Single‑Use Design, Graded Selection & Warranty Protection
Crankshaft main bearings are single-use precision components and must never be reused after removal, as they will have lost their designed crush and conformability. When replacing bearings, Isuzu service procedures mandate measuring each main bearing housing bore and crankshaft journal to select the correct bearing grade (marked with a grade number such as “1,” “2,” “3,” or “4” which corresponds to a specific color code) from the standard set. A mis-matched or non-genuine bearing results in either excessive oil clearance (causing low oil pressure, knocking noise, and crankshaft journal damage) or insufficient clearance (leading to bearing seizure and catastrophic engine failure). After installing new bearings with engine oil applied to the bearing surfaces and cap bolts, the main bearing cap bolts must be tightened progressively in the specified sequence from the center outward to the factory torque value, with 166 N·m (122 lb·ft) being correct for many Isuzu 4JJ1 applications. Using a non-genuine or reused bearing set will void your Isuzu engine warranty. Choose genuine to restore factory-specified oil clearance and bearing crush, protect your rotating assembly from crankshaft journal damage and catastrophic failure, and ensure the long-term reliability your Isuzu engine was designed to deliver.