators of combustion quality; exceptionally dark or sooty plugs suggest a rich condition, while a very light plug may indicate a lean condition. If any abnormal readings are detected, revert to baseline settings, re-verify carburetor adjustments, and confirm that fuel quality and filter condition are not contributing factors. Complete a final safety check of all shields, spark arrestor, and throttle linkage to ensure reliable, repeatable performance in field conditions.
Seasonal maintenance plan is essential to keep the STIHL 028AV SUPER running reliably across varying conditions. At the start of each season, perform a thorough inspection of the chain brake, clutch drum, and drive sprocket to identify wear and ensure smooth operation. Replace or service air filtration components as needed to maintain optimal air flow and combustion efficiency. Establish a routine for inspecting fuel lines, seals, and gaskets to prevent leaks, and replace any aging parts to avoid performance degradation. Schedule carburetor adjustments after a period of use or following a fuel system service to ensure the engine maintains proper idle, lean/rich mixture, and power delivery. Finally, verify the exhaust system for any signs of scoring, carbon buildup, or leaks and clean or replace parts to maintain safe emission and noise levels.
Record keeping and parts inventory are foundational to efficient maintenance and rapid repairs. Maintain a detailed log of service dates, parts replaced, and engine performance observations to anticipate future maintenance needs. Keep an up-to-date inventory of critical consumables such as filters, gaskets, spark plugs, spark plug leads, fuel and oil lines, and seals, so that replacements are readily available. Document serial numbers, barcodes, and any warranties on major components to simplify future ordering and service recalls. Use the log to track run hours if available or approximate usage to estimate when components reach the end of their expected service life. Regularly review inventory levels and reorder items before stock runs low to minimize downtime.
Tips to extend service life for the STIHL 028AV SUPER focus on proactive care and correct operating practices. Use fresh, clean fuel mixed to the manufacturer’s specification and avoid ethanol-rich blends that can lead to varnish buildup and degraded performance. Maintain proper lubrication of moving parts by ensuring the bar oil reservoir and supply system function without leaks, especially under heavy cutting or continuous operation. Keep the cooling air path clear of debris to prevent overheating, particularly after long cutting sessions, and clean the cooling fins and air intake regularly. Practice gentle starting procedures and avoid sudden throttle changes to reduce wear on the carburetor and exhaust components. Periodically inspect and tighten all fasteners, especially around the bar and chain assembly, to prevent vibration-induced damage. Following these practices will help extend overall service life and reduce the frequency of major repairs.
Repairs and replacement parts management
Effective repairs begin with a clear assessment of the chainsaw’s condition, identifying both obvious wear items and hidden faults that can impact performance. Begin by inspecting the bar nuts, clutch assembly, and air filter for signs of uneven wear, scoring, or contamination. Document all findings with notes and photos to support warranty claims or service history. When evaluating fuel system components, check the carburetor diaphragms, fuel lines, and primer for stiffness, cracks, or leaks, and verify proper fuel mixture and oil-to-gas ratios. Establish a standardized approach to testing after maintenance, including idle stability, throttle response, and engine temperature behavior, to confirm that all repairs are functioning within spec before returning the tool to service.
Common wear items and replacements include the air filter element, fuel filter, spark plug, and bar/chain wear components. The air filter should be cleaned or replaced to maintain optimal airflow and engine performance, while the spark plug must exhibit correct gap and insulation integrity for reliable starts. The chain gauge and drive sprocket should be measured for wear, with replacement intervals based on runtime and usage conditions. Additionally, seals and gaskets around the crankcase or carburetor can deteriorate over time and may require replacement to prevent air or fuel leaks. Maintain a ready stock of these items and organize them by model compatibility to streamline the repair workflow and minimize downtime.
Where to source genuine parts requires careful verification of part numbers and supplier credibility. Prefer authorized STIHL distributors or certified dealers to ensure original equipment quality and compatibility. Cross-check parts through the official STIHL parts catalog, ensuring that updated numbers reflect any revisions or service updates. When ordering, request OEM certification or batch traceability documentation where available, and maintain a log of part lot numbers for warranty and recalls. For tools that have been discontinued or superseded, consult manufacturer support for permissible alternates or refurbished components that meet safety and performance standards. Keeping a relationship with trusted suppliers can reduce lead times and protect the integrity of repairs, especially for critical components like seals, carburetor diaphragms, and timing-related parts.
Reassembly and testing procedures should follow a disciplined sequence to avoid missed steps and ensure consistent results. Start by reinstalling the crankcase seals, gaskets, and orings, then carefully torque fasteners to the manufacturer’s specifications to prevent leaks or distortion. Reconnect fuel lines, the air intake system, and the carburetor with attention to proper routing and clamp security. After assembly, perform a controlled fuel test in a leak-free environment, verify compression, and confirm that the chain brake engages correctly. Conduct a functional test under load with a safe guide bar and chain installed, monitoring for smooth acceleration, consistent idle, and absence of abnormal vibrations or smoke. Finally, document the service details, including parts used, torque values, and test outcomes, to create a reliable service history for future maintenance and audits.
Troubleshooting quick reference
When diagnosing the STIHL 028AV SUPER, begin with a careful inspection of both the air and fuel systems, as these are the most common sources of performance issues. A thorough visual check on the carburetor, fuel lines, and filter can reveal restrictions or leaks that degrade engine efficiency. Verify that the compression feels adequate by a steady pull on the starter rope, noting any inconsistent resistance or unusual sounds that might indicate internal wear. In many cases, ignition problems are traced to a fouled spark plug or weak ignition coil, so remove, inspect, and replace components as needed to restore reliable sparking. If fuel delivery appears compromised, examine the fuel tank venting and the carburetor’s internal passages for varnish or debris, and consider a controlled rebuild using manufacturer-approved parts.
Symptoms to likely causes: If the engine starts with difficulty or idles irregularly, suspect fuel delivery issues, such as a clogged filter, restricted carburetor jets, or a defective needle valve. A noticeable loss of power during cutting or high-speed operation often points to intake leaks, bad gasket seals, or a worn carburetor diaphragm. Excessive exhaust smoke, particularly blue or black, can indicate oil intrusion or rich/lean fuel mixture imbalances that require carburetor adjustment or piston ring inspection. If the tool stalls immediately after throttle application, inspect the choke mechanism for sticking or improper operation, as this can cause inconsistent fuel metering. A steady noticeable vibration or abnormal noise may signal bearing wear, loose fasteners, or a misaligned bar and chain assembly that warrants a careful mechanical check.
Step by step corrective actions: Begin with a safety shutdown and disconnect the spark plug cap to prevent accidental starts. Drain and replace old fuel, then inspect and replace the fuel filter and primer bulb if present, ensuring airtight seals. Remove the carburetor for a thorough cleaning, paying close attention to the idle and high-speed jets; reinstall with the correct gaskets and diaphragms, and perform a precise adjustment according to the manufacturer’s torque and screw settings. Check the air filter for cleanliness and replace if fouled, ensuring the air intake path is clear. Inspect the ignition system by testing spark output under a dry, safe condition and replace the spark plug if it shows wear or fouling; verify proper spark plug gap. Reassemble with all fasteners torqued to specification and conduct a careful test run, observing for smooth idle, stable throttle response, and consistent power delivery.
When to seek professional service: If basic troubleshooting does not restore reliable operation, or if there are signs of internal engine damage such as scoring, seized components, or persistent loss of compression, professional service is advised. An authorized STIHL service technician can perform a comprehensive compression test, cylinder inspection, and precise carburetor overhaul using calibrated tools and genuine parts. If ignition faults persist after plug and coil testing, a trained technician should verify the wiring harness, kill switch integrity, and safety interlock compatibility to prevent unsafe operation. For units experiencing repeated fuel leaks or gasket failures, a certified technician can re-seat components with correct torque specifications and replace worn seals to ensure long-term reliability. Finally, if the bar and chain assembly exhibit excessive play or misalignment that cannot be corrected with standard adjustments, professional resurfacing or replacement may be required to maintain safe cutting performance.
Wiring diagrams for the STIHL 028AV SUPER provide critical insight into the electrical and ignition systems that power the unit. When approaching any repair, verify that the harness connections are intact, routed away from heat sources, and free of chafing or corrosion. Start by identifying the main power feed, kill switch circuit, ignition coil, and spark plug lead paths, ensuring continuity with a reliable multimeter. Cross-reference the diagrams with real-world harness layouts to confirm connector pinouts and signal routes before disconnecting any components, to prevent miswiring during reassembly. Pay attention to subtle color-coding and inline fuses, and document any deviations from the factory diagram for future maintenance records. Always work with the engine cool and the fuel system isolated to avoid accidental ignition or fuel leaks during inspection. A thorough understanding of schematics also aids in diagnosing intermittent electrical faults. When encountering erratic starting or no-spark conditions, trace the ignition circuit from the magneto to the spark plug, checking for loose grounds, damaged insulation, or damaged trigger wires. Examine the stator and flywheel timing marks as indicated in the schematics to confirm proper ignition timing, and use the diagrams to locate any unused or test points that may reveal a fault. If a relay or switch in the control circuit appears worn, use the schematic as a reference to test continuity and replacement requirements, ensuring that any replacements match the original specifications. Maintain clean, dry connectors and use dielectric grease to prevent future moisture-related corrosion, following the wiring diagram guidance for proper seating and locking of each plug. Finally, keep a copy of the wiring diagrams in the maintenance folder for quick reference during field service. Torque specifications
Accurate torque values are essential for secure fastener performance and long-term reliability of the STIHL 028AV SUPER. Begin with a clean engagement surface, removing any old lubricant or corrosion that might skew the measurement. Use a calibrated torque wrench set to the manufacturer’s specified range for each fastener size, and apply steady, even torque without jerking the tool to avoid over-tightening. When reassembling the carburetor mount, clutch components, or fuel system bolts, adhere strictly to the sequence outlined in the service data to prevent warping or gasket distortion, which can lead to leaks or misalignment. After completing the torque sequence, perform a final check by rechecking critical fasteners that are known to experience vibration and thermal cycling under operation. Document the torque values used and the date of service to facilitate future maintenance planning and traceability. Erratic performance can often be traced to improperly torqued fasteners in critical load-bearing areas. For example, ensure cylinder head bolts are torqued to the exact specification in a crisscross pattern to promote uniform clamping force and correct head gasket seating. Similarly, examine the crankcase fasteners, intake manifold bolts, and exhaust system hardware for uniform tightness and correct sequence. When replacing any gasket or seal, verify that mating surfaces are clean and free of scratches, as an improper seal can mimic a torque-related leak. Always torque to the spec while the engine is at or near operating temperature if the service data calls for this condition, and use thread-locking compounds only when specified by the guidelines. Recording torque values and any deviations creates a valuable reference for future service and helps maintain consistent engine performance. Service bulletin highlights
Service bulletins offer timely guidance on known issues, design changes, and recommended procedures for the STIHL 028AV SUPER. Review bulletins for updates on ignition timing adjustments, carburetor calibration, or cooling system modifications that may affect performance or reliability. Embrace any revisions that address recurring faults such as abnormal idle, richness or lean misfires, or unusual noise from the powerhead, since these updates often reflect the accumulated experience of field technicians. For each bulletin, compare the recommended steps with your current repair objective, documenting any conditions that match the bulletin’s criteria and applying the proven fixes accordingly. Maintain a log of bulletin numbers, dates, and outcomes of implemented updates to build a robust service history that informs proactive maintenance decisions. Finally, consider subscribing to bulletin notifications or maintaining an internal watch list to ensure the workshop promptly incorporates critical safety and reliability improvements as they are published.
Glossary and terminology
In this section, we clarify the common terms, acronyms, and measurement references you will encounter when servicing the STIHL 028AV SUPER chainsaw. A solid understanding of terminology helps ensure accurate diagnosis, proper maintenance, and safe operation. Familiarize yourself with these definitions to streamline troubleshooting and repair procedures. Accurate terminology also aids communication with suppliers, technicians, and service manuals to prevent misinterpretation of parts or procedures.
Key terms and acronyms commonly used in service manuals include CP (cold start position), RBI (rich/lean fuel adjustment guidelines), and CCW (cutter chain wear) among others. CP refers to the initial setting or position used when starting the engine under cool conditions, which can influence ignition timing and choke usage. RBI encompasses the recommended adjustments to air-fuel mixture to optimize performance across operating temperatures. CCW describes the measurable wear on the cutter chain, which is essential for determining replacement intervals and cutting efficiency. Understanding these terms helps technicians interpret diagnostic notes and calibration instructions accurately.
Measurement and unit references cover torque values, bore and stroke dimensions, and calibration tolerances that are critical for preserving engine performance and safety. Torque specifications are provided in Newton-meters (N·m) or foot-pounds (ft-lb) and must be applied with appropriate tool heads to avoid overtightening or under-tightening fasteners. Bore and stroke measurements define the engine’s internal dimensions and are used to assess wear or manufacturing variances during overhauls. Temperature and compression readings are often given in degrees Celsius and pounds per square inch (psi) respectively, ensuring consistency with standard STIHL maintenance data. Adhering to these units guarantees clear communication and improves the reliability of repair work conducted on the 028AV SUPER model.
Other commonly referenced terms include fuel system nomenclature such as metering, diaphragm, and carburetor idle speed. The metering system controls the amount of fuel that mixes with air, while the diaphragm regulates pressure differences that drive fuel delivery. Proper idle speed ensures stable operation at low throttle and prevents stalling during transitions. When diagnosing performance issues, precise interpretation of these terms helps identify whether an adjustment or replacement is required. A clear grasp of these concepts is essential for maintaining safe and efficient chainsaw operation and aligns with the manual’s repair procedures and recommended maintenance intervals.
Auxiliary terminology often appears in service notes to describe procedure steps or safety considerations, including lock-out/tag-out, start assist, and fuel stabilization practices. Lock-out/tag-out procedures prevent accidental engine start during disassembly or when components are exposed, protecting technicians from injury. Start assist refers to recommended techniques for safe ignition during priming or choke use, particularly after maintenance tasks that may affect initial fire-up. Fuel stabilization practices address fuel degradation risks when the saw sits unused, guiding players toward proper storage and periodic starting checks. Proficiency with these terms supports orderly work processes and reinforces safety throughout all service activities.