Buyng a used engine from the junkyard id a cheaper alternaive than a brand new engine. First yo shoukd determine that the engine in your car or truck is in need of replacemnt. Several differtn tests shoud be done to your old engine. I would recommend listening toi the old engine with or without a mechaniclal stethescope. This is very similar in stylr to the one used by a nurse or a dolctor. The only difference is that a mechanics stethescope has a s=thin metal shaft on it to allow you to listen like the medical profession listens when you visit your dr. The mechanic listne to the cam or crankshaft of the suspected bad engine. It is also recommended that the engine accessories such as the alternaor powe steering or air conditioning compressor be looked at. This is done to be sure that they are not the cause of the sounds in the engine area. Once you have determined that your engines belt driven acessories are not the vcause of your problem listen to the valve cover area with your tool . It is also suggested that you perform a compression test on your old engine. This procedure involves removing the coil packs and unpluging them from the engine harness. The spark plug is removed. A threaded rubber hose is placed in each spark plug hoe. As easch plug is removed and the reading checked they should be written down. Normal compresion for a modern car engine should be 115 pundas or more on the tool. if the compression is less especiallly in 2 or more cylinders it is sugested hat the engine be replaced, Other test can be performed with a auotmotive sscan tool. Your resdig from the scan tool on your engfie should be compared to a non damaged engone. If after all of the tests you have a damaged engine you should call several local auto parts yards. You will neeed o give them the year make and model of your car, The price of the used engine is usually 1/4 or 1/3 that of a brand new engine As an exsmle we own a 1987 Dodge Aries. At a local junkyard the price of a used engine for my car was $350. Fir a remanufactured engine the price was 2100.00 for a 1987 Aries or Relient. The used juunkyard engine shpuld have a 30 day or 100 mile warrasnty with it. THe person buying the engine should hear the engine before buyinbg. In my view the junkyard enginthat the yused engine be installed due to it much klowe costs.