The piston of the 1st cylinder is set to the position of the top dead center (TDC) of the compression stroke so that when carrying out work related to the removal of the timing chains, the installation of the gas distribution phases is not disturbed

If the valve timing is disturbed, the engine will not work normally.

Setting the TDC of the ZMZ-406 engine

Remove the oil filler cap 1.

Remove 2 spark plug caps with 3 high voltage wire seals and wires

Disconnect hose 5 and pipe 7 of crankcase ventilation from fittings on cover 6 of the head of the block

Unscrew the eight bolts 4 and remove the head cover 6 with the cover gasket.

Setting the TDC of the ZMZ-406 engine

Unscrew the four bolts 1 and remove the front cover 2 of the block head, being careful not to damage the gasket

Remove bolts 3 and remove plastic chain guide 4

Setting the TDC of the ZMZ-406 engine

Set the piston of the 1st cylinder to top dead center (TDC) of the compression stroke.

To do this, turn the crankshaft by ratchet 1 so that mark 2 on the crankshaft pulley coincides with protrusion 3 on the cover

Setting the TDC of the ZMZ-406 engine

At the same time, marks 1 on the camshaft sprockets should be located horizontally at the level of the upper plane of the block head and directed in opposite directions

After installing the piston of the 1st cylinder in the top dead center do not turn the camshafts, crankshaft and intermediate shaft.

If the marks on the gears of the crankshaft and on the gears of the camshafts do not match, then the valve timing is incorrect (the piston of the first cylinder is not set to TDC).

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After disassembling, thoroughly rinse all gearbox parts in kerosene, blow with compressed air and inspect

Possible pump malfunctions may include: leakage of the diaphragm and valves, decreased elasticity or breakage of the diaphragm spring, wear of pump drive parts