Thinking about buying a used Isuzu Bighorn (1991–2002) in New Zealand? We've documented 9 known faults for this model spanning body & rust, engine, transmission, and fluid leaks. Each researched and verified before it's published. The most serious issues here are rated critical. Two are set out in full below — the rest, with the symptoms, repair costs and checks for each, are free with an account.
9
Documented faults
Critical
Most serious
$700–$3,500
Typical repair
4
Systems covered
Known Isuzu Bighorn faults
Every fault below is documented specifically for this model — researched and verified before it’s published.
01Sill, Chassis Rail and Undercarriage Rust (NZ JDM Imports)
CriticalCommonBody & Rust $1,200–$6,500 to fix
JDM Bighorns imported to NZ from Japan frequently show rust perforation at the lower sills, chassis rail box sections, floor pan edges and rear spring hanger mounts. New Zealand's coastal humidity and salt exposure accelerates rust on vehicles that spent their early years in Japan's rust belt prefectures. Perforated chassis rails cause WoF failures and are expensive or impossible to repair economically.
Symptoms to notice
Visible rust bubbling under paint on lower sills
Hollow sound when tapping chassis rails
Flaking rust from undercarriage visible on inspection
WoF rejection for chassis integrity
What to check
Probe sill seams and chassis box rails with a screwdriver — soft or holed metal is a fail. Inspect rear spring hangers, floor pan edges, and wheel arch inners. Check for signs of underseal applied to conceal rust. If a workshop inspection is possible: Conduct a full underside inspection on a hoist.
Where to look: Lower sills, chassis rails, floor pan perimeter, spring hanger mounts, wheel arches
Ask the seller
“Has the undercarriage been inspected recently by a workshop?”
“Has any rust treatment or underseal been applied?”
“Does it hold a current WoF with no rust-related conditions?”
02Rear Differential Pinion Shaft Oil Seal Leak
MinorCommonFluid Leaks $200–$500 to fix
The rear differential pinion input shaft seal on UBS69 Bighorn examples frequently weeps or drips oil, particularly on high-mileage vehicles or those used for towing and light off-road. The neoprene seal lip hardens with age and loses effective contact. Oil loss at the pinion seal contaminates rear brake assemblies and, if ignored, causes differential bearing damage from low oil operation. The fault is consistent across the Bighorn, Trooper, and Jackaroo platform.
Symptoms to notice
Oil dripping or pooling under the rear centre of the vehicle
Oil wetness at the propshaft yoke where it enters the rear differential
Differential oil level low on inspection
Rear brake performance reduced or burning smell from oil on brake linings
What to check
Inspect the pinion flange where the rear propshaft connects to the differential for active oil weeping. Check differential oil level via filler plug. If leakage is visible, inspect rear brake drums or discs for oil contamination — this requires drum removal on drum-brake variants. Any oil near rear brakes should be treated as a brake safety concern.
Where to look: Rear differential pinion input flange, front face of rear differential housing
Ask the seller
“Has the rear differential been inspected for oil leaks recently?”
“When was the differential oil last changed?”
“Any oil drips under the rear of the vehicle or burning smell from the rear brakes?”
EngineCritical
EngineMajor
EngineMajor
TransmissionMajor
Body & RustMajor
TransmissionMajor
EngineMajor
7 more documented faults on the Isuzu Bighorn
Symptoms, what to check, where to look and what to ask the seller — for every fault above. Free with an account, no card needed. One account covers one vehicle, so make it the car you’re actually looking at.
This page covers the model. Enter the plate of the actual car you’re looking at and see its year, engine, safety rating and register flags — free, no account needed.
Like any used car, it depends on the specific example and its service history. Across the 9 documented faults for the Isuzu Bighorn, the recurring problem areas are body & rust, engine, and transmission. A Isuzu Bighorn with a full service history and no signs of the issues listed on this page can be a sound buy but each one needs to be checked individually before you commit.
What are the most common problems with a used Isuzu Bighorn?
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We've catalogued 9 known faults for the Isuzu Bighorn, covering body & rust, engine, and transmission. Two are written out in full on this page. The rest — with the symptoms to notice, what to inspect, and typical repair costs for each — are free once you create an account.
How much do repairs cost on a Isuzu Bighorn?
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Most single repairs on the Isuzu Bighorn fall between $700–$3,500 at NZ independent-workshop rates. Some of the 9 documented faults cost less and a few cost considerably more, and no one car needs them all. Knowing which ones to look for before you view is what lets you negotiate the price down or walk away.
Should I get a pre-purchase inspection on a Isuzu Bighorn?
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Yes. A Isuzu Bighorn inspection focused on its known weak points is the single best way to avoid an expensive mistake. KickTyres gives you a guided, model-specific inspection plus a market valuation and negotiation figure for $17.90 far less than the cost of missing one of the faults on this page.