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Important Maintenance Tips For YC4108D and YC4108ZD Diesel Engine

Dec. 01, 2017

Following proper guides to maintain diesel engien can help you operate a diesel engine better. Following are some tips for Yuchai YC4108 series diesel engine, including requirements of technical maintenance, maintenance methods, de-aerate the fuel in the fuel pipe, adjusting belt tension, cleaning the inlet screen of the oil pump, cleaning the air cleaner, adding lubricating grease and scrubing the water deposit off.

I Break-In of The Diesel Engine

It is very important for new engine or an engine just after overhaul to have a 50 - hour break -in.  This break - in period can improve performance of friction pair and is essential to ensure the operating dependability and lifespan of diesel engine. If conditions permit, run the engine at speed of 1500r/min and under 25% , 50% and 750/o full load, each load an hour.

Special attentions during break - in period:


(1) Do not accelerate abruptly when the diesel engine just starts

(2) Before running engine, keep the engines idling with no load at low to medium speed for at least 5 minutes.

(3) When engine is running, do not increase load abruptly. Increase load slowly.

(4)Replace the lubricating oil when the engine runs for 50 hours. Replace the oil again after break-in period (50 hours) . Since then, oil can be replaced as required in maintenance procedures that will be mentioned afterward.

II Requirements Of Technical Maintenance

A. Daily maintenance

1. check the fuel level in the fuel tank.

2. Check the water level in the radiator

3. Check the oil level in the oil sump.

4. Check if there is coolant, oil, or fuel leakage.

5. Check the tension of the driving belt.


B. After every 50 hours

in addition to item 1 to item 5 above.

6.Check the sureness of the bolts on cylinder head.

7. Check the clearance of the intake and exhaust valves.

8. Check the injection advance angle. Adjust it if necessary.

9. Check the operating pressure of the injector and check the atomization codition.

10. Clean the inlet screen of the oil pump.


C. After every 150 hours

in addition to item 1 to item 10 above.

11. Clean the air cleaner.

12. check the electrical wiring and the contact condition of the circuit joints.

13. Add calcium- sodium base grease on the water pump bearings.

14. Check the torque of main bolts and nuts.

15.  Please remove the scale in the water deposit.

16. Replace the lubricating oil.


Attention :

1. When the engine runs for 1200 ~ 1500 hours, take apart the sump, disassemble the main bearing shells, thrust plate, connecting rod bearing shells, crankshaft bearing shells and check their wear conditions.


Replace the one that wears out and clean the oil sump at the same time. Then assemble them altogether.


2. If anymore or more is replaced, such as crankshaft, piston, piston ring, cylinder connecting rod, connecting rod bearing shell, main bearing thrust plate, camshaft, camshaft bushing, tappet cylinder block etc. , diesel engine can run properly only after the break-in period Engine cannot run with heavy load and at high speed just after replacement lest the components be destroyed and engine lifespan

3. When engine is used under clean ambient condition, the maintenance period can be observed as detailed in the diagram shown before. But if the ambient condition is harsh and there is heavy dust, reduce the maintenance period of the air cleaner according to specific case.

III. Maintenance Methods

1. Check and replace the lubricating oil

Check and replace the lubricating oil

Check and replace the lubricating oil

Always check the oil level in the oil sump: There is an oil gauge at the left side of the cylinder block (look from the side of flywheel). before checking the oil level, bring out the oil gauge and wipe it dry. Then, put the gauge in and bring it out again to check the oil level. The level should be within the upper and lower limits of the oil gauge ( as shown in Figure). If the level is not enough, add some oil, as required, from the cylinder head cover. Total oil volume in the oil tank is about 13L, and the oil volume in the oil sump is about 11L. At the bottom of the oil sump, there is an oil passage screw plug, which can be used when we need to replace the oil. Replacing oil should he done just after stopping engine. At this time, foreign matters and oil are mixed and can be replaced together. Waste lubricating oil should be collected after being replaced in order to prevent polluting environment.

2. De-aerate The Fuel In The Fuel Pipe

De-aerate the fuel in the fuel pipe

De-aerate the fuel in the fuel pipe


Outside the fuel injection pump, there is a fuel supply pump, which is equipped with a hand priming pump. The hand priming pump can be used to de-aerate the fuel in the fuel pipe. When using the hand priming and again handle cap and it will rise up. Push the cap down again and again, the fuel can be pumped from the fuel tank to each fuel passage and the fuel chamber. At the same time, loosen the air outlet screw plug and expel the air out. After using the hand priming pump, revolve back the handle cap in case that the air go into the fuel supply system.

3. Check And Adjust The Belt Tension

3.Check And Adjust The Belt Tension

 Check And Adjust The Belt Tension

Driving belt must be properly tensioned. Inspect the driving belt deflection by pushing on the belt with a force of about 4-5kg midway between pulleys. If the belt deflects about 10 ~ 15 mm, the tension is just as required. If the belt tension is too loose or too tight, adjust the tension by relocating the position of the generator.

4. Discharge The Coolant

Discharge The Coolant

Discharge The Coolant

There is water drain valve on the case of the oil cooler at the left side of the cylinder block (look from the side of the flywheel), It is used to drain coolant in the water jacket of the diesel engine. After drain the water coolant, close the valve.

5. Clean The Inlet Screen Of The Oil Pump

inlet screen filter of thee fuel pump

inlet screen filter of thee fuel pump

There is an oil pump outside the fuel injection pump. At the joint of the fuel inlet of the fuel supply pump, there is a filter screen, which is used to filter contaminants. It needs cleaning timely. When cleaning, screw down the hinged screw on the fuel control lever, take out the filter screen and clean the screen with fresh diesel fuel. After cleaning, install back the screw.

6. Clean The Air Cleaner

Clean The Air Cleaner

Clean The Air Cleaner

Do timely maintenance to the air cleaner as required. During maintenance, take out the air cleaner element, brush dust off the surface of the element and then, blow it inside out with compressed air of 0. 4-0.6 MPa (4 ~6kg/cm2). Check the element, the filter paper and the sealing ring.to see if there is damage. If there is, replace it. At the same time, clean the dust off the dust off the dust chamber. Watch out that the filter paper cannot be cleaned with fuel, water, or other liquids. Under harsh condition, reduce the maintenance period of the air cleaner according to actual facts.

7. Add Lubricating Grease

adding of the lubricating grease.jpg

adding of the lubricating grease

Bearing in the water pump should be lubricated with calcium sodium base grease. Add lubricating grease in time, as required, to prevent damage. There is a .up for adding lubricating grease on a part of water pump. When adding grease, point the oil gun into the cup and shoot the grease into the bearings.

8. Scrub the water deposit off

Scrub the water jacket the coolant tank wall and the water jacket with cleaning liquid in time, in order to ensure cooling effectiveness and avoid overheating of the diesel engine.

Generally, the cleaning liquid is appropriated as follows: add 750 ~800g sodium hydroxide and 150g kerosene per l0 - liter water and mix the three evenly.


Cleaning procedures: Drain the water coolant in the water tank and add the cleaning liquid into the tank. Run the diesel engine with cleaning liquid as coolant water in medium speed about 10-15 minutes, warning up cleaning liquid. Let the cleaning liquid remain in the tank for about 12-15 hours and run the engine again in medium speed about 10-15 minutes. Then, run the engine in medium speed for some time and drain the water. At this time, the cleaning is completed. If the water deposit is serious, repeat the procedure aforementioned 2-3 times.

Note: Sodium hydroxide is strongly basic. Do not eat or touch it. If your skin contacts it, please rinse you skin immediately with water.

For more user manual details, please visit:

Diesel Engine Generator Adjustment

Diesel Engine Operation


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