First, Decide Whether Replacing Is Even the Right Move
Before you shop for an engine or a transmission, be honest about the car it is going into. Three numbers decide this:
If the fitted cost plus the next twelve months of spend exceeds the car's running value by a decent margin, replacing the engine is a sentiment decision rather than a financial one. That is a legitimate choice, but make it knowingly. Our condition assessment and price guide will help you put a number on the running value, and signs your car is not worth repairing covers the decision in more detail.
If the numbers do not work, selling as-is is usually better than sinking money in. We buy vehicles with failed engines and transmissions every week through cash for cars.
Used, Reconditioned, or Exchange? They Are Not the Same Thing
The terminology gets used loosely and it matters.
| Option | What you get | Warranty typically | Best for |
|---|---|---|---|
| Used / second-hand | Untouched unit from a donor vehicle | Shortest | Lower-value cars, tight budgets |
| Tested used | Donor unit that has been run and pressure or leak tested | Short to medium | Most common sensible choice |
| Reconditioned | Stripped, machined, new wear components fitted | Longest | Cars worth keeping long-term |
| Exchange | Recon unit supplied against your old one as a core | Longest | Common engines with good core value |
A cheap untested used engine and a reconditioned unit are not competing products. Compare like with like, or you will pick the wrong one on price.
What to Verify Before You Pay: Engines
Donor kilometres, and evidence of them. Ask for the donor's reading and why it was dismantled. "Front-end damage at low kilometres" is the ideal answer. No answer at all is a red flag.
Exact engine code, not just the model. Manufacturers change engine variants mid-model, sometimes mid-year. The engine code stamped on the block is what matters, along with build date. Getting this wrong is the most common expensive mistake.
What comes with it. Does the price include the intake manifold, injectors, turbo, alternator, starter, sump, loom, sensors, flywheel? A "long motor" and a "complete engine" are very different purchases.
Compression or leak-down results. Ask whether it has been tested and how. A number is worth far more than an assurance.
Turbo condition, if fitted. Shaft play, oil in the intake, and whether the turbo is included at all.
Timing components. If the engine uses a belt, plan to replace it during fitment regardless of what you are told. If it is a chain, ask about noise and whether the tensioner is known to fail on that engine.
Oil and coolant history. Sludge inside the rocker cover indicates neglect. Ask for a photo under the oil cap.
What to Verify Before You Pay: Transmissions
Exact transmission code and gear ratio. Same-model cars often ran two or three transmission variants. A mismatch can mean anything from wrong shift behaviour to physical non-fitment.
Whether it is matched to your engine, drivetrain and body style. Two-wheel versus four-wheel drive, and often manual versus automatic housings, are not interchangeable.
Automatic fluid condition. Dark brown or burnt-smelling fluid is a hard no. Clear red or amber is what you want.
Torque converter included? On automatics this is a significant cost if it is not.
Whether the control module needs to travel with it. Many modern automatics are adaptively coded to the vehicle. Ask whether the transmission control module is included and whether it needs coding after fitment. This catches out an enormous number of buyers.
Case condition. Cracks around the bell housing and stripped bolt holes are common on damage-salvage units.
CVT and dual-clutch units specifically. These are far less forgiving second-hand than a conventional automatic. If your car has one, weigh a reconditioned or exchange unit much more seriously.
Warranty Terms: Read These Words Carefully
A warranty on a used engine or gearbox usually covers the unit itself, not the labour to fit it a second time, and not consequential damage. Ask directly:
- Duration and kilometre limit.
- Does it cover labour to remove and refit, or parts only? Parts-only is the norm. Know it upfront.
- Does it require fitment by a licensed workshop with an invoice? Almost always yes. DIY fitment voids most of them.
- Are there mandatory service conditions? Oil and filter at a set interval, correct fluid specification, cooling system flushed.
- What is explicitly excluded? Overheating, oil starvation, incorrect fluid, and pre-existing faults in your car that damage the new unit are standard exclusions.
- Is any of it in writing? If it is verbal, it does not exist.
- Timing belt, tensioners and idlers, plus the water pump if it is belt-driven.
- All engine and transmission oil seals accessible during fitment, especially the rear main.
- Clutch, thrust bearing and spigot bearing on a manual, every time.
- Engine and transmission mounts.
- Thermostat, radiator hoses and coolant. A marginal cooling system is the fastest way to destroy a replacement engine.
- Oil cooler lines and, on an automatic, a transmission cooler flush. Debris from the old failed unit will circulate straight into the new one.
- Spark plugs, ignition leads, filters, fresh fluids to the correct specification.
- The seller cannot or will not state the donor vehicle's kilometres.
- No part or engine code is offered, only "it fits your model".
- The unit is dramatically cheaper than every other quote with no explanation.
- Warranty is verbal only, or the terms will be "sorted out later".
- No returns under any circumstances, including wrong fitment.
- Photos only from flattering angles, and no photos of mating faces or connectors.
- Pressure to pay a deposit immediately to "hold" it.
- The unit itself.
- Freight, which on an engine or gearbox is substantial and sometimes needs a tailgate truck or depot pickup.
- Removal and fitment labour, usually a full day or more.
- The ancillary parts listed above.
- Fluids.
- Diagnostic and coding time on modern vehicles.
- A contingency, because something seized or snapped is normal on an older car.
The uncomfortable reality: most warranty claims on used drivetrain units fail because the cause of failure was something in the buyer's car, not the part. Which leads to the next section.
Fit These at the Same Time or Regret It
The part is not the whole job. Replacing these during fitment is cheap; replacing them afterwards means doing the labour twice.
The single biggest cause of a replacement engine failing early is an unresolved cooling problem in the car it went into. If the original engine overheated, find out why before you fit another one.
Red Flags That Should End the Conversation
What This Actually Costs, Realistically
The part price is often less than half the total. Budget for:
Get the workshop to quote the whole job, not just the fitting hours, before you buy the part.
Where to Start
Browse our tested second-hand engines, gearboxes and mechanical parts, or start from your make: Toyota, Holden, Ford, Mazda, Nissan, Hyundai, Subaru, Mitsubishi, Isuzu, Volkswagen, BMW and Mercedes-Benz. Regional buying guides are available for Brisbane and the Gold Coast.
If the numbers say the repair is not worth it, the instant quote page will tell you what the car is worth as-is instead.
Frequently Asked
Is a used engine with 150,000 km a bad buy?
Not automatically. A well-serviced engine at 150,000 km can be a better buy than a neglected one at 90,000 km. History matters more than the number alone.
How long should the warranty be?
There is no legislated minimum, and terms vary widely. What matters more than the headline duration is whether it is in writing, whether it covers labour, and what voids it.
Can I fit it myself?
Mechanically, sometimes. Contractually, it usually voids the part warranty, and on a modern vehicle you may still need a workshop for coding. Check the warranty terms before you decide.
Does a used automatic need to be coded to my car?
Often yes on modern vehicles. Ask whether the transmission control module is included and what coding is required, because this is a real cost that people forget.
My engine is gone and the repair is not worth it. What now?
Sell it as-is. We buy non-runners across Australia with free collection through cash for cars.