Troubleshooting of engine parts VAZ-2123

After the engine has been dismantled, all parts must be thoroughly washed with petrol and carbon deposits removed.

Before engine reassembly, the cylinder block, the cylinder head and all the main components for engine assembly must be inspected.

Checking the cylinder block for leaks

1. Check the cooling jacket of the block for leaks. To do this, plug all the openings in the block with wooden plugs, except one, to which a compressed air supply hose is connected.
2. Immerse the block in a bath of water and supply compressed air at a pressure of 1.5 atm. Air bubbles will appear at leak points.
3. Check the oil galleries of the block for leaks in the same way.

If a leak is detected, the block must be replaced.

Checking the cylinders

1. We measure the cylinder diameter with a bore gauge in four belts (at distances of 8, 15, 50, 90 mm from the upper face of the block) and in two directions (parallel and perpendicular to the crankshaft axis).
2. If the wear exceeds 0.15 mm, the block must be bored to the repair size of 0.4 or 0.8 mm.

In belt 1 the cylinders hardly wear at all. From the difference in measurements in the first and the other belts, the amount of cylinder wear can be judged.

Checking the pistons and the crankshaft

1. To determine the wear of the piston skirt, we measure the diameter with a micrometer in the plane perpendicular to the piston pin axis, at a distance of 55 mm from the piston crown.

2. We measure the diameters of the crankshaft big-end journals with a micrometer.

3. We measure the diameters of the crankshaft main journals.

The crankshaft journals are ground to the nearest repair size if their out-of-roundness is more than 0.03 mm, and also if there are scores and scratches on the journals.

4. After grinding, the oil gallery plugs must be removed and abrasive residues and deposits eliminated.
5. We fit new plugs.

Checking the flywheel

The flywheel surfaces mating with the crankshaft and with the clutch driven plate must be free from scratches and scores and perfectly flat.

1. If the working surface 3 of the flywheel under the clutch driven plate has scratches, this surface must be turned, removing a layer of metal not more than 1 mm thick.
2. Then turn surface 2, maintaining the dimension 0.5±0.1 mm and ensuring that surfaces 2 and 3 are parallel to surface 1. The non-parallelism tolerance is 0.1 mm.
3. After turning, we mount the flywheel on a drift, centring it by the seating hole with support on surface 1, and check the runout of planes 3 and 2. At the extreme points the dial gauge must not show runout exceeding 0.1 mm.
4. We pay attention to the tightness of the ring gear fit and the condition of its teeth. If the ring gear can be moved on the flywheel or the teeth are heavily worn, replace the flywheel together with the ring gear. Replacing the ring gear is quite complicated and requires certain skills of the operator, as well as the use of special tools.

Fitting the flywheel

1. We fit the flywheel and the removed assemblies and parts in the reverse order to removal.
2. The flywheel can be fitted to the crankshaft in two opposite positions determined by the location of the mounting holes. At the manufacturing plant it is balanced together with the crankshaft, therefore it must be fitted strictly in its original position.
3. For correct fitting, a mark in the form of a conical recess is made on the flywheel; when fitting, it must be oriented to the same side as the big-end journal of the 4th (1st) cylinder.
4. If the crankshaft was turned after the flywheel was removed, set the piston of the 4th cylinder to TDC of the compression stroke, then turn a further half revolution and fit the flywheel onto the crankshaft with its mark pointing vertically downwards.
5. Tighten the flywheel mounting bolts evenly in a crosswise sequence to a torque of 60.96-87.42 N·m (6.22-8.92 kgf·m).