Toyota Hilux KUN26: common faults & what to check

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The Euro IV version of the 3.0 1KD-FTV turbo diesel in the KUN26 Hilux is known for cracking pistons, most often between 100,000 and 150,000 km. Toyota acknowledged the problem in service bulletins (EG-0172T-0511 and EG-0008T-0112) and fitted stronger pistons and improved injectors, with Australian Hilux engines from July 2014 (engine number A477120 on) getting the fix. There is no recall or extended warranty now. A cracked piston usually means a full engine rebuild or replacement engine, so proof of new pistons or a replacement engine adds real value.

Where to look: Engine internals (pistons), checked through the oil filler and exhaust

Parts involved: Fuel injector, Turbocharger.

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The 2.4L 2GD-FTV engine in high-mileage AN120/AN130 HiLux units above 150,000km develops excessive oil consumption due to worn piston rings or deteriorated valve stem seals. The piston ring wear is accelerated in vehicles with infrequent oil changes or extended service intervals, and in units that have operated with a clogged DPF causing oil dilution from excessive fuel injected during failed regeneration events. Affected engines consume 500ml to 1.5 litres of oil per 1,000km. Symptoms include blue smoke on acceleration, low oil level warnings between services, and carbon fouling on spark plugs and injector tips. A full engine rebuild or short engine replacement is typically required at this stage.

Where to look: Engine internal - pistons, rings, and valve stem seals throughout engine block

Parts involved: Fuel injector, Diesel particulate filter.

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The 1KZ-TE's EGR (exhaust gas recirculation) system recirculates hot exhaust gases back into the intake, which causes progressive carbon buildup on the EGR valve, inlet tract, and intake ports. A stuck-open EGR valve causes excessive exhaust gas dilution of the intake charge, raising combustion temperatures beyond design limits. Sustained high combustion temperatures crack the aluminium pistons — an expensive internal engine failure. Many owners eliminate the EGR system entirely as a preventive measure; a blocked or removed EGR is therefore not automatically a red flag and should be verified.

Where to look: EGR valve on the exhaust/intake crossover pipe, top of engine; pistons inside the engine block

Parts involved: EGR valve.

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Early GUN125/126 HiLux vehicles built from late 2015 through 2017 were subject to documented concerns around premature timing chain stretch and tensioner wear in the 2GD-FTV engine. The chain drive system, under high-cycle towing and load use without strict early oil change adherence, stretched faster than the tensioner could compensate. Affected vehicles showed timing retard, rough running, and in some cases jumped timing. Toyota Australia issued service guidance and an extended warranty programme covering affected early-production vehicles.

Example of the part — not this vehicle

Where to look: Front of engine — timing chain, tensioners, and guide rails inside the timing cover

Parts involved: Timing chain.

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The EGR cooler on the 2GD-FTV engine is prone to internal matrix cracking, particularly in high-cycling urban use where repeated heating and cooling fatigues the cooler. When the cooler fails, coolant leaks internally into the EGR system and is introduced into the intake manifold and combustion chambers. Coolant in the intake causes white exhaust smoke and hydrolock risk if severe. Externally the coolant loss from the EGR cooler is subtle, and the system may overheat before the fault becomes obvious.

Where to look: Engine — EGR cooler mounted on the intake manifold side, coolant lines connecting from the engine cooling circuit

Parts involved: EGR valve.

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The 2.8L 1GD-FTV injectors are prone to seizing in the cylinder head due to carbon lock between the injector body and the head bore. Removal without the correct extraction tooling frequently damages the head threads or pulls the copper sleeve, requiring head replacement. Toyota issued a Technical Service Bulletin on injector removal procedures. Failed injectors cause misfires, excessive smoke, and fuel dilution of oil.

Example of the part — not this vehicle

Parts involved: Cylinder head, Fuel injector.

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The EGR cooler on the 2.8 litre 1GD-FTV diesel is a known issue for developing fatigue cracks inside, so coolant leaks into the intake or exhaust instead of dripping on the ground. The first sign is usually a coolant level that keeps dropping with no visible leak, and if it is ignored the engine can overheat. Toyota issued a technical bulletin (EG-00635T-TME) for the same 1GD-FTV engine in the Land Cruiser Prado, replacing the EGR pipe and cooler with a revised part, and Hilux owner reports put failures mostly past 150,000 km. Some cars have had the cooler replaced under warranty or goodwill, so ask for the paperwork.

Where to look: EGR cooler and pipe on the engine, between the exhaust manifold and the intake, under the bonnet

Parts involved: EGR valve.

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The 6-speed automatic transmission fitted to AN120 Hilux develops solenoid wear in the valve body, causing delayed engagement, gear hunting, and occasionally harsh or erratic shifts. The failure mode is accelerated by infrequent transmission fluid changes or heavy towing use. Toyota issued internal workshop guidance on inspection and fluid service intervals to address this pattern.

Where to look: Automatic transmission — valve body inside the gearbox oil sump

Parts involved: Mechatronic / valve body.

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The 1GD-FTV EGR system accumulates carbon deposits that restrict flow and cause valve sticking, triggering fault codes P0400-range and limp mode. Intake manifold cleaning is required alongside valve replacement to prevent recurrence.

Parts involved: EGR valve.

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The petrol four-cylinder Hilux of this era drives its cam with a single-row chain running on plastic guides, and both wear with age and kilometres. The first sign is a rattle for a few seconds on cold start while the tensioner takes up slack, growing over time into a constant rattle; a broken guide lets the chain slap the case and in the worst case jump timing. NZ owner communities treat chain, guides and tensioner as an expected job on high-kilometre examples. It is a different noise from the cracked exhaust manifold tick these engines also suffer — manifold tick is loudest under load, chain rattle is worst at cold idle.

Example of the part — not this vehicle

Where to look: Front of the engine — timing chain case behind the radiator fan

Parts involved: Timing chain.

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HiLux models fitted with the 1GD-FTV 2.8L engine and SCR emissions system use an AdBlue (diesel exhaust fluid) dosing pump with an integrated heating element. The heater prevents AdBlue crystallisation in cold weather and keeps the pump and lines operational. The heating element fails with age and exposure, particularly in units that have experienced freeze-thaw cycles. A failed heater results in AdBlue crystallisation inside the pump, blocking the dosing injector. The vehicle ECU detects insufficient reductant dosing and triggers a NOx derate warning. If not rectified within the allowed grace distance the engine is electronically restricted to a maximum speed of approximately 25km/h. The complete dosing pump assembly must be replaced.

Where to look: AdBlue dosing pump and SCR system, underside of vehicle near rear axle

Parts involved: Fuel injector.

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Toyota recalled Hilux utes built in 2018 and 2019 because a piston in the brake pedal assembly can break after repeated pedal use. If it breaks, the driver loses braking assistance and the ute needs far more pedal effort and a much longer distance to stop. The remedy is free at a Toyota dealer and quick, but recall completion on used utes is patchy - work vehicles that have never gone back to a franchise dealer are the ones most likely to still be outstanding. Campaign coverage and the campaign code vary between markets, so the only reliable answer comes from running this ute's VIN through the local Toyota or transport agency recall lookup rather than assuming it was handled. This is a separate item from the brake booster vacuum hose that chafes through on these utes - that one is wear, this one is a recalled part with a free factory fix.

Where to look: Brake pedal assembly under the dashboard on the driver's side.

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Toyota issued a Technical Service Bulletin in 2019 documenting brake booster vacuum hose chafing on AN120 Hilux diesel models. The hose runs in a location where it contacts the engine or chassis, wearing through the outer casing over time. A damaged or collapsed hose reduces brake booster assistance, increasing pedal effort and reducing stopping performance — a direct safety concern.

Where to look: Engine bay — brake booster vacuum hose running from brake booster to intake manifold or vacuum pump

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LN-series Hilux from 1984 to approximately 1997 used a solid front axle with kingpins and swivel hub bearings. LN167 and later models switched to independent front suspension with conventional upper and lower ball joints. Both designs develop significant wear at high mileage. Worn kingpins allow wheel wobble and are a common WoF failure; worn IFS ball joints cause clunking and vague steering.

Example of the part — not this vehicle

Where to look: Front axle — swivel hubs and kingpins on pre-LN167 solid-axle models; upper and lower ball joints on IFS models (LN167 onwards)

Parts involved: Ball joint.

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A batch of 2015-2016 Hilux left the factory with the drain holes in the bottom of the doors either plugged with plastic blanks or filled with sealer, and those plugs were meant to be taken out before the ute was handed over. Where that never happened, water from rain, washing or a creek crossing collects inside the door skin with nowhere to go. Owners notice it as water sloshing in the door when they open and shut it. Left alone the water sits against the bottom of the door skin and rusts it from the inside out, which in New Zealand eventually becomes a warrant of fitness problem and a panel bill. The fix costs almost nothing if it is caught early and a great deal once the metal has gone.

Where to look: Bottom edge of each door, inside the door skin below the trim card.

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The front strut top mount bearing on AN120 and AN130 HiLux models is a known wear point. The bearing allows the strut to rotate during steering inputs. Under the load conditions typical of ute use including rough terrain, heavy payloads, and off-road driving, the bearing races and retainer degrade from approximately 60,000-100,000km. Failed bearings produce a pronounced clicking or clunking sound when driving over bumps or when turning at low speed. The noise is often mistaken for CV joint or ball joint failure. Replacement requires removal of the strut assembly and is straightforward but both sides typically fail close together.

Where to look: Front strut top mount, inside engine bay at each front suspension turret

Parts involved: Shock absorber / strut.

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The GUN125/126 HiLux rear suspension uses a traditional multi-leaf spring setup with rubber shackle bushes at each spring end. The rubber bushes in the rear shackle compress and take a permanent set under repeated loaded use — towing, utility bed loads, farm work. The resultant wear causes the axle to shift fore-aft under braking and acceleration, producing a clunk. Worn shackle bushes cause axle wrap under hard acceleration and vague handling when loaded. A common fault on working HiLux that regularly carry payload at or near GVM.

Where to look: Rear suspension — leaf spring front eye bush and rear shackle bush, both sides

Parts involved: Rear leaf spring.