What torque should be applied to the connecting rod bearing bolts?
2 Answers
Engine model varies, and so does the torque: 1. Size: The torque for the connecting rod bearing cap is smaller than that for the crankshaft bearing cap; 2. Source: Diesel vehicles generally require higher torque than gasoline vehicles; 3. Torque value: The specific torque required is usually determined according to regulations and the requirements specified in the manual. More relevant information is as follows: 1. Torque: For car cylinder head connecting rod cap and crankshaft cap bolts, the torque for the large bearing cap is 8, and for the small bearing cap, it is 6. The compression ratios of engines vary by vehicle model, so the bolt torque differs accordingly. A torque wrench can be used to measure the torque in Newton meters when removing the bolts. 2. Force application method: Divided into standard and reamed hole types. By head shape: Hexagonal head, round head, square head, countersunk head, etc. The hexagonal head is the most commonly used, typically for connections requiring fastening.
When I assembled the 1.6L engine of the old Jetta last time, I specifically checked the manual. The connecting rod bearing bolts require a step-by-step tightening method. First, pre-tighten all bolts to 30 Nm, then increase to 50 Nm one by one in sequence, and finally use an angle gauge to turn an additional 90 degrees. This procedure must be followed precisely. I've seen people take shortcuts by using an impact wrench directly, resulting in the oil pan being punctured at high speeds. The expansion coefficients of cast iron engines and aluminum bolts are different, so you must recheck the clearance after the engine warms up if tightened cold. If upgrading to reinforced bolts, extra caution is needed - you must purchase the matching torque data card.
