How to Spot a Quality Used Engine Before You Buy

Buying a used engine can save real money over a new or crate replacement, but only if the engine you get home actually runs the way it should. A little care before you hand over payment saves a lot of grief after the tow truck pulls away, and most of that care doesn't take a mechanic's toolkit, just the right questions.

Start with the donor vehicle, not just the engine

A used engine did not arrive from nowhere. It came out of a real car, truck or SUV that was running, or at least turning over, before it was pulled. Ask what kind of vehicle the engine came out of and why. An engine pulled because the rest of the car was wrecked in a way that had nothing to do with the drivetrain is a very different story from one pulled because it was already smoking or knocking. A yard that keeps good records on its donor vehicles should be able to tell you this without hesitation.

Listen and look before you commit

If you can see the engine running, or at least hear it turned over, do it. A healthy engine idles evenly and doesn't hunt for its rpm. A few things are worth checking with your own eyes and ears before money changes hands:

• Pull the oil filler cap and look for a thick, milky residue, a sign coolant has been mixing with the oil
• Check the coolant itself for any trace of oil floating on top
• Listen for knocking, ticking or rattling that changes with engine speed
• Watch the exhaust for blue smoke, which means burning oil, or thick white smoke that doesn't clear
• Confirm the sensors, brackets and accessories your vehicle needs are actually still on the engine, not sold separately

Match the engine code, not just the model name

Two engines can share a model name and still not be a good swap for your vehicle. Mounts, sensor locations, accessory brackets and even the bolt pattern to the transmission can change across model years. Before you buy, get the engine code or casting number off the block if you can, and compare it against what your vehicle actually calls for. A yard with real vehicle history on file can usually confirm the code without you needing to climb into the engine bay yourself.

Mileage tells only part of the story

A lower-mileage engine is generally a safer bet, but mileage alone doesn't tell you how the vehicle was driven or maintained. An engine with more miles that was serviced on schedule can easily outlast one with fewer miles that ran low on oil for years. Ask what you can about service history, and treat the mileage number as one input, not the whole answer.

Ask about the warranty before you ask about the price

A used engine is still a used part, and the warranty terms tell you a lot about how confident the seller actually is. At our yard, mechanical parts carry a 90-day limited warranty, and the engine warranty specifically covers replacement of a defective long block, meaning the block itself, the crank, pistons, connecting rods and the complete heads and assembly. It does not extend to intake or exhaust manifolds, gaskets, oil pans, the distributor, alternator, A/C compressor, power steering pump, fuel pump, carburetor, fuel injection parts, spark plugs, filters or the water pump, and the engine needs to be installed by a certified mechanic for the warranty to be effective. Read whatever a yard hands you before you sign, and ask what happens if something goes wrong.

A yard that tests before it sells is doing some of the work for you

Every part that leaves our counter at 328 Patterson Rd in Joliet has already been tested before it's offered for sale, which takes some of the guesswork off your plate. If you're not sure an engine is the right fit for your exact year, make and model, call ahead and ask, or bring the VIN with you. We also offer free estimates within one to two days if you'd like a number before you commit to anything. A used engine bought carefully, with the donor history checked, a real look under the cap and a clear warranty in hand, is one of the better ways to get a vehicle back on the road without paying crate-engine money.