Cylinder head inspection [Toyota Carina T170]

Determine the wear of all cylinder head parts. Clean the cylinder head surfaces thoroughly (remove the remains of the old sealant with a scraper without damaging the cylinder head material). The control should be carried out in accordance with the following instructions.

Valve springs

To check the valve springs perfectly, a spring tester should be used. If one is not available, a used spring can be compared with a new spring. To do this, clamp two springs together in a vice and slowly tighten the vice. If both springs are compressed equally, this is a sign that they have approximately the same tension. But if the old spring is compressed significantly more than the new one, this is a sign of fatigue and the springs must be replaced as a set. The free length of the spring can be measured with a caliper. The springs must have a certain length, which is given in the tables of sizes and adjustments. Install the springs one by one on a smooth surface (glass plate) so that the closed coil is on the bottom side. Install a steel angle next to the spring. Measure the gap between the springs and the angle at the top (Fig. 46). The tolerance is different for each type of engine. If the tolerance is exceeded, the spring is skewed.

Valve guide bushings

Clean the guide bushings by pulling a rag soaked in gasoline through the guides in both directions. It is better to clean the valve stems with a rotating wire brush, inserting it into the chuck of an electric drill and holding the valve stem next to it. Insert the valves into the holes one by one. To check the play of the valve stems in the holes, you need to have a dial indicator and a caliper:

• Measure the inner diameter of the guide bushings with a dial indicator, as shown in Fig. 47. The result should be between 6.01 mm and 6.03 mm (on all engines).

• Measure the outside diameter of the valve stems at the three locations and directions shown in Fig. 48. The nominal outside diameter of the exhaust valves is 5.965–5.980 mm, and that of the intake valves is 5.970–5.985 mm (on all engines).

• Subtract the valve stem diameter from the inside diameter of the guide bushings. The result is the valve stem clearance in the bores, which should not exceed 0.08 mm for intake valves and 0.10 mm for exhaust valves.
• Before replacing the guide bushing, check the general condition of the cylinder head. Cylinder heads with small cracks between the valve seats or between the valve seat and the first thread of the spark plug hole can be reinstalled and treated if the cracks are no wider than 0.5 mm. Also check for deformation of the cylinder head surface, which will be described below.

To replace the guide bushing, knock the old bushing out from the top of the cylinder head. Before removing the guides, consider the following points:

• Heat the cylinder head to 80-100°C and knock out the old guide bushing from the top into the combustion chamber. The punch should have a notch at the end corresponding to the inner diameter of the guide bushing. So the guide bushing should be knocked out at an angle, install the cylinder head as shown in Fig. 49.

• Measure the inside diameter of the cylinder head bore using a dial indicator. If the measurement is between 11.000 mm and 11.027 mm, a bushing with the nominal outside diameter can be installed. If the diameter exceeds 11.027 mm, a guide bushing with an increased outside diameter must be installed. This means that the holes for the guide bushings must be bored in the workshop. Do not press into holes with an increased outside diameter. When replacing the valve guide bushings, the valves are also replaced and it is necessary to grind the valve seats. Clean the inside surfaces of the holes thoroughly, grease the new guides well and drive them from the camshaft side into the cylinder head heated to 100°C so that the upper end protrudes above the upper surface of the cylinder head by the dimension shown in Fig. 50, on a 1.6 liter engine 12.7-13.1 mm and on a 2.0 liter engine 8.2-8.4 mm.

When replacing the valve guide bushing, mill the valve seat. If lapping of the valve seats is not possible, do not replace the valve guide bushings.

Valve seats

Check the wear of the valve seats. Minor signs of wear can be eliminated with a 45° cutter. However, if the wear is severe, the valve seats should be re-milled. The specified angles are shown in Fig. 51. The seat width applies to both engine types. However, an angle should be provided for correcting the valve seat height, i.e. a 60° cutter should be used (1.6L engine) or 75° (2.0L engine). As already mentioned, when installing new valves, the valve seats can be milled clean. First, mill a 45° angle and then lightly process the upper and lower edges of the seat with a 30° and 60° or 75° cutter to reduce the width of the seat and move it to the middle. The width of the working chamfer of the seat should be 1.0 - 1.4 mm for inlet and outlet valves. The finished seats must be lapped. To do this, apply grinding paste to the surface of the valve seat and insert the valve into the seat. Install a suction cup on the valve and turn the valve in different directions (Fig. 52). After lapping, thoroughly clean all parts from paste and dirt and check the valve seat at the valve head and the seat chamfer. A continuous matte ring characterizes the width of the valve seat and should be visible on both parts. Apply a few lines with a pencil on the "ring" on the valve head. The dashes should be applied in a circle at a distance of 1 mm. After this, carefully lower the valve into the guide sleeve and seat and turn the valve by 90°, pressing the valve (use a suction cup for this). Pull out the valve and check if the pencil marks have been removed from the chamfer. If the valve seat width is within the specified tolerances, the head can be reinstalled. Otherwise, machine the valve seats or replace the head.

Valves

Minor damage to the valve head surfaces can be eliminated by grinding the valves in the cylinder head seats as described above. Measure the valves according to the data given in the dimension and adjustment tables and replace all valves whose dimensions are outside the tolerance. In this case, special attention should be paid to the length of the valves. All data are taken from the dimension and adjustment tables. If the length is less than the minimum permissible, replace the valves. If the ends of the valve stems are worn, they can be ground on a grinding machine, only if the correction requires removing no more than 0.50 mm of stem material and the dimensions will ultimately correspond to the specified tolerances. The valve plate can be ground on a grinding machine, provided that the dimension between the arrows (Fig. 53) is still 0.5 mm, if the valve can still be installed. Grind an angle of 44.5° (the valve plate chamfer angle is less than the valve seat chamfer angle).



The text is taken from the specified website: ToyotaMan.ru

Cylinder head

Thoroughly clean the cylinder head and cylinder block surfaces and check for skew of the cylinder head surface. To do this, place a ruler on the head (Fig. 54) and use feeler gauges to determine the gaps along, across and diagonally across the cylinder head surface. If a feeler gauge larger than 0.05 mm can be inserted, the cylinder head must be replaced. The same check must be carried out for the surface onto which the manifold is installed. Here, too, the permissible gap is 0.05 mm. In Fig. 54, the dashed lines show the directions in which measurements must be taken. Nowhere must the gap exceed the specified maximum value. The skew of the surfaces in contact with the manifolds must not exceed 0.1 mm.

Camshafts

Place the camshafts with the journals of the outer bearings in prisms or clamp them in the centers of a lathe, as shown in Fig. 55, and install a pointer indicator at one of the middle journals. Slowly turn the camshaft and read the indicator. If the deviation of the pointer is more than 0.04 mm in one revolution, (on all engines), the camshaft must be replaced as it cannot be repaired. Check the integrity of the bearing journals and the surface of the camshafts. If there is no external damage, measure the height of the cams and the play of the bearings:

• The height of the cams is measured using a micrometer, as shown in Fig. 56. The specified dimensions and wear limits are given in the tables of dimensions and adjustments.

• Before checking the bearing play, check for any delamination of the bearing metal or formation of cracks. If the covers are damaged, replace the covers, camshafts and cylinder head.
• Clean the bearing caps and camshaft journals and sort the caps by bearing numbers.
• The bearing clearance is measured using a PLASTIGAGE plastic hair. Place the hair along the entire length of the journals (Fig. 57) and install the caps one by one. The arrow on all caps must point forward and the cap numbers must correspond to the bearing numbers.

• Tap the covers carefully with a hammer and insert the bolts. Tighten the bolts from the middle outwards to a tightening torque of 13 Nm (engine 4A-F/FE), or 19 Nm for the 3S-FE engine. No mistakes. The camshaft must not be turned.
• Unscrew the bearing caps again and immediately check whether there is a PLASTIGAGE hair left on the cap. Otherwise, it will also stick to the bearing journals.
• Use the template from the PLASTIGAGE kit to measure the width of the crumpled plastic hair at its widest point (Fig. 58 or 59). It provides minimal bearing clearance. If clearance is more than 0.10 mm, replace the cylinder head and/or camshaft.

• The measurement of the axial clearance of the camshafts is carried out in accordance with the instructions given in the disassembly chapter (see also Fig. 32). If the clearance exceeds 0.25 mm (determined during disassembly), replace the camshaft and/or cylinder head. On both engines, the engagement play of both camshaft gears should be checked. To do this, insert the camshaft without the secondary gear and install a dial indicator as shown in Fig. 60. Turn the specified wheel in both directions and read the dial indicator. If the play is greater than 0.30 mm, replace the camshafts.

Toothed belt and gears

A belt with broken teeth must be replaced. Other defects include cracks, abrasions on the sides, or rounding of some or all wheels. In this case, you should also check the teeth of the gear wheels. Hold the belt tensioner with one hand and turn the roller with the other. If the roller jams when turning, replace the belt tensioner. The return spring of the tensioner must have a certain length. The length is measured between the inner sides of the spring hooks. On a 1.6 L engine, the spring length should be 43.3 mm; on a 2.0L engine, the spring length should be 46.1 mm. If the spring is stretched, install a new spring.

Valve lifters

Measure the internal diameter of the tappet holes in the cylinder head and the external diameter of the tappets. To do this, you need an internal and a regular micrometer. The difference in size should be no more than 0.10 mm (1.6L engine), or 0.07 mm (2.0L engine). Otherwise, the tappets must be replaced, and in the worst case, the cylinder head.