Contents: Cylinder head ↓ Valve seats ↓ Valve guide bushings ↓ Valves ↓ Clearances in the valve drive…↓ Valve springs ↓ Pushers ↓
The four-stroke, five-cylinder, in-line, liquid-cooled petrol engine is located along the longitudinal axis of the vehicle with an inclination to the right. The engine uses a valve timing mechanism with an overhead camshaft driven by a toothed belt. The valves are actuated directly by the camshaft cams through tappets (wN engine and JS engine up to 1986 model year) or through hydraulic tappets (jS engine since 1986 model year).
Main technical characteristics of five-cylinder engines
Cylinder head
The cylinder head is cast from aluminum alloy. The valve seats and guide bushings are pressed into the cylinder head. There are no special markings on the cylinder head gasket for orientation. The gasket should be installed with the marks facing the cylinder head plane.
Warpage of the mating plane of the head with the cylinder block, no more than, mm: 0.1.
Permissible height of the cylinder head after grinding, not less than, mm: 132.7 5.
Valve seats
Valve seats are non-removable. If there are traces of burning or wear that cannot be removed by grinding, replace the cylinder head.
Valve seat characteristics
(The information is posted on this website: VWMANUAL.ru)
Valve guide bushings
The valve guides are made of special brass and pressed into the cylinder head.
Maximum permissible marginal clearance (when worn out) between the valve stem and the guide bushing (for measurement methods see page.), mm:
- for intake valves: 1.0;
- for exhaust valves: 1.3.
Valve guide bore diameter, mm: 8.013-8.035.
Valves
The valves are arranged in a row in the cylinder head and are actuated directly by the camshaft cams via tappets. The exhaust valves are not subject to grinding.
Valve characteristics
Clearances in the valve drive mechanism
WN engine and JS engine up to 1986 model year
The clearance between the camshaft cams and the adjusting washers at a coolant temperature above 35°C should be 0.25±0.05 mm for the intake valves and 0.45±0.05 mm for the exhaust valves; on a cold engine, 0.20±0.05 and 0.40±0.05 mm, respectively.
The clearance is adjusted by selecting the thickness of the adjusting washers installed on the upper ends of the tappets. Adjusting washers with a thickness of 3.00 to 4.25 mm with an interval of every 0.05 mm are supplied as spare parts.
JS engine since 1986 model year
Clearances in the valve drive mechanism are compensated automatically by hydraulic tappets.
Valve springs
Each intake and exhaust valve has two springs. The springs are the same for both intake and exhaust valves.
Pushers
The valve tappets are located directly in the cylinder head. Adjusting washers of different thickness are installed on the upper ends of the tappets to adjust the thermal clearances of the valves.
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