Opel Corsa B, Combo, Tigra

Since 1993-2000 of release

Repair and car operation

Procedures of repair of petrol engines SOHC without their extraction from the car

Reduction of the piston of the first cylinder in position of the top dead point of a step of compression (ВМТ)

The general information

As the top dead point (ВМТ) is called the highest point of a piston stroke in the cylinder. Strictly speaking, in 4-taktnyh engines in the course of rotation of a cranked shaft the given position is reached by each of pistons twice: once in the end of a step of compression and the second - in the end of a final step. At performance of options of phases газораспределения and installation of a corner of an advancing of ignition in overwhelming majority of cases position ВМТ of the end of a step of compression of the piston (usually the first cylinder) is used.

Necessity for reduction of the piston (it) in position ВМТ arises at carrying out of many procedures, in particular such, as removal/installation of camshafts, components of drive ГРМ and the ignition distributor.

Some engines are designed in such a manner that at проворачивании cranked or distributive (ых) shaft at removed газораспределительном a belt there can be an input of valves in contact with the bottoms of pistons that is fraught with risk of damage of corresponding internal components, up to destruction of moulding of a head of cylinders.

Do not suppose change of position of shaft after belt removal!

Order of performance of procedure

PERFORMANCE ORDER

Reduction of any of pistons in position ВМТ is made by проворачивания a cranked shaft of the engine. If to take a detached view of the engine of drive ГРМ, the direction clockwise will be a normal direction of rotation of a cranked shaft. Remember that attempt проворачивания a shaft counter-clockwise can lead to infringement of adjustments of phases газораспределения. The first is the extreme cylinder from outside drive ГРМ. Disconnect a negative wire of the accumulator. For the purpose of simplification проворачивания the engine turn out all spark plugs. For the purpose of providing of access to label ВМТ on a camshaft cogwheel, remove the top cover of drive ГРМ (see Has undressed Removal and installation of a cover of drive ГРМ). Turn a cranked shaft in an hour hand direction so that the cams of a camshaft operating valves of the first cylinder have been turned by the made narrower part upwards. To turn a cranked shaft it is possible rotating a forward wheel by established 5th transfer, or rotating a cranked shaft for the central bolt of fastening of its pulley at neutral position РКПП or АТ and the cocked lay brake. Do not turn the engine for a bolt of fastening of a cogwheel of a camshaft since thus it is possible to load a gear belt excessively. Combine a label on a cogwheel of a camshaft with label ВМТ on a cover of a gear belt. Thus the label on a pulley of a cranked shaft (engine C14NZ) should coincide with a label on the bottom cover of a gear belt. On engines X12SZ and C14SE the label is on a cogwheel of a cranked shaft. Thus the piston of the first cylinder is in position ВМТ. Adjusting labels ВМТ of engine C14NZ Adjusting labels ВМТ of engines X12SZ and C14SE