The Truck Maintenance Checklist We Run Before Every Season

A checklist is only as good as what's on it — and the order you run it. Generic lists cover the basics. What they usually miss is the sequence a working mechanic actually uses, and the two items that look fine on a walk-around but only a measurement catches.

This is the walk I do and the schedule I'd hand a new owner-operator on the I-94 corridor.

The Pre-Trip Walk-Around, In Order

Federal regulation requires a driver vehicle inspection before and after every trip — 49 CFR § 396.11 sets that floor. What it doesn't set is the order that keeps you from missing something in a hurry.

Pre-trips are always overlooked. They're your first chance to catch something and fix it before you're on the road — because a failure out there costs exponentially more.

Start driver-front, go clockwise:

1. Under the hood. Oil level, coolant level, belts for wear or damage, anything wet or leaking. Get this before you touch a tire. If there's a fluid leak, you want to know while the engine's still cold, not after it's been running hot for a hundred miles.
2. Driver-side steer tire. Tread depth, sidewall for cuts or bulges, valve cap present, and gauge the pressure. A tire that looks full may not be. Use the gauge — every time, every tire.
3. Down the driver side. Steer and drive tires, rims, lug nut condition — anything loose or out of place. Check the fuel tank mounting and the water separator. Note anything wet under the truck.
4. Fifth wheel and gap. Look at the gap around the kingpin, check that the release handle is fully seated, look for excessive fore-aft slop in the coupling. A fifth wheel that isn't locked all the way is the one that drops a trailer in a yard.
5. Trailer walk. Lights, mud flaps, tires, brake chambers, slack adjusters, airbags. Glad hands and air lines for chafe and cracking — a chafed air line fails at the worst moment.
6. Across the back. Lights, trailer doors latched, plate lamp working.
7. Up the passenger side. Same as the driver side — tires, rims, lugs, fuel tank, any leaks. Don't rush the passenger side because you already did the other one. Same check, same discipline.
8. In the cab. Build air to governor cutout. Check the pressure-build time — slow build means a compressor problem or a leak somewhere. Verify the low-air warning triggers at the right pressure. Test service brakes and parking brake. Lights all around, wipers, horn.

That order is not arbitrary. Starting under the hood while the engine's cold, working clockwise so you don't cross your own path, and finishing in the cab after everything is built and ready — that's how you catch the thing you'd otherwise miss when you're tired and trying to get rolling.

Two Things Only a Measurement Catches

A walk-around catches what's visible. There are two items on every truck that can be completely out of spec and look normal from the outside.

Brake Pushrod Stroke

A brake chamber can look perfectly normal and already be past its legal limit. On a standard Type 30 chamber, that limit is 2 inches of stroke. You check it by building full air pressure, shutting the engine off, applying the service brakes hard, and measuring the exposed pushrod with a tape or a ruler. With the engine off, you can also hear service-side air leaks while the brakes are applied. There is nothing on the outside of a chamber that tells you the stroke is over the line. You only know with a measurement.

Pushrod stroke is the item most likely to turn a PM into a same-day repair when I'm in the bay. I'll go in to measure it and find a chamber already past spec. That becomes a fix-it-now — I'm not signing off a truck that's already over the limit and sending it down the road.

Tire Pressure

A tire can look full when you have multiple sets and the trailer is loaded or unloaded. That's not something you catch by eye, and a tire iron only tells you the tire is not flat. It does not tell you the pressure. Carry a gauge. Use it on every tire, every pre-trip.

The Shortcut That'll Cost You

The shortcut is the thump test — hitting a tire with a tire iron and calling it checked. Thumping is the most common pre-trip shortcut I see out here, and it's the one that gets drivers into real trouble — not because they're careless, but because a tire iron feels like a check when it isn't.

Use a tire pressure gauge so you know exactly what's in your tire. Taking a couple extra minutes to check and fill can save you thousands. That's why I tell every owner-operator: carry a gauge, use it every time.

The Service Schedule

For a new owner-operator who wants a plan they can actually run, here's how I lay it out:

Daily — pre-trip and post-trip walk-around per the sequence above. Gauge tires. Drain the water separator. Thirty seconds with a drain valve beats a set of injectors when water gets through.

Monthly — grease the fifth wheel.

Every 25,000 miles or quarterly, whichever comes first — this is the PM visit and the oil-change visit at the same time. The truck's already in the bay, so you do everything while you're there: oil and filter, fuel filters and separator, all fluids checked and topped, coolant tested for freeze point and additive level, full brake inspection with pushrod stroke and lining measured, slack adjusters, grease every zerk including the fifth wheel, tires gauged and tread measured, air system check (build time, dryer condition, tank drain), belts and hoses, battery and charging system, suspension and airbags, lights all around, and a scan-tool pull for stored and pending codes.

The brakes are the item most likely to produce a same-day repair out of that list. That's not a problem with the PM — that's the PM doing its job. Better a chamber out of spec in the bay than on a Level 1 inspection on the side of the road.

Around 300,000 miles — full coolant service and valve adjustment per the OEM schedule.

Annually — the DOT inspection, which runs on its own clock regardless of mileage or PM timing.

For the interval rationale behind each of these — why 25K on modern iron but shorter on older trucks, and how oil analysis settles the exact number for your route — see the full maintenance guide with interval rationale. That guide covers the reasoning. This checklist is the sequence.

Heading Into Winter

The standard PM schedule doesn't change in winter, but I add a seasonal check before the cold settles in. By the time temperatures drop, these items need to already be done:

• Drain tanks of any water. Moisture that's harmless in July freezes lines and valves in January.
• Service the air dryer. The dryer has to be working before the cold season, not after you've already lost air to ice.
• Treat fuel. If you're running #2, treat before filling so it mixes through the tank.
• Begin switching to #1 diesel. This matters especially in the northern U.S. and Canada, where winter fuel problems show up fast.

Summary

• Start driver-front, go clockwise: hood, driver-side tires, trailer walk, passenger side, cab. Same check, same order, every time.
• Brake pushrod stroke on a standard Type 30 chamber: 2-inch limit, measured at full air pressure with the engine off so you can also hear service-side leaks. It only shows up with a measurement.
• A tire can look full when the trailer is loaded or unloaded. Gauge every tire, every pre-trip.
• The thump test tells you a tire isn't flat. That's all. A gauge tells you the pressure.
• PM every 25,000 miles or quarterly — oil change, brakes, coolant, fifth wheel, everything done at once while the truck's in the bay.
• Fifth wheel greased monthly; full coolant service around 300,000 miles; DOT annual on its own clock.
• Before winter: drain tanks of water, service the air dryer, treat fuel, and begin switching to #1 diesel where winter calls for it.

Conclusion

The checklist works when you run it the same way every time, in the same order. The walk-around sequence keeps you from skipping a side in a hurry. The measurement items — brake stroke and tire pressure — are the ones that look fine on the outside right up until they're not.

If your service schedule has slipped, or you want a mechanic to run through this list with you before a long haul or a seasonal change, book a mobile PM visit and MTTR comes to your yard or lot. We work through the list, measure what needs measuring, and fix what we find — so you don't find it later on the shoulder of I-94. For diesel-specific interval guidance and the reasoning behind each service item, see diesel-specific maintenance.

Frequently Asked Questions

What order should I do a pre-trip walk-around?

Start driver-front, go clockwise. Under the hood first — oil, coolant level, belts, anything wet or leaking. Then front tires: tread, sidewall, valve caps, gauge them. Down the driver side: steer and drive tires, rims, lug condition, fuel tank and separator, fifth wheel and gap. Walk the trailer: lights, mud flaps, tires, brake chambers, slack adjusters, airbags, glad hands and air lines for chafe and leaks. Across the back: lights, doors, plate lamp. Up the passenger side, same as the driver side. Then in the cab: build air, check the low-air warning and pressure-build time, test service and parking brakes, lights, wipers, horn.

How do you check brake pushrod stroke on a pre-trip?

Build full air pressure, shut the engine off, apply the service brakes hard, and measure the exposed stroke on the pushrod. With the engine off, you can also hear service-side air leaks while the brakes are applied. On a standard Type 30 chamber the legal limit is 2 inches. A chamber can look perfectly normal on the outside and already be past that limit — you only know with a measurement.

Is thumping tires a reliable pre-trip check?

No. A tire iron tells you a tire isn't flat — it doesn't tell you it's low. A tire can look full when you have multiple sets and the trailer is loaded or unloaded. Use a tire pressure gauge so you know exactly what's in the tire. Taking a couple extra minutes to check and fill can save you thousands.

How often should a truck get a PM service?

Every 25,000 miles or quarterly, whichever comes first. That PM is the oil-change visit — the truck's already in the bay, so brakes, coolant, fifth wheel, and everything else gets done at the same time. Heading into winter, add a seasonal check: drain tanks of any water, service the air dryer, treat fuel, and begin switching to #1 diesel, especially in the northern U.S. and Canada.

By Andy Mandt — Owner, Mandt Truck & Trailer Repair (15+ yrs). This guide was drafted with AI assistance and reviewed by Andy before publication.