Camshafts
1. To check the runout of the camshaft, two instrumental prisms and a dial gauge are required. Usually such a tool is in metalworking workshops. therefore, if you have a suspicion that its l is curved, contact such a workshop. Compare the result of the beat measurement with technical data. If the runout really exceeds the allowable limit, then the shaft must be replaced.
2. Inspect the shaft journals and the bores under them for wear and tear. If the bores are worn out, you will have to replace the entire cylinder head with covers. Measure the diameter of the shaft journals with a micrometer (pic. 21.2).
3. Check the wear of the shaft cams:
- A) Inspect the cam lobe and barrel for scoring and uneven wear, pitting, and chipping.
- 6) If the cam is badly worn, replace the shaft, but first try to find out the cause of the increased wear. Cam wear is usually caused by lubrication problems or dirt in the oil. Look for abrasive particles in the oil, the oil pump is in good condition, and the oil channels are not clogged.
- V) Measure the cam height with a micrometer (pic. 21.3). If the wear of at least one cam exceeds the allowable rate, replace the shaft.
4. Measure the clearances in all shaft bearings using "plastic probe" (pic. 21.4, a, b). Compare your results with technical data. If the clearance in at least one bearing exceeds the allowable value, replace the shaft and measure the clearances again. If, in this case, the clearances are greater than specified, replace the cylinder head.
Pushers
5. Where mechanical (not hydraulic) tappets, wipe off the oil from the tappets, mark the shims and remove the tappets together with the shims. Store the support caps, tappets and shims in such a way that they can be reinstalled in the future.
6. Inspect the sliding surfaces of the tappets for wear, pitting, scuffing, and signs of overheating (pic. 21.6). As a rule, if at least one of the pushers is defective, it is recommended to replace the entire set of pushers.
7. Measure the outer diameter of each pusher and the inner diameter of the corresponding bore. Determine the clearance by subtracting the tappet diameter from the bore diameter. Compare the resulting value with technical data. If the gap exceeds the allowable value, replace the pushers or cylinder head. Store hydraulic tappets in a container of oil until assembly "upside down".