Disassembly
1 - main bearing cap screw
2 - main bearing caps
3 - upper starting half washers
4 - upper shells of main bearings
5 - crankshaft
6 - lower shells of main bearings
7 - lower thrust washers
8 - screw, 10 Nm
9 - intermediate shaft
10 - oil sealing ring
11 - screw, 25 Nm
12 - flange for intermediate shaft
13 - oil sealing ring
14 - screw, 20 Nm
15 - O-ring front flange
16 - seal
17 - lower bearing shell
18 - upper bearing shell
Before starting work, thoroughly clean the entire outer surface of the engine. Close all engine openings with a clean cloth beforehand so that foreign objects cannot get inside.
Engine disassembly is detailed below. Therefore, we describe the work that is carried out either with the assembled or disassembled engine, without repeating the specific disassembly operations.
If you want to completely disassemble the engine, you only need to combine the individual operations with each other, and in the specified sequence.
Usually, when disassembling, one should think that before dismantling, the position of all moving or sliding parts should be noted, so that they can then be reinstalled in their original position in case they are used again. This is especially important for pistons, valves. bearing caps and bearing shells.
Don't mix up the details. The valves can be stuck into the bottom of an upside-down cardboard box so that they can be numbered.
On the surfaces of bearings and seals, in no case should any marks be made with a scriber or even with a digital stamp. Many parts are made of aluminum and should be handled accordingly. If some parts can be separated only by tapping on them, use only a rubber, plastic or leather mallet.
In case you do not have a mounting diagram according to the instructions, it is best to cut out suitable wooden parts on which to put the engine in such a way that you can access the top and bottom sides of the engine. After dismantling, the cylinder head can be clamped in a vice together with a metal bracket into which the suction channel studs are screwed.
The following is a typical disassembly of the engine.
Dismantle all minor parts of the engine, i.e. ignition distributor, carburetor together with suction duct, exhaust duct, injection unit parts, etc.
Unscrew the belt guard and remove it.
Remove the belt tensioner from the end of the engine.
Unscrew the crankshaft pulley from the shaft along with the flywheel.
Unscrew the water pump.
Unscrew the oil filters. Unscrew the oil cooler. placed between the oil filter and the filter base (disconnect the nut).
If necessary, unscrew the base from the motor.
Take out the oil gauge.
Unscrew the cylinder head cover and immediately remove the seal.
Remove the cylinder head.
Turn the engine over and unscrew the oil bath. Remove the seal.
Unscrew the oil pump from the underside of the crankcase and remove it.
Paint the cylinder numbers on the connecting rod bearing caps and remove the bearing caps one by one. The two connecting rod bearings must always be at bottom dead center when caps are removed. Pull the connecting rods alternately together with the pistons upwards from the cylinder bores. Please note that bearing caps and shells are immediately screwed back onto the respective connecting rods. The connecting rod bearings are fastened with malleable screws; screws cannot be reused.
Remove the crankshaft. In this case, designate the bearing caps with numbers (No. 1 on the side of the belt pulley, No. 5 - on the flywheel side).
Remove the intermediate shaft flywheel.
Unscrew the intermediate shaft flange and press out the flange. Remove the shaft from the engine.
Assembly
When carrying out any operation to assemble the engine, the following provisions must be observed.
Check for foreign bodies before assembling.
Apply a film of oil to all rotating or sliding parts. Carry out this operation before starting assembly, because otherwise the oil cannot get on the bearing surfaces themselves, it is especially important to generously lubricate the pistons, piston rings and cylinder walls with engine oil before starting the assembly.
Thoroughly clean all parts of the cylinder block if the engine is completely disassembled. When partially disassembling the engine, make sure that no foreign object can get into the disassembled parts of the engine or its cavity. All openings are either sealed or plugged with rags.
Lubrication channels and holes are best blown out with compressed air. If this is not possible, push through the channels or holes with some suitable wooden object (never metallic).
Always replace O-rings, seals, etc. You can not save on such parts and use previously damaged parts.
The table of dimensions and adjustment parameters shows the wear limits of most moving parts. If any part is in doubt or if it has almost reached the wear limit, it is better to replace the part in order to avoid a new disassembly of the mechanism in the near future.
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