Secure the indicator holder to the mating surface of the cylinder head (figure 187). Pull the valve out of the sleeve until the end of the rod is flush with the end of the sleeve on the other side of the head.
Rock the valve transversely by the valve plate and read the indicator. If they exceed 1.3 mm, the bushing should be replaced. Before replacing the bushing, assess the overall technical condition of the cylinder head. Small cracks between the valve seats are acceptable if the width does not exceed 0.5 mm (see figure 47). To replace the bushing, it is necessary to press it out of the cylinder head from the camshaft side using a rod equal to or very close in diameter to the bushing diameter. The work can be made easier by preheating the head. The rod used for pressing out must have a groove of a smaller diameter corresponding to the diameter of the hole. The mandrel for performing this operation is shown in Figure 188. Together with the replacement of the bushings, the valves are also replaced, and the parameters of the valve seats are adjusted by milling (see below). Lubricate the new bushings well and press them into the cold cylinder head from the camshaft side until the flange of the larger diameter rests against the cylinder head. From this point on, the force of pressure on the mandrel must not be increased, as this may lead to the flange being cut off.
After installing the bushing, process its internal diameter with a special reamer. If you do not have such a reamer, you can use another 8 mm reamer for the intake and exhaust valves.
Caution! Valve seats should only be milled after replacing the bushings.
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