Removing
1. Remove the timing belt (see Removing and installing timing belt). Before loosening the timing belt, move the engine off TDC by turning the crankshaft 60°counterclockwise to equalize the distribution of forces developed by the valve springs and prevent the camshafts from turning, fraught with damage to the internal components of the mechanism as a result of the introduction of the pistons into contact with the valves.
![](https://www.opelbook.ru/img/astra/3505.jpg)
2. Remove the camshaft gears (see Removal and installation of gear wheels crankshaft / camshafts and intermediate rollers).
3. Start at the intake camshaft: spiraling from the edges inwards (in the reverse order shown in illustration 26.15), in several steps, half a turn per approach, evenly loosen the bolts securing the shaft support covers (the force developed by the valve springs with this approach will also be weakened evenly and gradually). Once the action of the springs has been neutralized, unscrew the bolts by hand and remove the covers - try not to let the guide bushings of the covers fall out (if any).
A - The order of tightening the fasteners of the covers of the exhaust camshaft supports (for the intake shaft the order is the same)
B - Numbering order of the camshaft bearing caps
C - Identification marking must be clearly visible both on the caps and on the surface of the head
A.
![](https://www.opelbook.ru/img/astra/3506.jpg)
B.
![](https://www.opelbook.ru/img/astra/3507.jpg)
C.
![](https://www.opelbook.ru/img/astra/3508.jpg)
Support bearing caps are numbered in order from 1 to 5 (intake shaft) and 6 to 10 (exhaust shaft) and during assembly must be installed strictly in their original places. Be careful not to lose the guide bushings of the covers (where installed).
Failure to be careful when loosening the support bearing caps may result in mechanical damage, which will lead to the need to replace the cylinder head. Loosen the caps carelessly, they can be broken. If at least one cover is broken, you will have to change the entire head of the block - in the manufacture of covers, they are processed together with the head and are not individually supplied to the spare parts market.
4. Raise the camshaft and remove it from the engine, carefully remove the oil seal.
5. Acting in a similar manner, remove the final camshaft.
6. Prepare 16 small clear plastic bags or clean plastic cups and label them according to the number of valves. Using a rubber suction cup, remove the pushers from the head and place them in their respective cups.
![](https://www.opelbook.ru/img/astra/3509.jpg)
To prevent oil from leaking out of the hydraulic lifters, place the tappets with their working ends up.
Examination
1. Carefully examine the condition of the bearing journals and camshaft cams. Replace shaft if scored or scratched. Also check the condition of the working surfaces of the plain bearings in the bearings of the gas distribution mechanism housing; in case of defects that cannot be eliminated, it will be necessary to replace the cylinder head (see above Withdrawal).
2. Alternately laying the camshafts in prisms, using a plunger-type dial gauge, determine the amount of their radial runout (on bearing journals). When the measurement results are out of range (see Specifications) the camshaft must be replaced.
3. Check up a condition of pushers and their landing sockets in a head. If there are signs of excessive wear of the working surfaces, cracks, scoring and other damage, replace the pushers.
The pushers must also be replaced if the operation of the valve mechanism has recently been accompanied by an increased background noise.
Installation
1. Lubricate the tappets with clean engine oil and carefully place them in their seats in the cylinder head.
![](https://www.opelbook.ru/img/astra/3510.jpg)
C3 - Intake shaft
T3 - Exhaust shaft
2. After lubricating with molybdenum-containing grease, lay the camshafts in their beds.
On 1.8 liter engines, the intake shaft is marked C3, the exhaust shaft is T3. Make sure the crankshaft is still turned at 60°BTDC and rotate the camshafts so that the cams of the first cylinder are turned with the lobes up. Temporarily seat the gear wheels on the shaft journals and make sure that the TDC alignment marks are correctly aligned with the mating marks on the head (see Bringing the piston of the first cylinder to the position of the top dead center of the compression stroke (TDC).
3. Make sure that the mating surfaces of the bearing caps and cylinder head are absolutely clean and dry. Lubricate the necks and cams of the shafts with clean engine oil.
4. Apply a layer of sealant to the mating surfaces of the end caps and block head on both sides of the gland seats.
![](https://www.opelbook.ru/img/astra/3511.jpg)
5. If equipped, make sure the guide bushings are in place, then install the covers.
The covers are numbered in ascending order from front to rear, in addition, the corresponding numbering is applied to the upper plane of the head - the marking should be read when looking at the engine from the front.
6. Tighten the bolts of the intake shaft covers, first by hand, then, moving in a spiral from the center outward, in several steps, half a turn per approach evenly (in order to ensure gradual and uniform squeezing of the valve springs) pull them until the covers are pressed against the head. Next, in the same order, tighten the fasteners with the required force.
![](https://www.opelbook.ru/img/astra/3512.jpg)
Failure to tighten fasteners in the correct order may result in damage to the covers and the need to replace the cylinder head (see above Removal).
7. Proceeding in a similar manner, tighten the fasteners of the exhaust shaft support bearing caps.
8. Install new oil seals (see Replacing camshaft seals).
9. Install the camshaft gears (see Removal and installation of gear wheels crankshaft / camshafts and intermediate rollers).
10. Achieve the correct alignment of the TDC timing marks of the crankshaft and camshafts, then reinstall the timing belt (see Removing and installing timing belt).
11. Install the timing cover and timing cover (see Removal and installation of a cover of the gas-distributing mechanism and Removing and installing timing cover).
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