On vehicles with fuel injection, disconnect the air supply hose from the throttle body or central injection unit. Remove air filter. Disconnect the electrical wires from the carburetor and disconnect the carburetor plug connectors. Disconnect the electrical wiring from the components and sensors of the fuel injection system. Disconnect the throttle cable and vacuum hoses from the carburetor and remove the carburetor. Remove intake pipe. Unbolt muffler exhaust pipe flange from exhaust manifold. Remove exhaust manifold. Disconnect the high voltage wire harness and remove the spark plugs. Disconnect the cooling hoses from the cylinder head to the radiator and heater. Remove cylinder head cover. Loosen the cylinder head bolts. Remove cylinder head. Clean the removed parts and visually determine their condition. When cleaning the mating surfaces of the cylinder head, use special detergents. It is forbidden to use objects that can leave scratches and abrasive materials for this purpose.
Replace the gaskets every time the cylinder head is removed.
When installing the cylinder head, install a new cylinder head gasket with the mark «Oben» («Top») towards the plane of the head. Insert bolts 8 and 10 into the holes of the cylinder head (pic 2-21) or install dowel pins in the holes for these bolts in the cylinder block. then install the cylinder head. Install new washers and cylinder head bolts.
Gradually tighten the cylinder head bolts in the order shown (pic. 2-21) and tightening torques. The tightening of the cylinder head bolts is done very carefully. Before tightening, check the accuracy of the torque wrench. Tighten the bolts on a cold engine in three stages:
- 1st reception: moment 4 kgf·m;
- 2nd reception: moment 6 kgf·m;
- 3rd trick - turn 180°with a hard wrench without stopping. Tightening in two steps of 90°is allowed.
Warning. Additional tightening of the cylinder head bolts, on a warm engine, as part of maintenance or after repair on gasoline engines is not allowed.
Install the camshaft drive belt as shown below. Install the toothed belt guards. Install the alternator and coolant pump drive belt, tension bar and adjust the belt tension.
Install the exhaust manifold and muffler exhaust pipe flange. Reinstall intake manifold and carburetor. Connect the cooling and heating hoses to the cylinder head. Install the cylinder head cover. Attach vacuum hoses to the carburetor, connect plug connectors, electrical wires and carburetor control cables. Connect electrical connectors and pipelines to the fuel injection system. Install the air filter, spark plugs and high voltage wires. Fill the engine cooling system with coolant. Connect the wire to the negative terminal of the battery. Start the engine, listen to its operation and, if necessary, adjust the ignition timing, engine idling.
Dismantling, assembling, checking the technical condition and repair of the cylinder head
Remove the cylinder head as above and place it on a stand. When disassembling the cylinder head, put marks on the removed parts in order to put them in their original places during assembly. Remove spark plugs.
Remove the bearing caps No. 5, 1 and 3 of the camshaft, then unscrew the nuts of the studs securing the bearing caps No. 2 and 4 alternately crosswise.
Remove the camshaft from the cylinder head bearings and remove the valve lifters. Install a device for compressing valve springs or a special device VW 541 for removing and installing valve cotters on the cylinder head and, using pliers with pointed ends, release the valves from crackers, after pressing the lever of the special device (pic. 2-22 and 2-23). Remove valve springs with poppets. Remove valve stem seals and spring washers using pliers. Take out the valves. Retrieve the position of the removed parts in order to put the parts that cannot be replaced during assembly in their original position. Clear details. Check the degree of wear of the valve guide sockets and the clearance between the valve bushings and the valve stems. so that the end of the valve stem is flush with the edge of the guide bush, and determine the gap between the end of the stem and the edge of the guide bush using tool VW 387 with an indicator. Replace the guide bushings if the indicator reading is greater than 1 mm for the intake valve bushings and 1.3 mm for the exhaust valve bushings. Check whether the flatness of the mating surface of the cylinder head is broken. using a straightedge and feeler gauges. Grind, if necessary, the mating surface of the cylinder head within acceptable limits. Check the condition of the valves and valve springs.
Check the condition of the valve seats and grind them if necessary. Grinding is carried out with a special tool and within acceptable limits.
In the case of grinding valve seats, to ensure the normal operation of hydraulic valve tappets, it is necessary to maintain a minimum distance «A» (pic. 2-24 and 2-25) between the end of the valve stem and the upper plane of the cylinder head, which for intake valves should be 33.80 mm. for exhaust valves - 34.10 mm.
Pic. 2-24. Dimensions for grinding valve seats:
Vp. - inlet valve seat
Issue. - exhaust valve seat;
Р — the plane of a head of cylinders;
a - outer diameter of the working chamfer of the exhaust valve seat;
b is the distance from the end of the working chamfer of the intake valve seat to the plane of the cylinder head;
c - width of the working chamfer of the exhaust valve seat;
d is the outer diameter of the working chamfer of the inlet valve seat;
e is the distance from the end face of the working chamfer of the intake valve to the plane of the cylinder head;
f is the width of the working chamfer of the inlet valve seat.
The shrinkage of the working chamfer of the valve seat must not exceed a value equal to the difference between the value «A» before grinding the valve seat and the minimum value «A» after grinding.
Grind, if necessary, the working chamfers of the inlet valves The working chamfers of the exhaust valves are not subject to grinding, grinding of the exhaust valves is allowed, in other cases they must be replaced.
Before assembly, thoroughly clean the cylinder head. as well as after grinding the valve seats and lapping the valves. Check the degree of wear of the camshaft, the maximum radial runout of the middle journal of the shaft and its axial movement, which must be within acceptable limits.
Insert valves into guide bushings. lubricate the valve stems with engine oil.
The technical condition of the hydraulic pushers is checked while the engine is running, because their design is non-separable and cannot be repaired. To check, start the engine and leave it running until the first activation of the electric fan of the cooling system.
Maintain the engine speed of 2500 rpm for 2 minutes.
If noise is heard in the valve train, determine the faulty tappet as follows:
- remove the cylinder head cover;
- turn the engine crankshaft clockwise by the pulley mounting bolt so. so that the backs of the camshaft cams corresponding to the valves of the cylinder being checked are facing the hydraulic tappet;
- drown the pusher with a wooden or plastic wedge and measure the free play of the pusher, which should not exceed 0.10 mm before the valve opens. If it is larger, the pusher must be replaced.
Warning. After installing a new pusher., pre-filled with oil and pumped, it is allowed to start the engine no earlier than 30 minutes in order to prevent the valves from hitting the pistons.
When reassembling the cylinder head, reinstall the valve spring washers and insert the valves into the guide bushings. Using mandrel 10 204, press new valve stem seals onto the valve guides, after putting protective caps on the valve stems. Install the valve spring washers. Install springs and spring plates. Install the cotters with the valve spring compressor. Insert the valve lifters into the head holes, after lubricating them with engine oil to facilitate installation. Pay special attention to that. so that the pushers are put in their original position. Lubricate the bearing journals and camshaft cams with engine oil and place it in the cylinder head bearings so that the cams of the first cylinder point upwards. Install bearing caps No. 2 and 4 alternately crosswise, screw the nuts onto the mounting studs, but do not tighten the nuts completely. Install bearing caps No. 5, 1 and 3 and pre-tighten the fastening nuts, taking into account the position of the caps of these bearings that are offset relative to the axis. Install the bearing caps completely into their seats, lightly hitting the front flange of the camshaft with a mallet. Finally tighten the nuts securing the bearing caps to the required torque, starting with the bearing cap nuts No. 5.
Press in a new camshaft seal using drift 10 203. Install the camshaft sprocket and tighten its bolt to the required torque. Screw in the spark plugs
To remove the camshaft drive belt, disconnect the wires from the battery terminals. Loosen the alternator mounting bolts and remove the drive belt. Remove the crankshaft pulley. Remove toothed belt guards. Disconnect the high voltage wire harness. Remove spark plugs from cylinder head sockets. Turn the crankshaft to the TDC position on the compression stroke of the 1st cylinder, aligning the mark on the flywheel with the alignment protrusion on the clutch housing and setting the mark on the camshaft pulley to the level of the cylinder head gasket. Loosen the nut securing the idler axle. Remove the camshaft timing belt.
Note. Do not turn the camshaft when any of the pistons is at TDC.
When installing, turn the camshaft to the TDC position on the compression stroke of the 1st cylinder, putting a mark on the camshaft pulley at the level of the cylinder head gasket (pic. 2-26). Install the intermediate shaft toothed pulley in the correct position, aligning the mark on it with the TDC mark of the piston of the 1st cylinder on the temporarily installed crankshaft pulley. Set the crankshaft to the position corresponding to the TDC of the compression stroke of the piston of the 1st cylinder according to the marks on the flywheel and on the clutch cover. Fit the camshaft timing belt onto the pulleys. Adjust the belt tension by turning the tension roller on the axis in the direction opposite to the direction of rotation of the toothed belt (pic. 2-27).
Rotate the crankshaft two turns and check that the toothed belt tension is correctly adjusted (pic. 2-28). Remove the crankshaft pulley and install the toothed belt guards. Install the crankshaft pulley. Put on the alternator drive belt and adjust its tension. Tighten the alternator mounting bolts. Screw in the spark plugs and connect the high voltage wires. Check and, if necessary, adjust the ignition timing. Connect the battery.
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