Used Fertilizer Tender Truck Inspection Checklist: What to Check Before You Buy

Buying used · 8 min read

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A used fertilizer tender truck earns its keep in short, intense bursts: loaded heavy, driven to the field, unloaded fast, and back for another load, all day, through the busiest weeks of the season. That cycle is hard on both halves of the machine — the truck underneath and the tender body on top. Fertilizer is corrosive, loads are heavy, and a tender that looks solid standing empty can show its problems only when it is loaded and running. Here is what to check before you buy.

Start with the tender body: compartments, gates, and corrosion

The tender body is where fertilizer lives, so it is where corrosion does its work. Open every compartment and look inside with a flashlight. Check the floors and walls for thinning, pitting, and holes, especially along the seams and in the corners where fertilizer sits and moisture collects. Press on any soft-looking spots; a floor that flexes under your hand has lost thickness.

Check the compartment gates and doors. Each one should open fully, close tight, and latch securely. A gate that sticks, binds, or will not seal clean means product leaking between compartments or metering unevenly — and on a tender, a leaking gate can contaminate one product with another.

Look at the lids and covers. They should close tight and seal against rain. A tender that takes on water in a storm delivers wet fertilizer, and wet fertilizer bridges, clogs, and corrodes from the inside out. Check the hinges, latches, and seals for daylight around a closed lid.

The delivery system: conveyor or auger

The conveyor or auger is the working heart of a tender, and it is where most used tenders show their age. Run it empty first, then loaded if the seller will allow it.

For a belt conveyor, watch the belt track: it should run centered without wandering to one edge or squealing against the frame. Check the belt for fraying edges, cracks, cuts, and missing lacing, and check every splice for fasteners that are pulling through or edges that lift. Look at the drive roller and idlers for fertilizer buildup packed hard against them, and check that the take-up still has travel left — a take-up run to the end of its adjustment means the belt has stretched about as far as it can.

For an auger, check the flighting for wear. Worn flighting is thinner and shorter, which changes how fast the auger moves product. Check the auger bearings for play, listen for grinding as it turns, and look at the tube or trough for wear-through spots where abrasive product has thinned the metal.

On either system, check the discharge spout. It should swing or adjust freely and lock in position, with no worn-through elbows where product changes direction. That is where abrasive fertilizer does its damage first.

Scales and the weigh system

A tender without an accurate scale is guessing at every load, so test the scale before you trust it. If the truck has a scale system, ask the seller to demonstrate it with a known weight or a partial load you can verify against a certified scale. Watch the reading as product is added and removed; it should move smoothly and return to the same empty weight each time.

Check the load cells and their mounts. Look for bent brackets, cracked welds, and wiring that has been pinched or patched. Load cell cables run through a corrosive environment, so check every connection for green corrosion and every cable run for chafing where it passes through the frame.

The truck underneath: chassis, engine, and drivetrain

A tender body in great shape on a worn-out truck is still a worn-out truck, so inspect the chassis like you would any used commercial truck. Check the frame rails for cracks, especially around the suspension mounts, the fifth-wheel or body mounting points, and anywhere the tender body bolts to the frame. Look for fresh paint over one section or plates bolted over a joint — both can hide a repair you want to know about.

Start the engine cold if you can. Watch for hard starting, excessive smoke, and warning lights that stay on. Let it reach operating temperature and listen for knocks, ticks, and exhaust leaks. Check the coolant, oil, and transmission fluid for level and condition; milky oil or coolant means water where it should not be.

Take it for a drive, loaded if possible. The transmission should shift cleanly through every gear without slipping, flaring, or harsh engagement. The clutch, if it has one, should engage smoothly without chatter or slipping under load. Listen for driveline vibration and rear-end noise, and note any pulling, wandering, or looseness in the steering.

Hydraulics and PTO

Most tenders run the conveyor or auger off hydraulics or a PTO, and both need a loaded check. Inspect every hydraulic hose for cracking, chafing, and weeping at the fittings. Fertilizer dust and sun are brutal on rubber, and a hose that weeps standing still can fail under pressure.

Cycle the hydraulics through their full range and watch for smooth operation with no jerking or stalling. Run the delivery system under load and listen: a hydraulic motor that whines, a pump that labors, or a PTO shaft with a torn guard all need attention, and a missing or damaged PTO guard is a safety issue, full stop.

Tires, brakes, and suspension

Tender trucks carry heavy loads on a seasonal schedule, which means tires often age out before they wear out. Check every tire for sidewall cracking, cuts, and uneven wear, and read the date codes — tires well past their service life are on borrowed time regardless of tread depth.

Test the brakes. Air brakes should build pressure promptly, hold it with the engine off, and release cleanly. Listen for air leaks at the chambers, valves, and lines, and check that the parking brake holds on a grade. If the truck has hydraulic brakes, check the pedal feel and look for fluid leaks at the wheels and master cylinder.

Walk the suspension: springs, air bags, bushings, and shocks. Look for broken leaves, cracked spring hangers, air bags that leak down overnight, and bushings that are worn through. A tender that sags to one side empty will only get worse loaded.

Electrical, lights, and safety gear

Tender trucks work early mornings, late nights, and on public roads, so the electrical system matters more than it looks. Power up the truck and work through every light: headlights, markers, turn signals, brake lights, and the work lights over the tender body and conveyor. Check the beacon or strobe if it has one.

Check the wiring harnesses, especially where they run along the frame and near the tender body. Fertilizer dust plus moisture turns connectors into green, crusty problems, and intermittent connections are the hardest faults to find later. Wiggle the connectors while the lights are on and watch for flickering.

The loaded test run

Do not buy a tender you have not seen work under load. If the seller can arrange it, watch a full cycle: load product, drive a short distance, and unload it. Watch the gate open cleanly, the conveyor or auger meter steadily, and the spout deliver without surging or spilling. Listen for bearing noise and belt slip that only show up under load.

Watch the scale through the whole cycle if the truck has one. A scale that reads steady empty, drifts loaded, and returns to a different empty number is telling you something is wrong. And watch the truck itself under load: does it sit level, brake straight, and steer true with a full tender body? A truck that only behaves empty is not the truck you will be driving in season.

Records to ask for

Ask for maintenance records on both halves of the machine: engine and transmission service, brake and suspension work, and tender-body work including belt or auger replacements, bearing work, gate repairs, and scale calibrations. Ask what products the tender carried, because a tender that ran fertilizer its whole life corrodes differently from one that ran seed or feed. Ask how it was stored and whether the body was washed down after fertilizer use — a tender washed after every season and stored under cover shows it in the body, the conveyor, and the frame.

Walk the body, run the delivery system loaded, test the scale, and drive the truck loaded before you buy. A tender that passes all four is a machine you can put to work the first week of the season.