4. Reasons and Solutions for Common Faults of Cummins Diesel Engine

As we know, diesel engine is very important for diesel generator set. In generally, engine is not easy to damage or have faults, but when it has faults, this will be a serious problem. When the self-diagnosis system does not output fault codes, it is particularly necessary to rely on operator's inspection and judgment to determine the nature of fault and the location of the fault. In this article, we mainly shares some reasons and solutions of common faults of Cummins diesel engine.

1.Diesel engine starts difficultly or can not start up, a lot of white smoke is discharged from the exhaust pipe.

When the engine starts, the exhaust pipe discharges a lot of white smoke, in generally it is not the fault of fuel supply system.

The reason:

A.There is water in diesel oil. Water evaporates into steam in cylinder and is discharged from exhaust pipe.

B.Cylinder head bolt becomes less crowded or air cylinder gasket washout, so that cooling water gets into the cylinder

C.There is trachoma or crack somewhere in the cylinder block or cylinder head. Water enters the cylinder and evaporates and discharges.

Methods of resolution: 

A.Approaching the outlet of exhaust muffler by hand, if there are droplets of water in the wet hands, it is confirmed that water enters the cylinder.

B.Check whether there is water in diesel fuel or not. Check whether there is a large amount of water in the oil-water separator or not, if there is a large amount of water, the fuel quality is poor. First of all, the water in the high and low pressure oil pipeline should be removed; then, the discharging screw plug of the tank should be opened to discharge the water in the tank; finally, the tank should be washed with clean diesel oil.

C.Open the water tank cover, press the starter button while observing whether there is bubbles on the water surface of the nozzle. If there is water in the oil or bubbles on the water surface of the nozzle, the cooling water enters the cylinder block.

D.Further look for the specific leak location, can aerate into the tank, pressure is not more than 200 kPa, open the oil pan, inspect the leak at the bottom of the engine; then open the cylinder head to inspect the bottom of the cylinder head and the cylinder gasket and inspect the fault location. For the parts leaking in the directional cylinder, the method of replacement repair or replacement of new assembly is adopted.

2.Diesel engine is difficult to start up in hot tart

The engine is good in cool tart, but after starting a while, the temperature rises, then quenching, it is difficult to start again.

The reason:

It is mainly caused by serious wear and tear of plunger pair and needle valve pair of fuel injection pump. When the engine starts in hot tart, because the temperature of the fuel injection pump and fuel filter is higher, the fuel viscosity decreases, and the starting speed is lower, most of the diesel oil leaks from the wear gap, resulting the starting oil is insufficient to start.

Methods of resolution:

When the plunger pair or needle valve pair is seriously worn out, should replace new product after checking and debugging of the injection pump test bench.

3.There is crackle on cylinder block and cover or the cover leaks water

This will seriously affect the service life of the engine, so should check clearly for this fault.

The reason:

A.Causing seep through because of unsuitable operating. For example, adds cooling water into the engine when in high temperature, or when the engine starts in severe winter, suddenly adds high temperature water into it, or does not use antifreeze and rust-proof fluid according to the regulations, which causes cylinder block and cylinder head to burst, or causes cracks in expansion and extrusion water plug, resulting in corrosion of water plug cover and leakage of cavitation corrosion.

B.Insufficient disassembly and repair. Having not tight cylinder head bolts in the prescribed order, method and moment, causing uneven force or cracks in cylinder block and cylinder head caused by impact; or inadequate installation and deflection when replacing water plug cap.

C.If sand holes and aging treatment is solved unsuitable, concentration of thermal stress or large residual stress in casting, will cause leakage of cylinder block and head.

Methods of resolution:

A.Check whether there are cracks in the cylinder block or head, or the leaking part of a water plug cap. The pressure test of cooling system can be carried out by using the water pressure of 280kPa to 390kPa, found out the crack location. Different repair methods are adopted for different parts.

B.Welding repair can be used when the crack is located near the combustion chamber and valve seat where the temperature is high and the stress is large.

C.Can use epoxy resin bonding to repair the cracks when the temperature is not high and the stress is not high.

D.If there are many small cracks clustered together or small loopholes in the parts with little stress, can use patching method to repair them.

E.When find water blocking cover is corrosion and leakage, it is better to change all water blocking cover as new one. When replacing, pay attention to check whether there are cracks in the fold corner of the water plug cap. If there are cracks, it should not be installed.

After any of the above repairs, should check again to confirm that no leakage, then can install. If there is no repair condition and technical level, new parts should be replaced.

4.Maintenance method of screw hole slide wire of cylinder block

The reason:

The fastening bolt is too hard.

Torque is too large.

Repeated disassembly and assembly resulted in excessive wear and tear.

Improper operation during installation.

Methods of resolution:

If there is much excessive slippage or wear on screw hole of cylinder block, can be repaired by inlay method: expand the damaged screw hole appropriately, then tap out the thread according to the requirement and load the bolt with the outer thread sleeve.