Common Assembly Problems of Important Fasteners in Diesel Engines

There are many kinds of fasteners for diesel engines. Except for some special fasteners, most of them are standard fasteners. The special fasteners for the engine include: connecting rod bolts, cylinder head bolts, flywheel bolts, cylinder head nuts, main bearing bolts, etc. Diesel generator sets have high requirements for stability and reliability, so the assembly of engine fasteners is very important. During assembly, more attention should be paid and the torque of different fasteners of different fasteners should be grasped during assembly to ensure engine operation. Safe and reliable.

Diesel generator sets

 

       There are many kinds of fasteners for diesel engines. Except for some special fasteners, most of them are standard fasteners. The special fasteners for the engine include: connecting rod bolts, cylinder head bolts, flywheel bolts, cylinder head nuts, main bearing bolts, etc. Diesel generator sets have high requirements for stability and reliability, so the assembly of engine fasteners is very important. During assembly, more attention should be paid and the torque of different fasteners of different fasteners should be grasped during assembly to ensure engine operation. Safe and reliable.

 

       1. Cylinder head nut

       When tightening the cylinder head nut of diesel engine, it should be carried out according to the principle of first middle, last two sides, and diagonal crossing, and gradually tighten it to the specified torque in stages.

 

       2. Flywheel nut

       The flywheel nut of the diesel engine must be tightened, otherwise the diesel engine will produce a knocking sound, which will damage the crankshaft conical surface, shear the keyway, and twist the crankshaft in severe cases, resulting in serious accidents. Note that while tightening the flywheel nut, use the thrust washer to fold and lock it (the corner of the thrust washer can only be folded once).

 

       3. Connecting rod bolt

       The connecting rod bolts have to bear a lot of impact force during work, so they are all made of high-quality steel and cannot be replaced by ordinary bolts. When tightening the connecting rod bolts, the torque should be uniform, and the two connecting rod bolts should be gradually tightened to the specified torque several times in turn, and finally locked with galvanized iron wire.

 

       4. Main bearing bolts

       The installation accuracy of the main bearing should be ensured and not loose. When tightening the main bearing bolts (for the fully supported four-cylinder crankshaft), the 5 main bearings should be tightened evenly in 2 to 3 times in the order of the middle first, then 2, 4, and then 1 and 5. moment. Check whether the crankshaft rotates normally after each tightening.

 

       5. Rocker arm seat nut

       For the rocker arm seat nut, it should be combined with maintenance and regular inspection during use. If the rocker arm seat nut is loose, the valve clearance of the diesel engine will increase, the valve opening will be delayed, the closing time will be advanced, and the valve opening duration will be shortened, resulting in insufficient air supply of the diesel engine, unclean exhaust, power drop, and fuel consumption increase.

 

       6. Fuel injector lock nut

       When installing a diesel fuel injector, its lock nut should be tightened to the specified torque. At the same time, do not tighten it at one time, but repeatedly tighten it several times. Too tight or too loose will affect the performance of the unit.

 

       7. Oil outlet valve tight seat

       When installing the tight seat of the oil outlet valve of the fuel injection pump, it should also be carried out according to the specified torque. If the oil outlet valve seat is tightened too tightly, the plunger sleeve will be deformed, the plunger will be blocked in the sleeve, and the early wear of the plunger pair will be caused, the sealing performance will be reduced, and the power will be insufficient; if the oil outlet valve If the tight seat is too loose, the fuel injection pump will leak oil, the oil pressure cannot be established, the fuel supply time will lag, and the fuel supply will be reduced, which will seriously affect the engine performance.

 

       8. Injector pressure plate nut

       When installing the fuel injector assembly on the cylinder head of the diesel engine, in addition to removing dirt such as carbon deposits in the mounting seat of the fuel injector assembly, the pressure plate of the fuel injector assembly should not be installed backwards, and the thickness of the steel pad should be appropriate and cannot be missed. , and also pay attention to the tightening torque of the pressure plate nut of the injector assembly. If the tightening torque of the pressure plate nut is too large, the valve body of the injector will be deformed, the fuel injector will be stuck, and the diesel engine will not work; if the tightening torque is too small, the fuel injector will leak air, resulting in insufficient cylinder pressure and difficulty in starting the diesel engine. , the high temperature gas will also rush out and burn out the fuel injector.