Repair of the VAZ-2123 engine

After removal from the vehicle, we install the engine on a test stand.

Using a ring spanner or a 17 mm socket, we slacken the nut securing the power unit mounting to the bracket.

We remove the mounting.

Using a 13 mm spanner, we remove the bolt securing the starter shield to the bracket.

We remove the four nuts securing the bracket to the cylinder block.

We remove the bracket from the cylinder block studs.

We remove the four nuts and take off the left engine mounting bracket.

Having slackened with a 13 mm spanner the two nuts securing the starter shield to the exhaust manifold, we remove the shield.

We remove the ignition module, the knock sensor, the alternator;

• the alternator bracket; the oil filter bracket; the crankcase ventilation oil separator;
• the oil pump; the coolant pump; the flywheel and the clutch housing cover;
• the cylinder head assembly with the receiver, the inlet pipe and the exhaust manifold;
• the timing drive chain, the chain tensioner shoe, the crankshaft sprocket; the oil pump drive shaft.

Using a 10 mm socket, we remove the six bolts securing the rear crankshaft oil seal retainer to the cylinder block.

Using a screwdriver, we prise up the retainer lugs and remove it together with the oil seal.

We remove two square-headed bolts from the oil seal cover.

We remove the gasket.

Using a 10 mm spanner, we remove the bolt securing the oil separator drain pipe bracket and take off the bracket.

Using a 14 mm socket, we remove the two connecting rod cap nuts.

We tap the connecting rod cap surfaces with a plastic hammer.

We remove the connecting rod cap.

We remove the lower connecting rod bearing shell.

Resting on the ends of the connecting rod bolt shanks, we slide the connecting rod lower eye off the crankshaft journal.

Resting the wooden handle of a hammer against the connecting rod lower eye, we push the piston into the cylinder.

We remove the piston with connecting rod from the cylinder. We also remove the pistons from the other cylinders.

We spread the upper compression ring gap.

We remove the upper compression ring.

We also remove the lower compression ring.

We remove the two oil control ring rails.

We remove the oil control ring expander.

To separate the piston from the connecting rod, we prise up the piston pin circlip with a screwdriver.

We extract the circlip from the piston boss groove. We remove the second circlip in the same way.

Having shifted the piston pin, we extract it from the holes in the piston and the connecting rod eye.

We separate the piston from the connecting rod.

If the parts are to be reused, they must be marked.

Using a 17 mm socket, we remove the two bolts securing the crankshaft main bearing cap.

We remove the main bearing cap.

We remove the main bearing shells from the cap.

We also remove the remaining main bearing caps.

We extract the crankshaft from the block.

We remove the thrust half-washers from the grooves of the rear cylinder block support.

We remove the upper main bearing shells of the crankshaft from the cylinder block supports.

Inspection of the engine parts

After dismantling the engine, all parts must be thoroughly washed in petrol and the carbon deposits removed.

Using a bore gauge, we measure the cylinder diameter in four zones (at 8, 15, 50, 90 mm from the upper block plane) and in two directions (parallel and perpendicular to the crankshaft axis).

If the wear exceeds 0.15 mm, the block must be bored to the repair size of 0.4 or 0.8 mm.

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

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

We measure the diameters of the crankshaft main journals.

The crankshaft journals are ground to the nearest repair size if their ovality exceeds 0.03 mm, and also if there is scoring or scratching on the journals.

After grinding, the oilway plugs must be removed and abrasive residue and deposits eliminated.

We fit new plugs.

Engine reassembly

We reassemble the engine in the reverse order. We fit new crankshaft bearing shells according to size.

In the first, second, fourth and fifth block supports we fit the upper main bearing shells with grooves, and in the third support — shells without a groove on the inner surface.

We apply a thin layer of engine oil to the working surfaces of the main bearing shells and lay the crankshaft in place.

We insert the thrust half-washers, lubricated with engine oil, into the grooves of the fifth support.

On the front side of the fifth support we fit a steel-aluminium half-washer, and on the rear side — a metal-ceramic one (yellow).

The working surfaces of the half-washers with the anti-friction coating (on which the grooves are made) must face the thrust surfaces of the crankshaft.

We fit the main bearing caps with shells in accordance with the marks on the outer surface of the caps (numbering is from the camshaft drive side).

The shell locating lugs must be on the same side.

We tighten the main bearing cap bolts to a torque of 68.31–84.38 N·m (6.97–8.61 kgf·m).

Pistons are matched to cylinders by classes. The cylinder diameter class, designated by letters, is stamped on the lower plane of the block.

The classes of the piston skirt diameter and the piston pin bore are marked on the piston crown.

The arrow on the piston crown, when fitting the piston into the cylinder, must point towards the timing drive.

Using a set of flat feeler gauges, we check the piston ring gap.

We lubricate the piston grooves with engine oil. We fit the rings onto the pistons.

Before assembling the connecting rod and piston group, the pins must be matched to the pistons and connecting rods.

On new parts, the class of the pin bores in the connecting rod and piston must correspond to the pin class.

On used parts, for correct mating, the piston pin lubricated with engine oil must enter the piston or connecting rod bore under hand pressure and must not fall out when the pin is vertical.

To check the piston ring gap, we insert the ring into the cylinder and align it with the piston crown.

If the ring bears the mark «ВЕРХ» (Top) or «ТОР» (Upper face) near the gap, we fit the ring with the mark upwards. The rings must rotate freely in the grooves, without sticking.

We arrange the rings as follows:

• the upper compression ring gap is oriented at 45° to the gudgeon pin axis;
• the lower compression ring gap — at 180° to the axis of the upper ring gap;
• the oil control ring gap — at 90° to the axis of the upper compression ring gap (the expander joint is placed on the side opposite the gap).

Before fitting the CRP parts, we lubricate the cylinders, the pistons with rings and the big-end bearing shells with engine oil.

We fit the lower compression ring with the groove downwards.

Before fitting the piston into the cylinder, we put an adjustable sleeve onto the piston, tighten the sleeve and compress the rings.

We fit the piston with connecting rod into the cylinder, orienting the piston with the arrow on its crown towards the timing drive.

With the hammer handle we push the piston into the cylinder.

Having removed the sleeve, we push the piston fully into the cylinder with the hammer handle.

We check from the other side of the block the seating of the connecting rod lower eye with the shell on the crankshaft journal.

When fitting the connecting rod caps, the numbers on the connecting rod and cap must coincide and be on the same side of the connecting rod.

We tighten the connecting rod securing nuts to a torque of 43.32–53.51 N·m (4.42–5.4 kgf·m).

Running-in of the engine after repair

The repaired engine is subjected to bench tests (running-in) without load according to the following cycle:

• 750–800 min^-1 — 2 min;
• 1000 min^-1 — 3 min;
• 1500 min^-1 — 4 min;
• 2000 min^-1 — 5 min.

Having installed the engine on the stand and started it, check the following:

• whether there is any leakage of coolant or fuel between the mating parts, from pipe joints and through gaskets;
• the oil pressure and whether there is any oil seepage through gaskets;
• the idling speed;
• whether there are any abnormal knocks.

If abnormal knocks or faults are detected, stop the engine, rectify them, and then continue the tests.

If oil seeps through the gasket between the cover and the cylinder head or through the gaskets between the engine sump, cylinder block and covers, tighten the securing bolts to the recommended torque.

If the oil leak does not stop, check whether the gaskets are fitted correctly and replace them if necessary.