4.3.21. Check of a condition of camshafts, pushers of valves and bearings

 PERFORMANCE ORDER

1. Check bearing surfaces under installation of camshafts for existence of cavities, scratches, zadir and other signs of excessive wear. In case of detection of defects it is necessary to replace a head.

2. Measure the outer diameter of each of bearing necks of shaft. Write down results of measurements and compare them to the nominal rates specified in Specifications. Measure internal diameters of bearings in heads of cylinders and subtract from results of the last measurements results corresponding the first. The received difference will make the size of gaps in bearings of shaft. Compare the obtained data with requirements of Specifications. In case of need make replacement of shaft and/or heads.

3. Estimate the size of a radial beating of shaft, stacking them in V-shaped blocks and using the dial measuring instrument of plunger type. Rotate a shaft in blocks slowly, write down the taken readings and compare them in nominal rates (see Specifications). In case of need replace the corresponding shaft.

4. By means of a micrometer measure height of cams of shaft. Compare results of measurements to requirements of Specifications, then subtract them from the last for the purpose of definition of degree of wear of cams. If wear exceeds extreme admissible value (see Specifications), replace the corresponding shaft.

5. Estimate a condition of working surfaces of pushers of valves.

If the contact surface of a pusher is worn-out, it makes sense to estimate also a condition of a working ledge of the corresponding cam of a distributive shaft / an adjusting washer on DOHC engines.

On SOHC engines pushers should be held vertically in order to avoid hit of air in them (see the Part SOHC Engines of the present Chapter).

6. By means of a micrometer measure the outer diameter of each pusher. Compare results of measurements to requirements of Specifications. Replace the pushers which are worn out over an admissible limit.

7. Measure diameter of each pusher, compare results of measurements to requirements of Specifications. In case of need replace assembly of guides (SOHC engines), or a head of cylinders (DOHC engines).

8. Subtract sizes of outer diameters of pushers from sizes of internal diameters of the corresponding nests in a guide/head for the purpose of definition of a gap of landing of pushers in nests, - at installation of new components (pushers, a guide/head) the probability of an exit of this parameter out of limits of admissible values is not excluded.
9. On SOHC engines estimate degree of wear of yokes and their axes (see the Part SOHC Engines of the present Chapter). At excessive wear of overlays of a yoke are subject to replacement - at all do not make attempts of carrying out their recovery wear.
10. Remember that the condition of all components, - new or suitable for the further use old before installation has to be without fail checked.