The piston of the 1st cylinder is set to the top dead center (TDC) position 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 top dead center of the first cylinder of the engine ZMZ-405, ZMZ-406

Remove the oil filler cap 1.

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

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

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

Setting the top dead center of the first cylinder of the engine ZMZ-405, ZMZ-406

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 guide 4 for the chain.

Setting the top dead center of the first cylinder of the engine ZMZ-405, ZMZ-406

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 top dead center of the first cylinder of the engine ZMZ-405, ZMZ-406

In this case, 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).