Knowledge Base
Preventive maintenance record guidance, commercial-equipment inspection information, and how Blue Collar Parts supports service records. Open content, licensed CC BY 4.0, available as Markdown and JSON.
Regulations
What 49 CFR Part 396 requires of carriers, inspectors, and equipment.
What is a Commercial Vehicle Inspection?
Annual, roadside, driver-report and PM checks are all called commercial vehicle inspections. Who does each and what record it leaves, under 49 CFR Part 396.
49 CFR Part 396 Explained, Section by Section
49 CFR Part 396 covers inspection, repair and maintenance of commercial motor vehicles: 396.1 to 396.25, including 396.9 roadside inspections, and Appendix A.
Annual DOT Inspection Requirements (49 CFR 396.17)
What the federal annual inspection actually requires — the 12-month rule, what counts as documentation on the vehicle, who may perform it, and which vehicles are exempt.
DOT Inspector Qualifications (396.19)
There is no single federal DOT inspector certification. Who may do the annual inspection under 49 CFR 396.19, and the separate 396.25 brake rule.
DOT Appendix A Checklist: Pass/Fail Standards
Appendix A to 49 CFR Part 396 sets the minimum standards for the DOT annual inspection: 15 categories, with measured limits for brakes, tires, steering and more.
DOT Inspection Sticker Requirements: What the Annual Decal Must Show (49 CFR 396.17(c))
The four elements federal law requires on an annual inspection sticker, why the address on it may not be the inspector's, and how the decal differs from an out-of-service sticker.
DOT Inspection Recordkeeping: How Long to Keep Annual Inspection Reports (FAQ)
Keep an annual DOT inspection report for 14 months, where the vehicle is housed or maintained. What the report must contain, who must produce it on demand, and what happens when the service provider that did the inspection is gone.
DOT Annual Inspection Report Form: What 49 CFR 396.21 Requires
Annual inspection report form: 49 CFR 396.21 prescribes no layout. It lists six things the report must contain, who keeps it, for how long, and who produces it.
Common DOT Inspection Requirements
Frequently asked questions about federal DOT inspection requirements for commercial vehicles under 49 CFR Part 396.
49 CFR 396.7 and 396.9: Unsafe Operation, Failed Inspections, and Out-of-Service Orders
Three different things that get confused: operating an unsafe vehicle under 49 CFR 396.7, failing an annual inspection, and being placed out of service at the roadside under 396.9. What each one means and what it obligates you to do.
Trailer ABS Light: What It Means When It Stays On
A trailer ABS light is the lamp that signals a fault in the trailer's antilock brakes. See what keeps it lit and what 49 CFR 393.55 requires of the trailer.
Slack Adjuster Adjustment: 49 CFR 393.47
A slack adjuster links an air brake chamber's pushrod to the camshaft and sets pushrod travel. Manual vs. automatic, and the 49 CFR 393.47(e) stroke limit.
Brake Chamber Air Leak and Replacement: Chambers, Hoses and Fittings
A brake chamber air leak can come from the chamber, its hose or its fittings. See where leaks show up, what brake chamber replacement involves, and what 49 CFR 393.45 and 396.3(a)(1) say.
FMCSA Out-of-Service Checks: What Inspectors Cite on Tractors and Trailers Put Out of Service
FMCSA out-of-service checks by equipment type: four checks (tires, brakes, air hoses, air leaks) covered 67.8% of tractors put out of service, and five covered 75.5% of trailers.
Lighting Violations by Truck Age: What FMCSA Roadside Inspections Cite
Lighting violations by truck age: 44.7% of cited tractors aged 15 or more had a lighting violation, against 13.5% of cited tractors aged 0-2. Tire violations are highest on the newest.
Maintenance
Practical preventive-maintenance guidance. Not an inspection standard.
What Is a PMI (Preventive Maintenance Inspection)?
A PMI, or PM inspection, is a scheduled check of a truck, generator or vessel. It records the equipment's condition, the work done and the next steps.
PM Inspection vs. DOT Annual Inspection
PM is scheduled maintenance for the customer; a DOT annual inspection is a separate federal requirement. A PM result is not a DOT inspection.
What Belongs in a PM Report for the Customer?
A useful preventive-maintenance report answers four questions: what was checked, what was found, what was done, and what comes next. Use this structure to make service work clear to the customer.
Complaint, Cause, Correction: The 3 C's
Complaint, cause, correction: what was reported, what was found, and the repair actually performed and verified. What goes in each line, with an example.
Semi Truck PM Checklist: What to Check by System
A semi truck PM checklist and inspection sheet: what to look at on each system, from engine oil to brakes, tires, lights and the fifth wheel, and a free PM form.
Diesel Generator Maintenance Checklist and Log: What a PM Covers
Diesel generator PM checklist and log: the seven areas a PM covers, why a maintenance log matters, and a free form to fill out on your phone.
Marine Diesel Engine Maintenance Checklist: What a PM Covers
Marine diesel PM checklist: the seven systems a PM visit covers, what your customer should receive, and a free form to fill out on your phone.
Diesel Mechanic Certifications Explained: ASE T-Series, the T8 PMI Test, and DOT Inspector Qualifications
What the common diesel technician credentials are: the ASE Medium-Heavy Truck tests (T1 to T8), the T8 Preventive Maintenance Inspection test, Master status, and how they relate to the federal DOT inspector qualification.
Diesel Engine Cooling System Maintenance: What a PM Covers for Trucks, Generators, and Marine Engines
What the cooling system does on a diesel truck, generator, and marine engine, why it gets its own section in a PM, how raw-water cooling differs, and what the customer's record should show.
Diesel Fuel System Maintenance: Filters, Water Separators, and Day Tanks
Why the fuel system gets its own section in a diesel PM, why water is the enemy on trucks, generators, and boats, how a generator day tank changes the picture, and what the customer's record should show.
Engine Oil, Transmission, and Hydraulic Fluids: The Fluid Side of a Diesel PM
Why oil and fluids anchor every diesel PM on trucks, generators, and marine engines: engine oil and filters, transmission, driveline, and marine gear fluid, and hydraulic systems, and what the customer's record should show.
Diesel Air Intake and Exhaust Maintenance: What a PM Covers
Why air intake and exhaust get their own place in a diesel PM on trucks, generators, and marine engines, how a marine exhaust elbow differs, and what the customer's record should show.
Battery, Charging, and Controls: The Electrical Side of a Diesel PM
Why batteries, charging, and controls get their own section in a PM for diesel trucks and generators, why a standby generator's start circuit matters most, and what the customer's record should show.
Marine Engine Corrosion and Zinc Anodes: Why They Get Their Own Place in a PM
Why sacrificial anodes and corrosion get a dedicated section in a marine diesel PM, how saltwater and raw-water cooling drive the wear, and what the customer's or operator's record should show.
Diesel Generator Load Bank Testing and Exercise Records: Why the Log Matters
What generator exercising and load bank testing are for, why a standby diesel generator needs a record of both, and what the customer's generator log should show after each PM.
Diesel Engine PM for Heavy Trucks
What a heavy-truck engine PM covers: the oil change, what an oil analysis report tells you, and where the service interval actually comes from.
Cummins X15 Oil Capacity
Cummins X15 oil change capacity is 36.3 to 43.8 liters (9.6 to 11.6 gal), per Cummins' quick reference guide, with its oil drain and overhead intervals.
Detroit DD13 and DD15 Oil Capacity and Valve Lash
Detroit gives a 40 qt (38 L) service fill (oil and filter change) for the DD13 and 45 qt (43 L) for the DD15 Gen 5, plus the DD15 valve lash interval.
Cummins B6.7 Oil Capacity
Cummins B6.7 oil capacity is 16.7 L (17.6 qt) total with the standard pan and 19.7 L (20.8 qt) with the high-capacity pan, per Cummins' quick reference guide.
Mack MP8 and Volvo D13 Oil Capacity
Mack gives the MP8 oil capacity as 44 qt (42 L) and Volvo the D13 as 33 qt (31 L). The oil change volume is a separate figure set by the pan and filter count.
PACCAR MX-13 Oil Capacity
PACCAR's EPA 2024 MX-13 spec sheet gives the oil system capacity as 42 U.S. quarts. Other emissions years have their own documentation.
Detroit Series 60 Valve Adjustment: Intake and Exhaust Lash
Detroit's Series 60 timing bulletin lists 0.203 mm (0.008 in.) intake lash on every model, and 0.508 mm (0.020 in.) or 0.660 mm (0.026 in.) exhaust lash by model and year. Source, and how to find your engine's setting.
DPF Cleaning and Regeneration: How a Diesel Particulate Filter Is Maintained
How a diesel particulate filter is cleaned: the filter comes off the equipment for ash removal or exchange. Also covers where the DPF fits with EGR, DOC and SCR.
DPF Cleaning vs. Regeneration: Which One Does the Filter Need?
Regeneration burns soot off a DPF in place; cleaning removes leftover ash and means removing the filter. Passive, active and parked regeneration explained.
Recording a DPF Service: What Belongs in the Record
What to record for a DPF service: the complaint, cause and correction, the diagnostic tool's readings, the cleaning method, and what the customer's copy shows.
DEF and SCR Basics: What They Do and What a Technician Watches
SCR converts NOx from diesel exhaust into nitrogen and water using DEF. What DEF contamination and crystallization look like, and what to record.
EGR Cooler Failure: What the Cooler Does and What to Record
An EGR cooler lowers recirculated exhaust temperature before it reaches the intake. General failure signs, how they overlap with other faults, and what to record.
Air Brake System: How Semi Truck and Trailer Air Brakes Work
How air brakes work on a semi truck and trailer, the parts of the system, and which air brake parts roadside inspectors cite most in FMCSA data.
Air Over Hydraulic Brakes: How They Work and Differ From Air Brakes
How air over hydraulic brakes work, how they differ from full air brakes and from car-style hydraulic brakes, and how the CDL rules treat them.
Semi Truck Brake Inspection: What a Brake Inspection Covers
A semi truck brake inspection looks at the whole air brake system, from air supply to wheel end. See what is checked, and how it differs from the federal annual inspection.
Semi Trailer Maintenance: The Trailer's Systems
A semi trailer has its own systems to maintain, separate from the tractor: brakes and ABS, wheel ends, tires, suspension, landing gear, and lighting.
Trailer ABS Troubleshooting: Power, Sensors and the Module
Trailer ABS troubleshooting checks the system in order: power to the module, the wheel speed sensors, the modulator, and the fault codes it reports.
Trailer Brake Adjustment: The Trailer's Side of the Air Brake System
Trailer brake adjustment starts on the trailer's own supply and service lines, its relay-emergency valve and spring brakes, not just the slack adjuster.
Trailer Wheel End Maintenance: Hub Oil, Grease and Bearings
Trailer wheel end maintenance covers hub oil or grease, hub seal replacement, and wheel bearing adjustment, and the difference between the two.
Trailer Air Ride Suspension: Air Springs, Height Control and Alignment
Trailer air ride suspension maintenance covers the air springs, height control valve, shocks, bushings and pivots, plus axle alignment at a category level.
Trailer Landing Gear Repair and Service
Trailer landing gear repair covers the crank and gearbox, the legs and pads, and the lubrication points that keep a trailer level when it's uncoupled.
Semi Trailer Lighting and Wiring: Trailer Light Repair and the 7-Way
Semi trailer lighting and wiring runs from the 7-way connector through the harness to every marker, clearance, turn and brake light. See where repairs start.
Semi Truck and Trailer Tires: What a Tire Inspection Covers
Semi truck and trailer tires as one system of tires, wheels, valve stems, inflation and wheel ends, and what a commercial truck tire inspection covers.
Semi Truck Tire Pressure and Trailer Tire Inflation Systems
Where the right semi truck tire pressure comes from, why it is checked cold, and how a trailer automatic tire inflation system adds air to a tire.
Truck Tire Tread Depth and Condition: Steer, Drive and Trailer
How truck tire tread depth is measured by position, where steer tire tread depth rules live, and the irregular wear and sidewall damage worth recording.
Wheel Seal Leaking? Steer and Drive Axle Hub Seal Replacement
What a leaking wheel seal looks like on a truck's steer and drive axles, what hub oil seal replacement involves, and what the record should show.
Recording a Tire and Wheel Service: What Belongs in the Record
What to record for a tire and wheel service: complaint, cause and correction, tire position, DOT code, pressures and tread depths as measured, and parts.
Running the business
Practical guidance for technicians who run a service business: customers, pricing, and the work behind the record. Not legal, tax, or insurance advice.
How to Become a Diesel Mechanic: Training, Certification, and Specialties (Generators, Marine, Heavy Truck)
The paths into diesel technician work: training programs, starting on the job, ASE certification, and specialties like generator service and marine diesel, plus what it takes to go out on your own later.
How to Start a Mobile Diesel Mechanic Business: The Decisions That Come First
Starting a mobile diesel or heavy equipment service business: what to decide about the work you take, the customers you serve, the truck and tools, registration and insurance, pricing, and the records your customers will judge you by.
How to Price PM Service and Set Mobile Mechanic Rates
How to build mobile mechanic and PM service rates from what your time actually costs: billable hours, travel, trip charges, parts and fluids, flat-rate versus hourly, and how to show the customer what they paid for.
How to Win Fleet Maintenance Contracts as a Mobile Service Provider
What fleet managers look for when they hand PM work to a service provider, what a fleet maintenance agreement usually defines, and how a mobile technician earns the account and keeps it.
Platform
What the Blue Collar Parts platform does, and where it stops.
What Blue Collar Parts Is
Blue Collar Parts turns each PM service and annual inspection into a record your customer can open: what was found, what was fixed, and who did the work.
Blue Collar Parts User Guide: From First Customer to Sent Service Record
The Blue Collar Parts user guide in order: set up your account, add customers and equipment, start the work, record the PM or inspection, and send the record your customer opens. Each step links to its full how-to.
Getting Started with Blue Collar Parts: Create an Account and Set Up Your First Customer
How to create a Blue Collar Parts account, confirm your email, and use the four-step setup to add your first customer and asset and see what your customer's record will look like.
How to Add Customers and Equipment (Assets) in Blue Collar Parts, Including VIN Decode
How to add a customer and the trucks, trailers, generators, and marine engines you service in Blue Collar Parts: required fields, why the customer's email matters, USDOT numbers, and decoding a VIN.
Look Up a Carrier's FMCSA Roadside Record by USDOT Number
How to see a motor carrier customer's public FMCSA roadside inspection record in Blue Collar Parts: save the USDOT number, read inspections, recorded violations and out-of-service violations, and fill the customer's details from the FMCSA census. Only the technician sees it.
How to Start a Service Event in Blue Collar Parts
How to start a preventive maintenance service event in Blue Collar Parts: choose the customer and asset, pick the type of work, and open the work.
How to Record a Preventive Maintenance Service in Blue Collar Parts
How the PM form works in Blue Collar Parts for trucks, generators, and marine diesel engines: answering items, readings and notes, reviewing each system, and filing the service record.
How to Record an Annual Inspection in Blue Collar Parts
How to record a federal annual inspection on a truck or trailer in Blue Collar Parts, what the qualification record is for, and what the record does and does not establish.
How to Send a Service Record to Your Customer in Blue Collar Parts
How to mark work complete, set the next service date, and send the record to your customer in Blue Collar Parts, what it costs and when you pay, and how to resend or change who receives it.
What Your Customer Receives: The Blue Collar Parts Service Record
What happens on your customer's side when you send a record from Blue Collar Parts: the email, confirming the record, how long the link works, and what the service record shows, including the record number.
How to Read a Blue Collar Parts Service Record: What the Colors and Marks Mean
What the green, red, amber and gray marks on a Blue Collar Parts service record mean, for an annual inspection and for a PM: the result at the top, the mark beside each point, and why every mark also has a shape and words.
Work, Sent, and Records: Tracking Jobs, the Dashboard, and the Calendar in Blue Collar Parts
How to find your jobs in Blue Collar Parts: the Work, Sent, and Records lists, the dashboard tiles, the calendar of next service dates, adding visits to Google Calendar, and looking up a record.
Digital Preventive Maintenance Service Records You Send to Your Customer
Learn how a preventive-maintenance service event becomes a record your customer receives: what was checked, what was found, what was done, and what needs attention next. Finishing the work and sending the record are separate steps.
Where Blue Collar Parts Fits Against 49 CFR Part 396
An obligation-by-obligation map of 49 CFR Part 396 and the limits of Blue Collar Parts annual-inspection and maintenance records. A digital record can support organization; it cannot establish compliance.
Using This Knowledge Base with LLMs and Agents
Every page here is available as clean Markdown and JSON, indexed by llms.txt, licensed CC BY 4.0, and versioned in a public Git repository. How to ingest it and how to cite it.