Removing the head from the engine was discussed in the article - "Removing the cylinder head of the VAZ-2123 engine"
Dismantling the cylinder head in the article - "Dismantling the cylinder head VAZ-2123"
In this article, we will consider checking and repairing the cylinder head.
Thoroughly rinse the cylinder head and clean the oil channels of the head.
We remove carbon deposits from the combustion chambers and from the surface of the exhaust channels with a metal brush.
We inspect the cylinder head. Cracks are not allowed anywhere on the head.
If there is a suspicion of coolant entering the oil system, check the cylinder head for leaks.
To check the tightness, you need to close the holes in the cooling jacket of the cylinder head with plugs.
There is a special set of plugs A.603334. But you can, of course, do it yourself from auxiliary materials.
Pump water into the cylinder head cooling jacket under a pressure of 0.5 MPa (5 kgf / cm2).
There should be no water leakage from the cylinder head within two minutes.
You can check the tightness of the cylinder head with compressed air, for which you also install the plugs of the A60334 tool on the cylinder head.
Immerse the cylinder head in a bath of water heated to 60-80˚C and let it warm up for five minutes.
Then supply the inside of the head with compressed air at a pressure of 0.15–0.2 MPa (1.5–2 kgf / cm2). Within 1-1.5 minutes, there should be no air bubbles coming out of the head.
The valve seat chamfer shape is shown in Figures 2 and 3.
2. Inlet valve seat profile
3. Exhaust valve seat profile
The working chamfers of the seats (the contact area with the valves) must be free of pinholes, corrosion and damage.
Minor damage can be repaired by grinding the seats, removing as little metal as possible.
Grinding can be done either by hand or with a grinder.
To grind the seats, install the cylinder head on a stand, insert rod A.94059 into the valve guide sleeve and clean the chamfers of the seats from carbon deposits with countersinks A.94031 and A.94092 for exhaust valve seats and countersinks A.94003 and A.94101 for inlet valve seats.
Countersinks are put on the spindle А.94058 and are centered by the guiding rod А.94059.
These rods are available in two different diameters: A.94059 / 1 for the inlet valve guides and A.94059 / 2 for the exhaust valve guides.
Put the spring A.94069 / 5 on the guide rod A.94059, install the tapered disc A.94078 for the exhaust valve seats or the disc A.94100 for the inlet valve seats on the spindle A.94069, fix the spindle in a grinder and grind the valve seat.
4. Grinding the working chamfer of the valve seat
Narrowing of the working chamfer of the valve seat with a countersink installed on the spindle A.94058
At the moment the wheel touches the saddle, the machine must be turned off, otherwise vibration will occur and the chamfer will be incorrect. It is recommended to dress the wheel more often with a diamond.
For exhaust valve seats, bring the width of the working chamfer to the values indicated in Figure 2 with the A.94031 countersink (angle 20˚) and the A.94092 countersink, which removes the work hardening on the inner diameter.
Countersinks are put on the spindle А.94058 and, as in grinding, are centered with the rod А.94059.
At the inlet valve seats, bring the width of the working chamfer to the values indicated in Figure 3, first by machining the internal chamfer with an A.94003 countersink (Figure 5) until a diameter of 33 mm is obtained, and then a 20˚ chamfer with an A.94101 countersink until a working chamfer of width 1 is obtained. 9-2 mm.
Valves and valve guides
Remove carbon deposits from valves. Check for a deformed stem or cracks in the valve poppet. Replace the damaged valve.
Check the condition of the valve chamfer. For minor damage, it can be sanded, maintaining a bevel angle of 45 ° 30 '± 5'. In this case, the distances from the lower plane of the valve disc to the base diameters (36 and 30.5 mm) should be within the limits indicated in Figure 6.
6. Limit dimensions when grinding valve chamfers
7. Pressing out the guide bushings
Check the clearance between the guide bushings and the valve stem by measuring the diameter of the valve stem and the bore of the guide bush.
Design clearance for new bushings: 0.022-0.055 mm for intake valves and 0.029-0.062 mm for exhaust valves; the maximum permissible limiting clearance (with wear) is 0.3 mm, provided there is no increased noise of the gas distribution mechanism.
If the increased clearance between the guide bush and the valve cannot be eliminated by replacing the valve, then replace the valve bushings using a mandrel A.60153 / R for pressing and pressing (Figure 7).
Press in the guide bushings with the retaining ring put on until it stops in the cylinder head body.
After pressing in, unfold the holes in the guide bushings with reamers A.90310 / 1 (for inlet valve bushings) and A.90310 / 2 (for exhaust valve bushings).
When repairing the engine, always replace the oil deflector caps of the guide bushings with new ones.
Replace damaged valve stem seals on the removed cylinder head. Use mandrel 41.7853.4016 to press on the caps.
Make sure that there are no cracks on the springs and their elasticity has not decreased, for which check their deformation under load (Figure 8).
8. Basic data for checking the outer (a) and inner (b) valve springs
9. Scheme of checking the spring of the lever
For lever springs (Figure 8), size A (spring in a free state) should be 35 mm, and size B under a load of 51-73.5 N (5.2-7.5 kgf) - 43 mm.
Cylinder head retaining bolts
If the bolts are reused, they will pull out. Therefore, check if the length of the bolt rod (excluding the head length) does not exceed 117 mm and, if it is longer, replace the bolt with a new one.
Check the condition of the working surfaces of the lever mating with the valve stem, the camshaft cam and the ball end of the adjusting bolt.
If these surfaces are scored or scratched, replace the lever with a new one.
If deformation or other damage is found on the arm adjusting bolt bushing or bolt itself, replace the parts.