The 2021 Daihatsu Hijet with the 0.66L KF three-cylinder is a workhorse kei truck, but that tiny turbocharged engine works HARD under load. Timing chain wear, valve train noise, and head gasket seepage are the real-world issues that catch owners off-guard, especially if the truck sees commercial use or repeated heavy loading.
Timing Chain Stretch and Guide Wear
Common · high severityTypical onset: 60,000-90,000 mi
Symptoms: Rattling on cold start that fades after 10-15 seconds, Check engine light with cam/crank correlation codes, Rough idle or hesitation during acceleration
Fix: Full timing chain kit with tensioner, guides, and gears. This is a 6-8 hour job due to tight engine bay access and need to remove multiple accessories. Critical to catch early before chain jumps timing.
Estimated cost: $1,200-2,000
Hydraulic Lifter Noise and Collapse
Common · medium severityTypical onset: 50,000-100,000 mi
Symptoms: Persistent ticking or tapping from valve cover, worse when cold, Loss of power on hills or under load, Noise doesn't improve with oil changes
Fix: Replace all lifters/tappets, inspect cam lobes for scoring. 4-5 hours labor with valve cover removal and careful reassembly. Oil starvation from aggressive driving or extended oil change intervals accelerates this.
Estimated cost: $800-1,400
Head Gasket Seepage and Failure
Occasional · high severityTypical onset: 70,000-120,000 mi
Symptoms: White smoke from exhaust on startup, Coolant loss with no visible leaks, Oil milkshake on dipstick or in coolant reservoir, Overheating under load
Fix: Head gasket replacement requires head removal, resurfacing, and pressure testing. 8-10 hours labor. The KF engine runs hot under boost, and repeated overheating cycles from heavy loads or climbing grades in hot weather weaken the gasket.
Estimated cost: $1,800-3,200
Transmission Oil Cooler Line Corrosion
Occasional · medium severitySymptoms: ATF leaking from lines near radiator, Transmission slipping or harsh shifts, Burnt smell from engine bay
Fix: Replace corroded hard lines and cooler if contaminated. 2-3 hours labor. Road salt and environmental exposure rot these lines faster than expected. Catch early before debris circulates through transmission.
Estimated cost: $400-800
Harmonic Balancer Separation
Rare · high severityTypical onset: 80,000-130,000 mi
Symptoms: Vibration at idle that worsens with RPM, Serpentine belt walking off pulleys, Knocking or wobbling sound from front of engine
Fix: Replace harmonic balancer and inspect crankshaft snout for damage. 2-3 hours labor. The rubber isolator deteriorates from heat cycling, and if it separates fully, you risk damaging the crankshaft sensor or worse.
Estimated cost: $350-650
Transmission Mount Deterioration
Common · low severityTypical onset: 40,000-80,000 mi
Symptoms: Clunking when shifting into drive or reverse, Excessive vibration through cabin at idle, Transmission housing visibly sagging or tilted
Fix: Replace collapsed rubber mount. 1.5-2 hours labor. The KF's vibration characteristics and constant gear hunting on hills eat these mounts. Not dangerous but annoying and accelerates driveline wear.
Estimated cost: $200-400
Buy one if you need a compact utility hauler for light-duty farm or warehouse work, but budget $2,000-3,000 for deferred engine work on anything over 60k miles — these trucks are reliable if babied, but most aren't.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.