We examined the removal of the cylinder head in the article Removal and installation of the cylinder head of the VAZ-2112 engine. In this article, we will look at the disassembly and assembly of the cylinder head.
When disassembling the cylinder head, the parts must be marked and folded in order.
With a head of 8, we unscrew the 20 bolts securing the camshaft bearing housing
Remove the camshaft bearing housing. We take out the guide pipes of the spark plugs from the body
A belt is made near the first journal on the intake camshaft
We take out the camshafts with oil seals
We remove two plugs of the ends of the camshafts
Using a magnet, we remove the hydraulic pushers from the nests and put them in order
We unscrew with a 13 key two nuts securing the cooling system pipe
Remove the branch pipe
Unscrew the coolant temperature sensor with a 21 key
We put a wooden block under the valve plates.
We install a device for drying the valves.
We install the desiccant foot bearing on the valve spring plate, and put the hook lever behind the head of the bolt screwed into the hole in the cylinder head, intended for fastening the bearing housing.
Press down on the lever and squeeze the valve spring. We extract two valve cracks with tweezers
Removing the spring plate
We take out the spring
We use special forceps to remove the slinger caps.
Remove the valve seals from the bushings
We take out the valves from the cylinder head guide bushings and put them in order
Check the flatness of the surface adjacent to the cylinder block.
To do this, place the ruler with its edge on the surface of the head, first in the middle along and then diagonally, and measure the gap between the surface of the head and the ruler with a feeler gauge. If the gap is greater than 0.1 mm, the mating surface can be sanded.
Similarly, check the flatness of the mating surfaces of the block head under the intake manifold
Check the flatness under the collector. The flatness of these surfaces should not exceed 0.1 mm
To check the tightness of the block head, plug the hole in the head for the thermostat socket.
This can be done, for example, by placing a blank spacer made of thick cardboard under the socket and tightening its fastening nuts.
Reinstall the coolant temperature gauge sensor if it was turned out.
We clean the valve from carbon deposits.
We visually check the condition of the valve. We replace the valve if there are deep risks on the working chamfer 1, cracks, deformation of the rod 3, warpage of the valve plate 2, traces of burnout.
Small marks and scratches on the valve chamfer can be removed by lapping the valves. To do this, apply a continuous thin layer of lapping paste to the valve chamfer.
We put a pre-selected spring on the valve stem and insert the valve into the guide sleeve from the side of the combustion chamber.
We apply graphite grease to the valve stem itself so that the lapping paste does not get on the surface of the valve sleeve.
We put on the valve stem a valve grinding device or a reversible drill with a hose tip to connect to the valve.
Turning on the drill at the minimum speed (in reverse mode) or rotating the device (in the case of manual lapping) alternately in both directions by half a turn, grind the valve, periodically pressing it against the seat, then weakening the pressing force.
The external sign of a satisfactory lapping is a monochromatic matte gray color of the working chamfer of the valve.
There should also be a solid gray strip on the valve seat.
After lapping, thoroughly wipe the valve and valve seat from the lapping paste.
Check the tightness of the valve, for which install it with springs and crackers in the head.
Then put the head with the combustion chambers up, plug the plug hole and pour kerosene into the combustion chamber.
If, within 3 minutes, kerosene does not seep into the channel of the block head, the valve is tight.
In order to check the head of the block for cracks, you need to bring a hose for supplying compressed air to one of the holes of the cooling jacket.
Seal all holes in the head with wooden plugs.
Lower the head into a bath of water and supply compressed air at a pressure of 1.5 atm.
Air bubbles will come out where there are cracks.
Inspect the valve pushers. If there are scratches or other defects, replace the hydraulic pushers. Measure the outer diameters of the pushers, replace the worn pushers.
On the working surfaces 2 there should be no scoring, nicks, scratches, traces of stepped or uneven wear, metal rubbing.
Hydraulic pushers with such defects must be replaced.
On surfaces 2, concentric running-in marks with camshaft cams are allowed.
Check the clearances between the guide bushings and the valves.
The clearance is calculated as the difference between the bore diameter in the sleeve and the valve stem diameter. Clearances between the valve and the guide sleeve, mm:
- nominal for inlet and outlet valves - 0.018-0.047
- maximum allowable for inlet and outlet valves - 0.3
If the gap has not reached the maximum allowable, you can try to eliminate it by replacing the valve.
If this cannot be done or the clearance exceeds the maximum allowable, replace the guide bush.
To do this, press out the defective bushing from the side of the combustion chamber with a mandrel, having previously measured the height of the protrusion of the upper part of the bushing above the surface of the block head.
Cool the new bushing, for example, using carbon dioxide, lubricate it with oil, insert it into a special mandrel and press it in from the side of the camshaft so that the protrusion height of the upper part of the bushing corresponds to the measured value.
Reamer the bore in the bushing using a reamer to 7.0 - 7.015 mm for inlet and outlet valves.
Cylinder head assembly
We assemble the head in reverse order, taking into account the following:
We use a special mandrel to press in the slinger valves.
Lubricate the new slinger cap and press it onto the valve guide
We install the block head on the engine - (Removal and installation of the cylinder head of the VAZ-2112 engine)
Installing valve pushers
Lubricate the camshaft bearings and hydraulic pushers
Устанавливаем распределительные валы в опоры головки так, чтобы кулачки 1-го цилиндра были направлены в сторону от толкателей клапанов
We install the camshafts in the head supports so that the cams of the 1st cylinder are directed away from the valve lifters
Apply sealant to the bearing housing surface
Places of applying sealant to the bearing housing
Install the bearing housing and tighten the mounting bolts evenly crosswise
Having lubricated the O-rings of the guide pipes with engine oil, we install the pipes
On the other side of the cylinder head, we press in the plugs.