Checking the crankshaft
the T4 Conveyor crankshaft for visible damage, and then measure the diameters of the main and connecting rod journals.
These necks have three repair sizes in diameter. In some cases, even on new engines, repair liners are used. Hang the crankshaft on a wire and "sound" check for invisible cracks. For reliability, you can call a friend - a musician. A crankshaft with a crack (thudding sound) must be replaced. ♦ Mount the crankshaft at the centers of the lathe (or place the outer journals on prisms) and measure the runout on the central journal (with a dial gauge).
It should not exceed 0.06 mm. Otherwise, replace the T4 crankshaft. If the runout is normal, then measure the gap between the bearings and the shaft journals: ♦ Clean the half bearings thoroughly and place them in the housing or in the connecting rods.
♦ Place plastic calibrated wires “Plastigage” on all shaft journals and put on caps with inserted half-inserts, tighten nuts to 65 Nm.
♦ After installing the covers, do not rotate the crankshaft.
♦ Compare the width of the flattened wire at its widest point with the gauge ruler supplied with the wires (see fig. 112). If the clearance is greater than 0.17 mm for the main bearings and 0.12 mm for the connecting rod bearings, you will need to replace the bearings. At the same time, pay attention to the actual diameter of the crankshaft journals, if the journals are worn out more than allowed, then they will have to be reground to the nearest repair size, changing the liners accordingly.
Rice. 112 Measuring the clearance in the crankshaft bearings Conveyor with "Plastigage" wires
It is more convenient to measure the clearance of connecting rod bearings in two steps by turning the corresponding journals to a position convenient for work.
In any case, it is recommended to replace both the main and connecting rod bearings with each disassembly. The soft surface layer of the bearings accumulates hard wear particles, which leads to accelerated wear of the shaft journals in the future.