CriticalCommonBody & Rust

Isuzu Bighorn: Sill, Chassis Rail and Undercarriage Rust (NZ JDM Imports)

Sill, Chassis Rail and Undercarriage Rust (NZ JDM Imports) is a common body & rust fault on the Isuzu Bighorn on the 1992–2002 cars, and we rate it critical. Putting it right costs $1,200 to $6,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 12 documented faults on the Isuzu Bighorn.

Vehicle: Isuzu Bighorn
Years: 1992–2002
System: Body & Rust

This page covers the Isuzu Bighorn as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Isuzu Bighorn faults12 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Chassis and structural rust yet. We would rather show none than show a picture of a different part.

What goes wrong

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.

What you would 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

How to check it

Where to look. Lower sills, chassis rails, floor pan perimeter, spring hanger mounts, wheel arches

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.

Parts involved: Chassis and structural rust.

What it costs to put right

$1,200 to $6,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

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?”

Now check the Isuzu Bighorn you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Isuzu Bighorn buyer questions

Is sill, chassis rail and undercarriage rust (nz jdm imports) serious on a Isuzu Bighorn?

We rate it critical and common on the Isuzu Bighorn. 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.

How much does it cost to fix on a Isuzu Bighorn?

$1,200 to $6,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Isuzu Bighorn years are affected?

Our research records this fault on the 1992–2002 Isuzu Bighorn. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

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. Look here: Lower sills, chassis rails, floor pan perimeter, spring hanger mounts, wheel arches