Pic. 3-10. Cylinder Head Details:
I - diesels «RA» and «SB»;
II - diesels «1Y», «AAZ», «12» and «AFN».
1 - cylinder head;
2 - cylinder head gasket;
3 - valve guide sleeve;
4 — a bolt of fastening of a head of cylinders;
5 - oil deflector;
6 — laying of a cover of a head of cylinders;
7 - cylinder head cover;
8 - stiffness bar;
9 - oil filler plug.
Warning. The cylinder head is not subject to grinding.
The diameter of the holes for the valve lifters is 35.0-35.02 mm.
The diameter of the bearings for the camshaft journals is 26.0-26.02 mm.
The maximum allowable flatness of the surface of the cylinder head mating with the cylinder block is 0.1 mm. The valve seats are made from powder metallurgy steel and are pressed into the cylinder head. Valve seat specifications are shown in Table 3-5. The valve guides are made of bronze and are pressed into the cylinder head from above until it stops against the collar. At the lower end of the guide bushings there is a shoulder for installing valve stem seals. Overhead valves are installed in a row vertically relative to the axis of the crankshaft and parallel to each other and are actuated directly by the camshaft cams through hydraulic tappets.
Valve specifications are shown in Table 3-6.
Note. Exhaust valves are not subject to grinding. They are only lapped.
The clearances in the valve drive mechanism are adjusted automatically by hydraulic tappets. Each intake and exhaust valve has two springs. The intake and exhaust valve springs are the same.
Spring length, mm / under load, kgf:
- internal: 18.3 / 21-23;
- external: 22.3 / 43-48.
The tappets are made of hardened steel, ground and move in the holes of the cylinder head, acting on the valves through the plungers. The cylinder head gasket is made of synthetic materials with metal trim.
Depending on the protrusion of the pistons relative to the plane of the cylinder block, gaskets of three sizes are installed. The value of each size is indicated by the corresponding number of marks applied to the gasket (tab. 3-7).
Note. If the pistons protrude by a different amount, then the thickness of the gasket is selected according to the most protruding piston.
A five-bearing camshaft is mounted on top of the cylinder head. The axial clearance of the camshaft is not more than 0.15 mm.
The gap between the necks of the shaft and the holes of the supports is not more than 0.11 mm.
The radial runout of the shaft journals is not more than 0.01 mm.
The intermediate shaft drives the oil pump and the brake booster vacuum pump. The axial clearance of the intermediate shaft is not more than 0.25 mm. Toothed belt brand and type Gates 6037 or Pirelli 135 RH 254. Change interval:
- on vehicles with engines «1Y», «RA», «SB» and «AAZ»: every 120,000 km;
- on vehicles with engine «1Z» and «AFN»: every 90,000 km.
The belt tension is checked using the VW 210 tool on the branch between the toothed pulleys of the camshaft and intermediate shaft. Belt tension is considered normal when the tool pointer moves 12-13 scale divisions.
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