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newSchoolWorks.com › VoTechWorks › Transportation › Small Engine & Power Equipment › Capstone Project: Small Engine & Power Equipment Overhaul and Documentation › Lesson 1
TRN-SMAL74-07 · Lesson 1 · 18 clock hours · lab

Project Planning, Equipment Selection, and Pre-Teardown Assessment

Objective. Given a faulted unit selected from the shop equipment pool, the student produces a signed safety plan, a completed customer intake work order, and a documented pre-teardown assessment that identifies all suspected fault systems before any disassembly begins.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a certified examiner or master technician in the trade or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Why Planning Before Teardown Matters

The single most common mistake a beginning technician makes is picking up a wrench before understanding what is wrong. A systematic pre-teardown assessment protects the customer's equipment, protects your time, and protects you. In a professional shop, no disassembly begins until a signed work order and a documented diagnostic exist. That standard applies here, too. Your capstone project mirrors real shop practice from the first minute.

Step 1 — Unit Selection and OEM Manual Retrieval

When you select or are assigned a faulted unit from the shop pool, write down the complete model number and serial number before you do anything else. These numbers are stamped or labeled on the engine and on the equipment frame; they are not always the same. The model and serial number unlock the correct OEM service manual, the correct parts diagram, and the correct specifications. Using data from a slightly different model year is a leading cause of incorrect clearances and wrong parts orders.

Locate the printed or digital OEM service manual for your exact unit. Manufacturers such as Briggs & Stratton, Stihl, and Honda publish technician service manuals that include specifications, torque values, diagnostic flowcharts, and wiring diagrams. These are your authoritative source — not a general video or a third-party guide.

Step 2 — Customer Intake Work Order

Treat every shop unit as if a paying customer brought it in. Complete the shop's customer intake form in full:

A complete work order is a legal and professional document. Incomplete fields are not acceptable in the field and are not acceptable here.

Step 3 — Pre-Teardown Diagnostic Assessment

The goal of the pre-teardown assessment is to identify every suspected fault system before one fastener is loosened. Work through the OEM diagnostic flowchart in order. Record every result on the standardized diagnostic worksheet — numbers, not impressions.

Compression test: Disable the ignition (spark plug wire off and grounded). Crank the engine through the compression gauge. Record the reading in psi. Compare to the OEM specification. Low compression points toward worn rings, a leaking head gasket, or valve problems.

Spark test: Use an inline spark tester between the plug wire and a known-good spark plug. Crank the engine and observe. Record whether spark is present, absent, or weak. Absence or weak spark points toward the ignition module, coil air gap, flywheel key, or kill-switch wiring.

Visual fuel system check: With the fuel valve off (or fuel line pinched), remove the air filter and inspect the carburetor inlet. Check the fuel filter for discoloration or debris. Smell the fuel for varnish (stale fuel). Record what you see. Do not apply flame or create ignition sources near fuel.

Electrical continuity checks: Using a digital multimeter set to continuity or resistance (Ω), check the kill-switch circuit and any charging circuit connections accessible without disassembly. Record readings.

Circle each suspected fault system on the worksheet: engine (compression/mechanical), fuel system, ignition system, charging system, or drive/transmission system. You must support every circled system with at least one measurement or observation.

Step 4 — Writing the Project Plan

Your one-page project plan must include:

1. Repair sequence — list the systems you will address in order, from most likely cause to least.

2. Special tools required — flywheel pullers, valve spring compressors, timing lights, tachometers. List them so you can confirm shop availability before teardown.

3. Estimated parts list with placeholder costs — use OEM parts diagrams and online pricing to estimate. Accuracy is expected; "unknown" is not acceptable for identifiable components.

4. Safety checklist — this is mandatory and must be complete before the instructor signs off.

Safety: Lockout/Tagout and PPE

Before any assessment or disassembly, apply lockout/tagout (LOTO) correctly. For small engine equipment this means:

Required PPE for this phase includes safety glasses at all times, nitrile gloves when handling fuel or oil, and hearing protection when running compression or spark tests with the engine cranking. Dispose of drained fuel and used oil in labeled, sealed containers placed in the designated waste collection area — never pour down a drain or on the ground.

Your safety checklist must name every LOTO point specific to your unit. A generic checklist is insufficient. The instructor will not sign the plan if LOTO points are missing.

Instructor Sign-Off

No disassembly is authorized until your instructor reviews and signs your diagnostic worksheet and project plan. All three elements must be satisfactory: complete and accurate fields, at least two suspected fault systems supported by measurement data, and a correct LOTO safety plan. This is not a formality — it is the professional standard that protects equipment, parts, and people.

Key terms10

Model number / serial numberAlphanumeric codes stamped or labeled on the engine and equipment frame that identify the exact product variant and production unit, used to retrieve the correct OEM service manual and parts diagrams.
Customer intake work orderA formal shop document that records reported symptoms, service history, visible condition, and unit identification before any diagnostic or repair work begins; it serves as both a professional and legal record.
Pre-teardown assessmentA structured diagnostic process performed with the unit fully assembled that uses tests and visual inspection to identify suspected fault systems before any disassembly occurs.
Compression testA measurement made with a compression gauge inserted in the spark plug hole to determine whether the engine's combustion chamber seals adequately; the result is compared to the OEM specification in psi.
Inline spark testerA diagnostic tool connected between the spark plug wire and a spark plug that provides a visible indication of whether the ignition system is producing a spark of adequate intensity.
Lockout/tagout (LOTO)A safety procedure that isolates a machine from all energy sources — including disconnecting the spark plug wire, isolating fuel, and disconnecting the battery — and applies a physical lock or tag so the machine cannot be energized accidentally during service.
Fault systemOne of the major subsystems of a power equipment unit — engine (compression/mechanical), fuel, ignition, charging, or drive — identified during diagnosis as a likely location of the defect.
OEM service manualThe official technical publication issued by the original equipment manufacturer that contains specifications, torque values, diagnostic flowcharts, wiring diagrams, and repair procedures for a specific model.
Diagnostic worksheetA standardized form on which the technician records every measurement and observation from the pre-teardown assessment, providing a written basis for the repair sequence and parts estimate.
Project planA one-page document prepared before teardown that lists the repair sequence, required special tools, estimated parts with costs, and a complete safety checklist including LOTO points and PPE requirements for each phase.

Worked examples4

1. A walk-behind mower is cranked through a compression gauge and reads 70 psi. The OEM service manual specification is 90 psi minimum. By what percentage is the reading below specification, and what fault system does this implicate?
  1. Identify the measured value: 70 psi.
  2. Identify the minimum specification: 90 psi.
  3. Calculate the shortfall: 90 − 70 = 20 psi.
  4. Calculate the percentage below specification: (20 ÷ 90) × 100 = 22.2%, rounded to 22%.
  5. A reading 22% below the minimum specification indicates inadequate combustion chamber sealing, which implicates the engine (compression/mechanical) fault system — possible causes include worn piston rings, a leaking head gasket, or a damaged valve seat.
Answer: The reading is 22% below the OEM minimum (20 psi short of 90 psi), which implicates the engine compression/mechanical fault system.
2. During an electrical continuity check, a student measures resistance across a kill-switch circuit using a digital multimeter. With the switch in the RUN position the meter reads 0.3 Ω. With the switch in the STOP position the meter reads 0.4 Ω. What is wrong with this result, and what fault system does it implicate?
  1. In the RUN position a kill switch should be open (infinite resistance / OL on the meter) because the circuit is not grounding the ignition module.
  2. In the STOP position the switch should be closed (near-zero resistance, typically under 1 Ω) to ground the module and stop the engine.
  3. The measured 0.3 Ω in the RUN position means the switch is not fully opening — the circuit has a partial or continuous ground path when it should be open.
  4. This means the ignition module may be partially grounded during operation, causing intermittent or weak spark.
  5. This implicates the ignition system fault system; specifically the kill-switch circuit.
Answer: The kill switch is not fully opening in the RUN position (should read OL/infinite resistance but reads 0.3 Ω), indicating a faulty or stuck switch that partially grounds the ignition — implicating the ignition system fault system.
3. A student's parts estimate lists a carburetor rebuild kit at $18.75, a spark plug at $4.50, a fuel filter at $3.25, and an air filter at $6.00. What is the total estimated parts cost, and what percentage of the total does the carburetor kit represent?
  1. Add all parts: $18.75 + $4.50 + $3.25 + $6.00 = $32.50 total.
  2. Calculate the carburetor kit percentage: ($18.75 ÷ $32.50) × 100 = 57.69%, rounded to 57.7%.
  3. Record both figures on the project plan parts list.
Answer: Total estimated parts cost is $32.50; the carburetor rebuild kit represents approximately 57.7% of that total.
4. A student sets up a compression test on a small chainsaw engine. The OEM specification is 130 psi. The first crank gives 95 psi, the second gives 110 psi, and the third gives 118 psi. Should the student record 118 psi or continue cranking, and why?
  1. Compression test procedure requires cranking the engine until the gauge reading stabilizes (stops rising between strokes).
  2. The readings are still rising: 95 → 110 → 118 psi; the reading has not stabilized.
  3. The student should continue cranking until two consecutive strokes produce the same or nearly the same reading.
  4. Recording the highest single reading before stabilization will give an artificially low result because the rings have not yet fully seated oil and the check valve in the gauge has not reached true peak pressure.
  5. Once the reading stabilizes, record that value and compare to the 130 psi specification.
Answer: The student should continue cranking until the reading stabilizes across two consecutive strokes before recording the final compression value; a still-rising reading is not the true peak.

The math in this lesson1

Learners compute compression 22% below a 90 psi minimum during pre-teardown assessment.
7.RP.3
Brush up in the math halls at newSchoolWorks.com:
In class: Students choose or are assigned a faulted unit (walk-behind mower, string trimmer, generator, chainsaw, or ATV) and retrieve its OEM service manual; they complete a customer intake form recording all reported symptoms, hours of service if known, and visible external condition, then photograph the unit from all four sides and record the model and serial number. · Working through the OEM diagnostic flowchart, students perform a systematic no-disassembly assessment — compression test, spark test, visual fuel system check, electrical continuity checks — recording every result on a standardized diagnostic worksheet and circling each suspected fault system (engine, fuel, ignition, charging, drive) before committing to a disassembly plan. · Each student writes a one-page project plan listing the repair sequence, all required special tools, estimated parts list with placeholder costs, and a safety checklist confirming lockout/tagout points, required PPE for each phase, and waste disposal method for fuel and oil; the instructor reviews and signs the plan before teardown is authorized.
Materials: Shop equipment pool (mowers, trimmers, generators, chainsaws, ATVs with documented faults), OEM service manuals, compression gauges, spark testers, digital multimeters, digital calipers, camera or phone for documentation, shop work order forms, diagnostic worksheets, PPE (safety glasses, nitrile gloves, hearing protection), lockout/tagout kit
Check: Instructor reviews the pre-teardown diagnostic worksheet and project plan; competence is confirmed when all required fields are complete and accurate, at least two suspected fault systems are identified with supporting measurement data, and the safety plan correctly identifies all lockout/tagout points — all three elements must be satisfactory before teardown is authorized (pass = instructor sign-off, no incomplete fields).

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Work order and documentation practices
1. Why must the model number and serial number be recorded before any other action is taken on a unit?
Engine diagnosis and troubleshooting
2. During a pre-teardown spark test on a walk-behind mower, the inline spark tester shows no spark. Which fault systems should be circled on the diagnostic worksheet at this point?
Engine diagnosis and troubleshooting
3. A student records a compression reading of 75 psi against an OEM minimum of 100 psi. What is the percentage by which the reading falls below the specification?
Safety — lockout/tagout and PPE
4. Which lockout/tagout step is most critical before performing a compression test on a gasoline-powered engine?
Safety — lockout/tagout and PPE
5. An instructor declines to sign a student's project plan. The diagnostic worksheet is complete and two fault systems are identified with measurements. What is the most likely reason the plan was not approved?
Engine diagnosis and troubleshooting
6. A student uses a digital multimeter to check a kill-switch circuit. With the switch in the RUN position, the meter reads 0.2 Ω instead of OL (open). What does this indicate?
Work order and documentation practices
7. Which document must be completed and signed by both the student and the instructor before any disassembly is authorized in this capstone project?
Engine diagnosis and troubleshooting
8. A student notices varnish-like discoloration and a stale odor in the carburetor bowl during the visual fuel system check. No other tests have been performed yet. Which fault system should be circled on the diagnostic worksheet, and what should the student do next?
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