The forklift truck engine overhaul cycle can be said to be a cycle time that is not expressly stipulated. It is judged by the forklift driver or equipment manager observing the operation performance of the forklift truck. You can refer to the following points to determine whether an overhaul is needed: The mast shakes , The stability of the forklift is reduced, and the vulnerable parts of the forklift systems are approaching or reaching the end of their life. For example, the forklift has abnormal noises during operation (such as the mast, drive axle, steering axle, internal engine, etc.); poor brakes, abnormal noise of the forklift motor Need to replace the motor bearings, heavy steering or unstable steering of the steering system, large gaps in the connecting parts of the forklift, and worn out appearance of the car body.

The following forklift truck engine overhaul content is mainly divided into four parts:

1. Disassemble the engine.

2. Clean the parts.

3. Check the wear and tear.

4. Assemble the engine.

   1. How to disassemble and wash forklift truck engine
   First remove the engine from the forklift, and it must be done in a state where the engine is completely cooled, otherwise it will cause deformation of some parts.
   A. Water is discharged from the engine cooling system, and engine oil and hydraulic oil are discharged from the engine and hydraulic transmission.
  B. Remove the safety shed and seat, remove the radiator cover, and remove the exhaust pipe muffler.
  C. Remove the foot pedal, remove the radiator, exhaust pipe and its accessories.
  D. Disassemble the connecting parts (hoses, ducts, etc.) of the engine and hydraulic transmission and other systems.
  E. Decompose the connection between the engine and the main drive (universal joints, etc.).
  F. Hang the engine on the lifting equipment, and unscrew the plug bolts connected with the frame.
  G. Lift the engine with lifting equipment and place the engine on the bench.
   2. How to disassemble the engine
  A. Remove the cylinder head and gasket. When removing the cylinder head, do not use a screwdriver or other sharp tools to avoid damage to the cylinder head gasket.
  B. Remove the clutch from the engine. Before removing the clutch, check whether there are marks on the clutch cover and the flywheel. If not, mark them, and then remove the clutch fixing bolts.
  C. Remove the oil pan, gasket, oil pipe and oil pump.
  D. Remove the valve. All valves are marked to prevent the position from being reversed, and the valve seat is also marked on the cylinder head.
a. Check whether there is a mark on the top of the valve. If there is no mark, mark the top of the valve with a steel head in order (marking must be done when the valve is closed. It is not allowed to use a file as a mark on the edge of the valve top or on the valve stem. );
  b. Press down the spring baffle plate and spring, and use needle-nose pliers to remove the lock pin;
  c. Take out the valve, valve spring and spring pad.
   E. Remove the piston connecting rod assembly. Each piston connecting rod group should be disassembled separately. To ensure correct installation, the big end and cover of the connecting rod should be marked with the cylinder number, and the sequence of numbers should be by the front end of the engine water pump.
  a. Remove the connecting rod nut, remove the connecting rod end cap, gasket and bearing, and separate them in order.
  b. Push the connecting rod upward to separate the connecting rod from the journal. Push out the piston connecting rod assembly (if the cylinder mouth is ground into a step, it should be flattened first) to avoid damaging the piston ring.
  c. After the piston connecting rod is taken out, the connecting rod, cover, gasket, bolts and nuts should be installed back as they are to prevent confusion.
  F. Remove the starting claw and the crankshaft pulley, and then pull out the crankshaft pulley hub with a push-pull device.
  G. Remove the cover, box and timing gear of the distribution conveyor. When removing the timing gear, first check whether there is a mark on the timing gear. If there is no mark, put corresponding marks on the two gears (when the first cylinder is at the top dead center position).
   H. Remove the oil pump, oil pipe, valve lifter, distributor connecting shaft, and pull out the camshaft.
  I. Remove the crankshaft. Check whether there are marks on the bearing caps. If there are no marks, mark them in order. Remove the fixing bolts and lift off the crankshaft. Then put the bearing cap and gasket back in place, and tighten the fixing bolt a little.
  J. Unscrew the flywheel fixing bolts, and remove the flywheel from the flange of the crankshaft.
  K. Remove the oil seal at the rear end of the crankshaft and the flywheel housing.
  L. Decompose the oil plug connecting rod group.
  a. Remove the piston ring from the piston.
  b. Remove the piston pin and place it in the order of the marks on the top of the piston.
Drain the oil first, and then disassemble the valve cover and rocker arm from top to bottom. The big pump, the cylinder head, the timing gear flywheel, the flywheel housing, then open the oil bottom, unload the oil pump, first unload the small tile and make a mark to poke the piston, and then unload the large tile to make a mark. The crankshaft, remove the eccentric shaft, and poke out the cylinder liner, basically even if it is completely disassembled.
   Three, cleaning parts
  1. Use a brush to soak in diesel oil or detergent to clean the dismantled parts.
  2. Scrape out the sealant at each bonding point cleanly.
  3. Drain the cleaned parts and arrange them separately.
   Four, check the wear
   1. First look at the color and quality of the oil, whether there are iron filings on the surface, and look at the viscosity of the oil. For example, there are a lot of iron filings in the engine oil, indicating that the crankshaft or connecting rod bushes need to be ground, or even the crankshaft is worn. If the machine is very viscous, it means that the oil has not been changed for a long time.
2. When disassembling the crankshaft of the connecting rod piston, observe the conditions of the connecting rod bearing and crankshaft bearing. If it is found that the entire connecting rod cannot be used after being ground, if the crankshaft is not severely ground, it can be used after grinding the shaft. .
  3. Observe the wear of the cylinder liner, and pay attention not to hit the body of the engine when the cylinder liner is disassembled to prevent damage.
  Five. Assemble the engine
  When installing forklift engines, generally follow the order from inside to outside, from bottom to top, from back to front, from left to right (that is, the reverse order of removal)
   1. The crankshaft, the surface of the crankshaft bush, the connecting rod, the piston, the piston, and the camshaft should be painted with engine oil during installation, and they should not collide.
  2. When installing the camshaft and high-pressure fuel injection pump gear, pay attention to the alignment of the first cylinder mark on the gear.
  3. When installing the piston ring, it is necessary to use a dedicated worker to install from the third ring to the first one. The piston ring is used in a complete set and cannot be damaged at will.
  4. The opening of each ring should be staggered by one hundred and twenty degrees, and it should not be in the vertical and horizontal directions.
  5. When installing the cylinder liner, apply butter on the O-ring. Do not directly knock the cylinder liner with iron.
  6. Always use special tools when installing the piston and connecting rod, and install it in the original direction of the piston. It is not allowed to directly hit the piston with iron, and apply oil on the connecting rod bush (contact surface with the crankshaft).
   7. Install engine oil on both sides of the cylinder head gasket.
8. When installing the cylinder head screws, use a kilogram wrench to tighten them in two to three steps from the middle to the four sides. The force of the first screw is 250 to 300 N, and each screw has the same force. When tightening the crankshaft bearing connecting rod bearing, tighten it in two to three times from the middle to the two ends.
 Six. The details of the parts that need to be replaced and overhauled for forklift truck engine overhaul are as follows:
1. Replace the following accessories: cylinder liner, main bearing bush, connecting rod bearing bush, thrust plate, intake and exhaust valve, valve guide, push rod, tappet, camshaft bushing, bearing, cylinder head gasket, full car paper gasket, Oil seals, machine filter elements, air filter elements, oil filter elements, transmission belts, glow plugs, spark plugs, spark plugs, flywheel rings, friction discs, and all vulnerable parts and damaged accessories.
  2. Repair the following parts: oil passage, water passage, radiator, starter, generator, pressure plate, large pump, fuel injector, crankshaft, carburetor, valve seat ring.
   3. There is no leakage, and the power reaches the factory performance.