Over-low engine oil pressure will lead to poor lubrication or dry friction, easily resulting in intensified abrasion of kinetic
parts within the engine or even its burnout. Generally, when the engine oil pressure is too low, the engine needs an
overhaul. Possible causes and solutions of over-low engine oil pressure are as follows:
1. Over-low oil viscosity. You shall use the engine oil with the specified viscosity.
2. Poor seal of the engine oil pump’s inlet profile or outlet profile. You shall seal up them once again.
3. Terrible abrasion of intra-pump parts. You shall replace them.
4. Clogged engine oil filter. You shall clean it.
5. Serious camshaft bearing abrasion. You shall troubleshoot the cylinder head. If necessary, replace it.
6. Serious crankshaft or connecting rod bearing abrasion, or over-wide clearance. You shall eliminate them. If necessary,
you shall reselect bearings, polish the journals or replace the crankshaft.
7. Over-low engine oil level. You shall check whether there is any leakage of the engine. After troubleshooting leakage
faults, you shall fill engine oil to reach the reference level.
1. Over-low Engine Oil Pressure
Long-time over-high engine oil pressure will lead to faults in its lubrication system. Possible reasons and treatments are as
follows:
1. Dirty engine oil. This will lead to blocked engine oil filter or bypass valve. And in this case, you shall replace the engine
oil and the filter.
2. Too small clearance of main crankshaft bearing, connecting rod bearing or camshaft bearing. You shall examine these
clearances. If so, you shall reselect the corresponding bearing or polish their journals.
3. Clogged oil passage of the cylinder block or cylinder head. You can use kerosene to clean these two oil ducts. For any
internal narrow section, you can use a thin iron wire twined by a clean duster cloth moistened by kerosene to clean them.
After doing this, you shall dry them by using compressed air.
4. Over-high engine oil viscosity. You shall change it to the engine oil with the specified viscosity.
5. Blocked pressure-limiting pressure valve of engine oil pump. Uninstall it and troubleshoot this fault.
II. Over-high Engine Oil Pressure
There are many causes of engine deterioration. Generally, engine oil quality can be determined by observing its appear-
ance and its spot.
1. If the engine oil contains a large amount of milky film, you can make the conclusion that the engine oil has been substan-
tially moisturized. In this case, its viscosity will decrease.
III.Engine Oil Deterioration
Section 3 Common Faults of Lubrication System and
Troubleshooting
III.Common Lubrication System Maintenance Data (Table 14)
141
Summary of Contents for JL481Q
Page 1: ......
Page 9: ...5 Fig 3 Components Assembly Drawing of MR479Q MR479QA Engine ...
Page 10: ...6 Fig 4 MR479Q MR479QA Engine and Its Power System ...
Page 11: ...7 Fig 5 Assembly Drawing of Engine and Its Auxiliaries MR479Q MR479QA ...
Page 12: ...8 Fig 6 Electronic Control Fuel Injection System in Engine MR479Q MR479QA ...
Page 13: ...9 Fig 7 Front view of Engine JL481Q MR481QA ...
Page 14: ...10 Fig 8 Sectional elevation of Engine JL481Q MR481QA ...
Page 15: ...11 Fig 9 Electronic Control Fuel Injection System in Engine JL481Q MR481QA ...