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Toyota 1HZ engine: known problems
Used in 4 guides · diesel · 9 known problems
Fuel
diesel
Known problems9
Everything our guides list for the variants with this engine: the engine itself plus the gearbox and ancillaries it's paired with. Each shows which cars it's listed for.
High
Cracked cylinder head from overheating / poor turbo conversions
The 1HZ head is reliable when the engine is left near stock and the cooling system is healthy, but it cracks between the valve seats if overheated or pushed with an aggressive aftermarket turbo and no intercooler/EGT management. Coolant loss and white smoke are the warning signs.
Fix: Keep the cooling system fresh; on turbo'd examples fit an intercooler and watch EGTs. Replace or recondition the head if cracked, ideally with an updated head.
Listed for: Toyota LandCruiser 80 Series · Toyota LandCruiser 70 76 Wagon / 78 Troopcarrier
Medium
Injector pump wear
Mechanical injection pump and injectors wear at very high km.
Fix: Diesel-specialist pump/injector rebuild.
Listed for: Toyota LandCruiser J100 · Toyota LandCruiser 80 Series · Toyota LandCruiser 70 76 Wagon / 78 Troopcarrier
Medium
Overheating if cooling neglected (esp. aftermarket turbo)
The NA 1HZ runs cool and reliable; many are turbo'd aftermarket, which can cause head/cooling stress if done cheaply.
Fix: Verify any turbo install (intercooler, EGT/boost gauges); maintain cooling system.
Listed for: Toyota LandCruiser J100
Medium
Cracked exhaust manifold (turbocharged conversions)
Aftermarket turbo conversions stress the cast iron exhaust manifold which can crack.
Fix: Upgraded manifold. Worth doing pre-emptively if buying a turbocharged 1HZ.
Listed for: Toyota LandCruiser 70-Series
Low
1HZ injector pump timing (very high km)
1HZ rarely fails but injection pump can drift on very high km units.
Fix: Pump re-time by diesel specialist. Inland Australia has dozens of these specialists.
Listed for: Toyota LandCruiser 70-Series
Low
Glow plug failure
Glow plugs fail individually - hard cold starts.
Fix: Replace as a set. Easy DIY.
Listed for: Toyota LandCruiser 70-Series
Low
Front swivel hub seals
Same as Patrol - swivel hub oil leaks.
Fix: Reseal kit. Weekend job.
Listed for: Toyota LandCruiser 70-Series
Low
Tired ancillaries and age-related wear
These are 25-35 year old vehicles - perished hoses, weeping seals, worn bushes and a tired radiator are the norm.
Fix: Budget for a consumables refresh on purchase.
Listed for: Toyota LandCruiser 80 Series
Low
Age-related ancillaries and oil leaks
These engines are decades old; expect rear main/front seal weeps, perished hoses, tired mounts and a slow oil drip somewhere.
Fix: Budget a consumables and seal refresh on purchase.
Listed for: Toyota LandCruiser 70 76 Wagon / 78 Troopcarrier
Cars with the 1HZ4
From the FlamingCars guides for these cars. Specs are shown only where the guides agree and the value is verified.