An engine or a gearbox is the one purchase where it is worth being slow and asking a lot of questions. It is also where a wrecking yard saves you the most money, because a good used unit costs a fraction of a rebuild.
Ask what the donor vehicle died of
This is the whole question. An engine out of a vehicle that was hit in the rear is a completely different proposition from one out of a vehicle that was towed in because it stopped.
We list the damage on every vehicle on this site for exactly this reason. If the vehicle is here because of a crash, the engine was running the day before it arrived.
What to ask for
- The kilometres on the donor, and whether the odometer still read.
- Whether it was run, and whether anyone heard it.
- A compression test, on a diesel especially. Ask for the numbers, not for a yes.
- The engine code, which has to match yours. Not the size, the code.
- Whether the ECU and key came with it. On anything with an immobiliser, an engine without its ECU and key is a much harder job.
What to replace while it is out
Do the things that are cheap now and expensive later, because the engine will never be this accessible again:
- Cam belt and tensioners, if it has a belt. Always. Every time.
- Rear main seal and, on a manual, the clutch and spigot bearing.
- Water pump, thermostat and any hose you can reach.
The same logic applies to a gearbox: do the clutch while it is out.
Matching a gearbox
An automatic must match the engine, the transfer case and often the ECU. A manual is more forgiving but the bellhousing, the input shaft and the clutch still have to agree. Give us your engine code and what you are putting it in, and we will tell you what you need.
Be realistic about the job
A used engine is a good buy when you or your mechanic can fit it properly. It is a bad buy if it is going into a vehicle with other problems, because you will have spent the engine money and still not have a vehicle you trust.