Camshaft and valve train of a 4-cylinder petrol engine
1. Main bearing caps; 2. Nut, 20 Nm; 3. Key (working without tightening); 4. Camshaft; 5. Cone valve crackers; 6. Outer and inner valve springs; 7. Valve guide. Repair version with flange; 8. Cylinder head; 9. Sealing ring; 10. Valve guides; 11. Valves; 12. Plug; 13. Plug; 14. Lower valve spring plate; 15. Oil seal; 16. Upper valve spring plate. Designation: wide chamfer outside, chamfer inside; 17. Hydraulic disc pusher
4-cylinder petrol engine
Removal
1. Remove the upper timing belt cover.
2. Remove the cylinder head cover.
3. Set the crankshaft to TDC for cylinder 1 (see subsection 2.5.2).
Attention! Do not change the position of the engine crankshaft any further.
4. Loosen the timing belt and remove it from the camshaft gear from above (see subsection 2.5.1.1).
5. Wedge the camshaft from the front with a tenon. To do this, insert a suitable tenon or a strong screwdriver into the hole in the camshaft gear and rest it against the upper edge of the cylinder head. To avoid damaging the sealing surface of the cylinder head, place a wooden lining underneath. Holding the screwdriver firmly, loosen the camshaft mounting bolt. Unscrew and remove the camshaft gear; if necessary, tap it in with light blows of a rubber hammer. Remove the key from the camshaft.
6. Mark all main bearing caps. Mark four caps, from right to left, looking in the direction of travel, with numbers from 1 to 4.
7. Remove covers 1 and 3. Then unscrew covers 2 and 4 alternately in a crosswise manner.
8. Remove the camshaft.
Caution! If the plate tappets are removed, they must be marked so that they can be reinstalled in their original positions. Place the plate tappets with the sliding surface facing (shifting towards the camshaft) down.
Installation
1. If necessary, the camshaft runout can be checked at the factory before installation. Wear limit: 0.01 mm.
2. If the same camshaft is to be installed again on an engine with high mileage or noise in the valve drive, it is recommended to check the axial clearance. Wear limit: 0.15 mm. The measurement is carried out with the plate tappets removed and the first and last main bearing caps installed.
3. Install a new camshaft sealing ring. Pre-lubricate the lips and outer edge of the sealing ring with oil.
4. Perform a test installation of the bearing caps, paying attention to the position of the centers. The caps must be installed so that the holes in the caps and the cylinder head match. Pay attention to the marks.
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5. If the plate tappets were removed, install them in their original places. Lubricate the plate tappets with a thin layer of oil and do not tilt them when installing.
Attention! The plate tappets cannot be interchanged!
6. Lubricate and install the camshaft.
Attention! The cams of cylinder 1 must be directed upwards. Install the bearing caps according to the marks. Pay attention to the position of the centers.
7. Tighten covers 2 and 4 crosswise to 20 Nm.
8. Install covers 1 and 3 and tighten to 20 Nm.
9. Install the camshaft key. Install the drive gear and tighten to 80 Nm, holding the gear with a tenon.
10. Place the timing belt on the camshaft timing gear, paying attention to the correct position of the intermediate shaft and vibration damper (see subsection 2.5.2).
11. Tighten the timing belt (see subsection 2.5.1.1).
12. Install a new cylinder head cover gasket, carefully tightening the cover bolts to 10 Nm.
13. Install the timing belt guard.
Attention! If new plate tappets are installed, the engine must not be started for approximately 30 minutes, otherwise the valves will rest against the pistons!
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