For immediate troubleshooting, begin by locating the air filter housing–a cylindrical black unit on the right side of the engine. Remove the single retaining bolt and inspect the filter for debris. If replacement is needed, use OEM part #568492-03 or equivalent with a minimum airflow rating of 12 CFM to prevent engine strain.
To access the carburetor assembly, disconnect the spark plug wire first, then detach the fuel line clamp (marked “B” in service manuals). Note the orientation of the primary fuel jet (#68491-01)–incorrect installation will cause hard starting or surging. Apply dielectric grease to the replacement jet’s threads to prevent corrosion.
When servicing the alternator stator, use a multimeter set to 200Ω to test winding resistance. Readings between 0.2Ω–0.5Ω confirm integrity; values outside this range indicate burnout. Replace with component #55166-75, ensuring the flywheel’s magnets align with the stator’s notched mounting posts (±3° tolerance).
The recoil starter requires reconstitution every 100 operating hours. Disassemble by releasing the three spring-loaded clips–do not stretch the recoil spring beyond its coiled state. Lubricate the bearing surface with silicone spray before reassembly to reduce drag on pull-start engagement.
For electrical continuity checks, reference wiring harness connector #78943-02. Probe pins 3 (black) and 6 (red) while idling; voltage should stabilize at 12.8V±0.3V. Deviations suggest a faulty voltage regulator (#86724-11), which must be replaced in-kind to avoid battery overcharging.
Breaking Down the D55168 Compressor: Critical Components and Maintenance Tips
Begin by locating the exploded view schematic for the portable air system–specifically, identify the piston assembly (item 12) and reed valves (items 24–26) before attempting any repairs. These components fail most frequently due to oil contamination or improper lubrication. Replace both piston rings (item 11) and valves simultaneously if wear exceeds 0.2mm or scoring is visible under magnification. Store replacements in a humidity-controlled environment below 50% RH to prevent premature degradation.
Pressure Switch and Motor Circuit Troubleshooting
Inspect the unloader valve (item 42) if the unit cycles abnormally–clogs here mimic pressure switch failure. Test switch continuity with a multimeter at the following intervals: 90 PSI (make), 120 PSI (break). Readings outside 0.3–0.7 ohms indicate replacement necessity. For the motor relay (item 33), check for discoloration on the coil terminals–blackening requires immediate capacitor (item 37) inspection. Capacitors should measure within ±10% of their rated μF; deviations trigger overheating.
- Air filter (item 5): Clean every 50 hours using compressed air directed at 45° to avoid embedment. Replace if pleats show tears.
- Belt tension (item 61): Adjust deformation to 0.3 inches at midpoint. Misalignment accelerates bearing wear (item 7).
- Drain valve (item 58): Activate weekly to expel condensate. Silence during opening signals clogging–soak in acetone for 30 minutes if corrosion is present.
When disassembling the pump head, arrange fasteners by size in a magnetic tray–the M8 bolts (item 4) securing the cylinder require 22 ft-lbs torque. Apply thread locker to the upper two bolts only; the lower pair must remain removable for future service access. Gasket surfaces (item 15) demand a metal scraper–avoid wire brushes, which create micro-grooves and future leaks.
- Use PTFE tape on the oil dipstick (item 29) threads to prevent false low readings.
- Inspect the thermal overload (item 36) for tripping frequency–replacement criteria: 3 trips/100 hours.
- Check wheel bearings (item 64) for axial play. Tolerance: 0.002 inches. Lubricate with NLGI-2 grease annually.
Locating the Manufacturer’s Schematic and User Guide for the D55168 Model
The most reliable source for the genuine breakdown chart and reference documentation is the official brand portal. Visit DeWalt Support and enter “D55168” into the search tool. Filter results by selecting “Diagrams” or “Manuals” to isolate the exact files. Download speeds are optimized for quick retrieval–expect the exploded view PDF to load in under 30 seconds on standard broadband connections.
Alternative Sources with Verified Schematics
| Platform | File Type | Notes |
|---|---|---|
| eReplacementParts | Interactive breakdown | Labelled sections with SKUs, updated quarterly |
| ManualsLib | PDF manual | Text-searchable, includes torque specs |
| Amazon product listing | Thumbnail previews | Low resolution; repeat sections omitted |
Third-party vendors like ToolPartsDirect archive snapshots synchronized with the manufacturer’s latest revisions. Prefer ZIP downloads containing both the schematic and troubleshooting workflows–separate files often split assemblies across pages, requiring manual cross-referencing. Bookmark the direct URL after locating the chart to bypass repeated searches.
Step-by-Step Guide to Locating and Requesting Components Using a Schematic
Begin by retrieving the official exploded view for the portable compressor model. This document lists every individual element with numerical identifiers–cross-reference each digit next to the faulty component with the legend at the bottom-right corner to confirm exact nomenclature. For example, item 17 typically corresponds to the pressure switch, while 22 indicates the air filter housing.
Verify the component’s condition against the visual reference. Rotate seals, gaskets, or hoses gradually between finger and thumb to detect micro-cracks invisible under direct light. Use a flashlight angled at 45 degrees to reveal hairline fractures in cast aluminum casings. Record measurements–inner diameter, thread pitch (e.g., 1/4″ NPT), and length–of any tubular or threaded elements before sourcing replacements.
Access the manufacturer’s authorized portal or approved distributor network. Input the numerical code from the schematic directly into the search field to avoid mislabeled alternatives. If the section displays a QTY column, note whether multiples are required–for instance, O-rings often need identical pairs, whereas screws may require six per assembly.
Matching Substitutes Without Manufacturer Data
When exact part numbers are unavailable, rely on dimensional comparisons. A digital caliper measures external diameters, while a depth gauge records groove widths for seals. Cross-check these values with industrial standards–ISO 3601-1 tolerances for O-rings, SAE J518 for hydraulic fittings. Always prioritize materials compatible with compressed air: Buna-N for gaskets up to 250°F, stainless steel for high-vibration mounts.
Consult third-party retailers specializing in pneumatic systems. Upload compressed image files (≤2MB in JPEG) of damaged components alongside measurements, specifying thread direction (left-hand vs. right-hand) and sealing type (flare, compression, or flat-face). Request a sample when bulk ordering gaskets, as slight dimensional variations may disrupt airflow calibration.
Inspect packaging for laser-etched identifiers before accepting delivery. Confirm that plastic clamshells include anti-static protection, especially for solenoid coils. For sheet-metal guards, verify powder-coat thickness with a micrometer (minimum 80 microns) to prevent premature corrosion.
Verification and Pre-Installation Testing
After receipt, conduct a dry-fit assembly without power. Spin threaded shafts manually to detect binding; compressed springs should rebound immediately without hysteresis. For diaphragms, stretch the component evenly across a clean flat surface–deformations indicate material fatigue. Replace any element failing tactile inspection regardless of visual integrity.
Store uninstalled components in moisture-resistant bags with silica desiccant packets. Seal bags immediately after opening to prevent lubricant degradation on moving assemblies. Label each sealed unit with installation torque values–typically 30-40 in-lbs for housing screws, 60-70 in-lbs for base mounts–to avoid over-tightening during final assembly.
Step-by-Step Breakdown of Major Components in the Exploded View
Begin disassembly by securing the motor housing–locate the retaining bolts at positions 12A and 12B on the schematic. These fasteners, typically M8 x 1.25 threading, require a 13mm socket. Apply penetrating oil if corrosion is present; torquing should not exceed 25 Nm to avoid stripping. Note the orientation of the brush holder assembly (item 7)–misalignment during reassembly will cause premature wear on commutator contacts.
The armature (reference 15) demands careful handling. Inspect the laminations for discoloration or pitting before removal; overheating symptoms indicate replacement necessity. Use a gear puller for extraction if resistance exceeds 10 lbs of pull force–pry tools risk damaging the shaft’s precision-machined grooves. Verify bearing preload after installation by rotating the armature manually; smooth resistance without play confirms proper seating.
Examine the switch mechanism (component 4) for debris in the trigger contacts. Carbon buildup can be removed with 600-grit abrasive paper–avoid solvents that degrade plastic housings. Check the return spring tension; weak springs should be replaced with OEM-specified models (tolerance: ±0.2mm free length). Reattach the power lead (item 5) using crimp connectors soldered at 350°C for 3 seconds maximum to prevent insulation melt.
Finalize assembly by aligning the gear case (part 21) with the motor’s dowel pins. Grease the helical gears using NLGI Grade 2 lithium complex–overpacking leads to heat retention. Tighten case screws in a cross pattern to 15 Nm, then verify gear mesh by rotating the output shaft; audible grinding or visible play indicates misalignment, requiring partial disassembly to correct.