How To Check A Used Motor

As I move forward in my quest to build cars for a living, or to just have a couple of project cars under my belt, I have found that motor swaps are very expensive.  Some are cheaper than others, but for any swap that you would really want to do, a decent sum of cash is needed.  If you are into imports, used motors for Japanese sourced cars can run as high as $6000 or more for an entire swap.  Purchasing a crate motor from GM will run you at least $1800, and that is just for the motor, you will most likely still need to purchase and intake manifold, headers, and all the accessories.  You would either need to source them or have the car with a similar engine already available to do it.

That being said, used motors are going to come into play.  Depending on what kind of motor you are looking for, you can find them online at JDM engine shops, EBay, or even Craigslist.  You can also go the old school route of simply going to a junk yard and finding one for yourself.  For browsing and pricing purposes, I have been a fan of Craigslist since most junk yards do not have an online inventory.

Unfortunately there isn’t much that you can do to check out these used motors before you purchase.  You pretty much have to take the seller at their word that the engine is OK.  However, there are a couple of things that you can do to gain some assurance that the engine is in decent condition and give you some piece of mind in the process.

If you need to check quickly and removing parts from the engine is not an option, bring a flashlight.  Do a physical inspection of the engine, check for any obvious cracks or physical damage to it.  Remove the oil cap and shine the flashlight in there.  If it’s nice and clean, it’s most likely a good engine.  If it’s dirty and filled with grime and dirt, take a pass.  Otherwise following the suggestions below will assure you even more.

Pull the spark plugs and look for abnormal wear.  If there is a lot of buildup on the plugs, most likely the motor has some kind of issue and you will want to avoid it.  Also, while the plugs are out, rotate the crank to see if the engine spins freely.  If it does not, there is some kind of mechanical issue.  Now put the plugs back in and see if the engine is harder to turn, it should be.  If it is not or it is choppy in its spinning, there may be a loss of compression in one or more of the cylinders.  This is not an exact science but you should notice issues while turning the crank.

Remove the valve cover and look for signs of overheating, some used motors will have been pulled just for this reason!  If you are in a junk yard and your car looks undamaged, this is a distinct possibility.  You can also pull the oil pan and look for the same thing.  Black color on the rod caps will be a tell tale sign of overheating.  While the oil pan is out, you should pay attention to any metallic flakes that may be present; this can be a sign of bad bearings somewhere in the motor or even something much worse.


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