Kei Truck Maintenance: The Schedule, the Timing Belt and What to Do First

A Kei Truck is easy to keep running once it is caught up. The catch is that most arrive with no service history you can trust and with rubber and fluids of unknown age. This page gives a schedule built from common guidance for 1990-2001 trucks, the jobs to do first, and what changes from engine to engine. Where the factory service manual for your chassis says something different, follow the manual.

What should you service first on a newly bought Kei Truck?

Assume nothing has been done: in the first week, replace the timing belt and water pump unless you hold a dated receipt, then renew every fluid, filter and spark plug. Japanese service records rarely travel with an exported truck, and a belt of unknown age is the most expensive gamble on the truck. Work through these steps before long drives or heavy loads.

1. Find the chassis and engine codes

   Read the ID plate and note the chassis code, such as DD51T or HA4, and the engine code. Order every part by these codes, not by model year.

2. Replace the timing belt and water pump

   Unless you hold a dated receipt, replace the belt, tensioner and water pump together, plus the camshaft and crankshaft seals if they show oil.

3. Change the engine oil and filter

   Drain the oil, fit a new filter and drain plug washer, and refill with the grade and viscosity your manual lists for your climate.

4. Refresh the cooling system

   Drain and refill the coolant, and replace soft or cracked hoses, the radiator cap and the thermostat if their age is unknown.

5. Change the gear oils

   Replace the oil in the transmission, in the transfer case on 4WD trucks, and in the differentials.

6. Flush the brake fluid and inspect the brakes

   Flush the old fluid with the grade on the reservoir cap, then check the pads, rear shoes, hoses and parking brake.

7. Renew filters and ignition parts

   Fit new air and fuel filters and spark plugs. On distributor engines, replace a worn cap, rotor and plug wires too.

8. Check the battery, belts and tires

   Test the battery and charging output, inspect the drive belts, and replace tires that are cracked or too old to trust.

Almost all of it is hand-tool work. Order parts by the chassis code on the ID plate (for example DD51T, HA4 or S110P) rather than by model year, because one model name covers several generations with different parts. If you are still shopping, the Kei Truck buying guide covers what to inspect before money changes hands.

What is the Kei Truck maintenance schedule?

The intervals below are common guidance for 1990-2001 Kei Trucks, in miles and kilometers, and the manual for your engine takes priority. Use the short end of each range for what manuals call severe service: short trips, dust, long idling, heavy loads and farm work. That describes most Kei Truck lives.

Tires deserve a closer look. On US-market tires, the Department of Transportation (DOT) code ends in a four-digit date, two digits for the week and two for the year, so 2219 means the 22nd week of 2019 (49 CFR 574.5). Tires that arrive on an imported truck often carry no DOT code at all. Many vehicle makers advise replacing tires about six years after manufacture, and tire makers commonly treat ten years as the limit.

When should you change a Kei Truck timing belt?

Common Japanese guidance is every 100,000 km (about 62,000 miles) or 10 years, whichever comes first, and right away on any truck without a dated receipt. Nearly every engine in the importable 1990-2001 trucks uses a rubber timing belt: Suzuki's F6A, Honda's E07A and E07Z, Daihatsu's EF series, Subaru's EN07 and Mitsubishi's 3G83. Suzuki's K6A, which replaced the F6A in later Carrys and is just reaching the 25-year line, uses a timing chain instead.

A broken belt stops the engine on the spot. On an interference engine, the pistons can also hit open valves and bend them, which turns a belt job into a cylinder head repair. Owners and parts sellers disagree about which Kei engines are interference designs, and we could not confirm any of them from a factory document. Plan as if a snapped belt will damage yours.

Do the whole job once:

• Replace the belt, the tensioner and any idler pulley together.
• Swap the water pump at the same time, since most of the labor overlaps.
• Replace the camshaft and crankshaft oil seals if they show any oil, because oil degrades a new belt.
• Refill with fresh coolant, since the system is partly drained anyway.

Timing belt kits group these parts by chassis code. Write the date and odometer reading on a tag and zip-tie it in the engine bay, so the next person working on the truck knows where it stands.

What should you know about each Kei Truck engine?

Five engine families power nearly every importable Kei Truck, and each has habits worth knowing before you pick up a wrench. Full output and dimension figures are on the Kei Truck specs page.

Whatever the engine, overheating is the failure that turns cheap ownership expensive. Keep chaff and mud out of the radiator fins, replace soft or swollen hoses, and watch the gauge when the truck works hard on a hot day. Radiator parts such as caps, hoses and thermostats cost little next to a warped cylinder head. Before you add lights or a winch, have the charging system tested, and replace tired alternators and belts first.

How do you care for a carbureted Kei Truck versus a fuel-injected one?

Check which one you have before ordering parts: many 1990s trucks are carbureted, and Suzuki's January 1999 Carry specification still listed a carbureted base engine beside fuel-injected versions. The engine code and the service manual will tell you.

Fuel matters for both. The Environmental Protection Agency (EPA) does not allow E15 gasoline in model year 2000 and older cars and light trucks, which covers most importable Kei Trucks. Use regular unleaded with no more than 10% ethanol, or ethanol-free fuel for a truck that sits for long periods.

For carbureted trucks:

• Add fuel stabilizer before any break longer than a few weeks.
• Check that the choke gives a fast idle when cold and releases fully once warm.
• Replace cracked rubber fuel and vacuum lines, which leak air and fuel with age.
• Rebuild a gummed-up carburetor with fresh gaskets, needle and seat rather than replacing it. Carburetor parts are listed by chassis.

For fuel-injected trucks:

• Keep the fuel filter on schedule, because injectors need clean fuel at steady pressure.
• If the idle wanders, clean the throttle body and idle-control passages and check the vacuum hoses before replacing sensors.
• Keep the battery terminals and ground straps clean and tight, since low voltage upsets electronic injection.

How do you keep a Kei Truck from rusting?

Rust is the one problem that can end a Kei Truck's working life, so rinse the underside after every drive on salted roads and inspect the frame at least twice a year. Look hardest at the frame rails, the cab corners and the floor under the mats, the rocker panels, the wheel arches, the bed floor and its seams, and the points where the bed bolts to the frame.

Prevention that works:

• Rinse the underbody all winter, including inside the frame rails where you can reach.
• Before winter, apply an oil- or wax-based rust inhibitor to the frame, seams and cavities. Hard rubberized coatings can trap water once they crack, so inspect them every year.
• Keep the drain holes in the doors, cab floor and bed clear.
• Lift the floor mats after wet days so the floor can dry.
• Touch up chips in the bed and cab paint before they spread.

Once a panel has rotted through, replacing it with a new exterior body part beats patching the same spot every year.

How should you store a Kei Truck for the off-season?

For storage longer than a month, stabilize the fuel, keep the battery charged, and protect the truck from moisture and rodents.

• Fill the tank with fresh fuel plus stabilizer, then run the engine long enough to draw the treated fuel through the lines.
• Connect a battery maintainer, or disconnect the negative cable. If the battery is old, a new battery costs less than a spring tow.
• Inflate the tires to the pressure on the tire label and move the truck a few feet every few weeks.
• Chock the wheels and leave the parking brake off, so the rear drum shoes cannot stick to the drums.
• Block the air intake and exhaust openings against mice, and leave a note on the steering wheel to remove the covers.
• Before the first drive, check every fluid and the brakes, and look inside the air filter box for nests.

Can you do Kei Truck maintenance yourself?

Yes: most jobs need only metric hand tools, a JIS screwdriver set, a jack with stands and the service manual for your chassis. Japanese Industrial Standard (JIS) cross-head screws look like Phillips screws, but a Phillips driver tends to cam out and strip them, while a JIS driver fits properly.

Expect tight access. The engine sits under the seats on most models, under the bed on the Acty and at the rear on the Sambar, so a first timing belt job takes patience. Plan a full weekend or hand that one job to a shop. Air conditioning is a special case for paid work: anyone who services vehicle air conditioning for payment must be certified under Section 609 of the Clean Air Act (EPA).

Keep a log of dates, odometer readings and parts. It keeps you on schedule and it helps when you sell. Once the truck is sorted, the Kei Truck mods guide covers sensible upgrades, and the off-road guide covers 4WD, tires and recovery.