Removal and flaw detection of timing drive parts of the VAZ-2123 engine

Removal and inspection of the timing drive components of the VAZ-2123 engine

The timing drive of the VAZ-2123 engine consists of sprockets, a chain, a guide shoe, a damper and a hydraulic chain tensioner.

The engine chain is single-strand, unlike the engines of previous models.

If, with a serviceable tensioner and its shoe, and with unworn drive sprockets, the chain tension cannot be restored, it means that the chain has stretched excessively and must be replaced. When the chain tensioner shoe wears, the tensioner's operating range becomes insufficient to restore the chain tension. In this case, replace the shoe.

The damper is located inside the front part of the cylinder head on the left and is secured to it externally by two bolts. If the damper is worn or damaged, resonance vibrations of the driving chain run may occur under certain engine operating conditions, which can lead to the chain jumping over the teeth of the camshaft sprocket and serious engine damage.

Of course, if the chain has stretched and needs replacing, it is desirable to replace all the drive components as well.

Removal of the chain and sprockets of the timing drive and oil pump

We remove the cylinder head cover.
We turn the crankshaft until the mark (recess) on the camshaft sprocket coincides with the mark on the camshaft bearing housing.
We remove the crankshaft pulley.
We detach the camshaft sprocket with the chain from the camshaft.
We remove the chain from the sprocket.

The chain removal operations are shown on the engine removed from the vehicle.

Unscrewing the sump bolts — Fig. 1. Unscrewing the bolts securing the sump to the camshaft drive cover

We unscrew three bolts securing the sump to the camshaft drive cover.

Fig. 2. Removing the bracket with the roller

We remove the bracket with the roller.

Unscrewing the support roller bolt — Fig. 3. Unscrewing the bolt securing the support roller

We unscrew the bolt securing the support roller and remove it.

Unscrewing the plate bolt — Fig. 4. Unscrewing the bolt securing the plate to the alternator mounting bracket

We unscrew the bolt securing the plate to the alternator mounting bracket.

Unscrewing the upper plate bolt — Fig. 5. Unscrewing the upper bolt securing the plate

Using a 10 mm spanner, we unscrew the upper bolt securing the plate.

Fig. 6. Removing the wiring holder bracket of the crankshaft position sensor

We remove the wiring holder bracket of the crankshaft position sensor.

Unscrewing the lower plate bolt — Fig. 7. Unscrewing the lower bolt securing the plate

Using a 10 mm spanner, we unscrew the lower bolt securing the plate.

We remove the plate.

Unscrewing the timing drive cover bolts — Fig. 9. Unscrewing the bolts and nuts securing the timing drive cover

Using a 10 mm spanner, we unscrew five bolts and two nuts securing the timing drive cover to the block.

Fig. 10. Prising off the cover with a screwdriver

We prise off the cover at its lug with a screwdriver.

Removing the cover — Fig. 11. Removing the timing drive cover

We remove the cover.

We remove the cover gasket.

Unscrewing the shoe axis — Fig. 13. Unscrewing the axis of the chain tensioner shoe

Using a 17 mm socket, we unscrew the axis of the chain tensioner shoe.

Extracting the shoe — Fig. 14. Extracting the chain shoe

We extract the chain shoe.

Pulling out the chain — Fig. 15. Pulling out the timing drive chain

We pull out the timing drive chain.

Removing the sprocket from the crankshaft — Fig. 16. Removing the sprocket from the front end of the crankshaft

We remove the sprocket from the front end of the crankshaft.

Fig. 17. Pressing off the sprocket with a puller

If the sprocket is tight, we press it off with a puller.

Driving out the key — Fig. 18. Driving out the sprocket retaining key

With a punch, we drive the sprocket retaining key out of the groove.

We remove the key.

Fig. 20. Bending back the lock washer from the head of the bolt securing the oil pump drive sprocket

We bend back the lock washer from the head of the bolt securing the oil pump drive sprocket.

Unscrewing the sprocket bolt — Fig. 21. Unscrewing the bolt securing the sprocket

Holding the sprocket from turning, we unscrew the sprocket securing bolt with a 17 mm socket.

We remove the bolt with the washers.

Removing the oil pump sprocket — Fig. 23. Removing the sprocket from the shaft

We remove the sprocket from the shaft.

After inspection, we refit all the parts in the reverse order.

Fig. 24. Pressing on the crankshaft sprocket

If the crankshaft sprocket is a tight fit, by tightening the pulley mounting nut we press it onto the crankshaft.

Fig. 25. Further pressing on the sprocket using suitable sockets

Fig. 26. Aligning the marks on the crankshaft and camshaft sprockets

Before fitting the chain, we align the marks on the crankshaft and camshaft sprockets.

Inspection of the timing drive and oil pump chain

Wash the chain in paraffin and then check the condition of its links. Chips, cracks and other damage are not permitted on the rollers and plates. During engine operation, the chain components wear, so the chain stretches. It is considered serviceable as long as the tensioner maintains its tension, i.e. if the chain elongation does not exceed 4 mm.

Chain wear checking tool — Fig. 27. Tool 67.7824.9521 for checking chain wear (elongation): 1 - roller; 2 - adjusting nut; 3 - counterweight

We determine the chain length using tool 67.7824.9521. The tool has two stepped measuring rollers 1, onto which the chain is placed when measuring its length. One of the rollers is fixed immovably in the tool body, and the second can move under the action of the measuring force P. With the help of counterweight 3 (see Figure 27), the chain is stretched with a force of 294 N (30 kgf) or 147 N (15 kgf). Adjusting nut 2 ensures the parallelism of the counterweight axis relative to the tool base.

The chain length is determined by the centre distance L of the measuring rollers 1 (see Figure 28). For a new chain, the length L is 495.4—495.8 mm. If, as a result of wear, the chain has a length of 499.8 mm, it should be replaced.

Chain wear checking diagram — Fig. 28. Diagram for checking chain wear (elongation): 1 - rollers

Measure the chain length in the following sequence:

stretch the chain with a force of 294 N (30 kgf) by placing counterweight 3 (see Figure 27) in the extreme right position, then reduce the force to 147 N (15 kgf) by moving the counterweight to the extreme left position;
repeat both operations once more;
having measured with a vernier calliper the internal distance between the measuring rollers 1 and adding the roller diameter d to it, you obtain the chain length L (the distance between the axes of the measuring rollers).

Before fitting to the engine, lubricate the chain with engine oil.

The removal and inspection of the hydraulic chain tensioner are described in the article “Removal and inspection of the hydraulic chain tensioner”.