While used Japanese engines made for the Japanese domestic market (JDM) are famously well maintained in accordance with Shaken regulation, they should be tested prior to purchase. Testing is important because it lends validity to engine age, mileage, and quality. At a minimum, compression and leak down tests should be performed.
Used Japanese Engine Compression and Leak down testing
Compression and leak down tests are often done in conjunction, but there is a difference in these tests. The compression test (CT) measures the compression created when the piston moves from bottom dead center (BDC) of the cylinder to top dead center (TDC). The leak down test measures the loss of compression when the piston is at TDC. Instead of measuring the pressure generated while the engine is running, the leak down test measures pressure lost when air is fed into the cylinder of a resting motor.
Leak down tests are performed on used Japanese engines because it takes less time to find out whether or not the engine is good. Escaping air makes noise, and the location of the noise will identify the problem spots rather quickly. Escaping air can identify issues such as worn intake valves, rings, and cylinders. Compression leakage in the 5% to 10% range indicates a used JDM engine that is in excellent condition. Engines with 10% to 20% compression leakage are considered to be very good.
Using the leak down and compression test results together is a primary diagnostic tool to determine the quality of a used engine. The results of the tests can indicate both minor and major problems. For example, low compression with minimal leakage is indicative of incorrect timing (minor) or a major issue such as a warped push rod.
Used JDM Engine Oil Pressure testing
Maintaining the correct oil pressure is important to engine life. Metals moving against one another create friction, which breaks down the metals and causes engine wear. Oil lubricates the engine’s moving parts so that metals don’t touch. Sufficient oil pressure is important to the oil’s circulation throughout the engine.
It is important to check the oil pressure of a used Japanese engine. If the oil pump, filter, and oil injectors are good, low oil pressure may indicate crankshaft bearing wear. On the other hand, high oil pressure may be caused by engine buildup which blocks proper oil circulation.
The benefit of purchasing a JDM engine is generally the engines have low mileage and minimal wear. This means that the cylinder health is more than likely good to excellent. Because of Japanese regulations require significant testing and inspection on all vehicles navigating the roadways, any engine problems are immediately fixed instead of further damaging the motor. Used motors imported from Japan are famous for having good compression with minimal leak down.
Engine World INC has one of the largest inventories of used Japanese engines available in the United States and Canada. We know that receiving the best used engine available is important to our customers. We take pride in our used JDM engines and strive for 100 percent customer satisfaction. We pioneered the Ultra 5 test, so all our engines have been meticulously tested and inspected to ensure our customers receive the finest quality used motor.
