2.3.3. Дефектовка and repair of a head of the block of cylinders and its details

If the head of the block of cylinders is disassembled, it is necessary to be defined, whether its repair is expedient. For this purpose it is necessary to spend дефектовку heads. Especially characteristic sign прожога linings of a head of the block of cylinders is, for example, deformation of its surface. Also cracks between saddles of valves or carving coils свеч ignitions can be formed. As a rule, it is not necessary to replace a block head, if the size of cracks does not exceed 0,5 mm or if the crack is only in the first coil of a carving.

For дефектовки springs of valves it is necessary to use the tester of springs recommended by the instruction. If it is absent, it is necessary to execute the following:

- To compare the used spring to the new. For this purpose to clamp both springs in a vice and slowly to clamp. If both springs appear equally compressed it is a sure sign of that they possess approximately identical elasticity;

- If it will appear that the old spring at compression becomes much shorter, than new, it testifies to weariness of a material, therefore it is necessary to replace springs in the complete set;

Fig. 36. Check of a spring of the valve on a bend

- To establish springs abreast on a smooth surface (glass) so that the closed coil was on the bottom party. To put near to a spring a steel square. To measure a backlash between a spring and a square on the top party (fig. 36) — it should not exceed 2,0 mm. Otherwise the spring is deformed and is subject to replacement.

The control of plugs of valves is necessary for spending as follows:

- To clear plugs of valves, it is necessary passing on plugs back and forth the rags impregnated in gasoline. Cores of valves then the greased valves are established serially in the apertures require careful clearing also;

Fig. 37. Check of a backlash a core of the valve/plug by means of the special tool

- To establish on the top party of a head of the block of cylinders стрелочный the indicator with the corresponding holder (fig. 37) and to squeeze out the valve from the channel while the end of a core of the valve will not rise заподлицо with directing the valve on other party of a head of the block of cylinders;

- To move a valve plate on the top party every which way and to read out indications стрелочного the indicator. If they make more than 1,0 mm at inlet valves and 1,3 mm — at final the valve plug is subject to replacement;

- As it was already mentioned, the general condition of a head of the block of cylinders check before replacement of plugs of the valve.

Fig. 38. Small cracks between saddles of valves

Defects as it is specified above are supposed, in the form of small cracks between saddles of valves (fig. 38) or between a saddle of the valve and the first coil in a carving part of a candle aperture provided that the width of cracks does not exceed 0,5 mm. At additional polishing of a head of the block of cylinders the size and, specified in fig. 39, should make not less than 135,6 mm;

Fig. 39. Height of a head of the block of cylinders ()

The note At additional polishing of a surface of a head of the block of cylinders it is necessary to choose metal in saddles of valves, otherwise valves can rest against pistons. Thus it is necessary to observe the minimum size specified more low (Saddles of valves see).

Fig. 35. The Assembly diagramme of a head of the block of cylinders without a camshaft: 1 — a hollow cylindrical pusher; 2 — crackers; 3 — the top plate of a spring of the valve; 4 — a valve spring; 5 — the directing plug of the valve with a fillet (spare part); 6 — маслоотражательный a valve cap; 7 — the established directing plug of the valve; 8 — a sealing ring of a camshaft; 9 — a head of the block of cylinders; 10 — valves; 11 — a bolt, 20 Нм; 12 — elevating скоба the engine; 13 — bolts, 20 Нм; 14 — directing for a high voltage wire; 15 — elevating скоба the engine

- Before выпрессовкой it is necessary to check up plugs of its valve at first. If the plug 5 (fig. 35 see) has a ledge выпрессовка it is spent from outside combustion chambers if such ledge is not present it выпрессовывают from a head from outside the camshaft. The old plug выпрессовывается corresponding оправкой. With a view of simplification of work the head of the block of cylinders can be heated up to 100 With. To used for dismantle оправке should be will tighten a finger approaching on diameter for installation in the plug;

- At replacement of plugs of valves subject to processing and valves (recommendations подразд see. Saddles of valves). In this case repolishing of saddles of valves should be spent;

- To grease with engine oil new directing plugs of valves and запрессовать them in a cold head of the block of cylinders from outside a camshaft. After that pressure of pressing not to increase any more, otherwise it will lead to fillet cutting;

Fig. 40. Processing of the plug of the valve by special development

- After запрессовки it is necessary to process directing plugs of valves special development 3120 (fig. 40). In case of its absence it is possible to use adjustable development. Plugs of inlet and final valves to develop to 7,0 mm. The demanded working backlash in plugs of valves is established automatically.

The note Saddles of valves are necessary for milling absolutely if plugs were replaced (see Saddles of valves).

If bearings of camshafts are worn out, it is necessary to replace a head of the block of cylinders. In this case any works on saddles of valves of a new head it is not necessary to spend.

It is necessary to check up visually saddles of all valves on absence of deterioration or corrosion traces. Insignificant deterioration can be eliminated an angular mill (45 ). Thus corners depend on engine model. For engine AEV (1,0) corners are shown on fig. 41 and 42.

Fig. 41. A saddle of inlet valves on engines in volume of 1,0 l: and = 30,8 mm, diameter; b — the maximum size of additional processing; with = 2,0 mm, width of a saddle of the valve (as much as possible admissible size); Z — a plane of a head of the block of cylinders, the bottom edge; 45 — a corner of a facet of a saddle of the valve; 30 — the top corner of a facet; 60 — a facet lower corner

Fig. 42. A saddle of final valves on engines in volume of 1,0 l: and = 27,8 mm, diameter; b — the maximum size of additional processing; with = 2,0 mm, width of a saddle of the valve (as much as possible admissible size); Z — a plane of a head of the block of cylinders, the bottom edge; 45 — a corner of a facet of a saddle of the valve; 30 — the top corner of a facet

Fig. 43. A saddle of inlet and final valves on engines in volume 1,3, 1,4 or 1,6 l: and — diameter of a saddle of the valve ("Specifications" see); b — the maximum size of additional processing; with = 2,0 mm, width of a saddle of the valve (as much as possible admissible size); Z — a plane of a head of the block of cylinders, the bottom edge; 45 — a corner of a facet of a saddle of the valve; 30 — the top corner of a facet; 60 — a facet lower corner

At other engines, including the engines, which manufacture has begun in 1996, corners of inlet and final valves the identical. The kind of these saddles in a cut is presented on fig. 43. Diameter of a saddle of the valve and has various values depending on engine model. If saddles have to be exposed to additional processing, it is necessary to adhere to the table of the sizes. It is necessary to remember that metal sample in a head of the block of cylinders for saddles should not be too deep.

For definition of the size of additional processing of saddles of valves it is necessary to spend following measurements:

- To establish the valve in the plug and to press it densely to a valve saddle;

Fig. 44. Depth gauging between the end of a core of the valve and the top edge of a head of the block of cylinders for definition of size of additional processing of saddles of valves

- To measure distance and (fig. 44) between the top point of the valve and the top edge of a head of the block of cylinders;

- To define as much as possible admissible size of additional milling on measured and is minimum admissible values; for inlet valves it makes 35,8 mm, for final valves — 36,1 mm. The given sizes are established for all engines. Subtracting the minimum value of distance from measured, we receive as much as possible admissible size b (fig. 41–43 see).

The sequence of actions at milling should be following.

- To mill a corner 30 at inlet valves or 45 at final valves, and then slightly to process the top edge at inlet valves an angular mill 45 or 60 — the bottom edge of a saddle, to reduce width of a saddle to 2,0 mm. At final valves the angular mill 30 processes only the top party of a saddle of the valve. Milling comes to an end, as soon as the size of a saddle corresponds to the specified width.

- To mill a corner 45 at inlet and final valves, and then slightly to process at saddles of both valves an angular mill 45 the top edge or an angular mill 60 the bottom edge for reduction of width of a saddle and its finishing to 2,0 mm. After milling it is necessary to check up and (or) to execute the following:

- If as a result of measurement (fig. 44 see) it is established that the given size at the inlet valve makes 36,5 mm (in comparison with the minimum distance 35,8 mm), it means that else there is a stock on the depth, equal 0,7 mm to restore working capacity of a corresponding saddle of the valve;

- If it is impossible to "smooth out" a valve saddle, it is necessary to address for consultation in HUNDRED. It is possible to order installation of rings for saddles of valves, will be established in this case as well new valves;

- To grind in the saddles which have passed additional processing of valves. With that end in view a surface of a saddle of the valve to grease with a small amount притирочной pastes and to establish the valve in a corresponding saddle. To establish on the valve a sucker and to turn its that in one, in other party (fig. 45);

Fig. 45. Grinding in of valves

- Carefully to clear after grinding in all details of pollution and притирочной pastes. To check up valve saddles on a plate and a ring. On both details the continuous matte ring which specifies width of a saddle of the valve should be visible;

- To put a pencil on a circle of a saddle some strokes on distance of 1 mm from each other. After that to lower the valve cautiously on a saddle and to turn it on 90 , to carry out it follows by pressing the valve;

- Again to take out the valve and to check up, whether there were strokes put by a pencil. If the width of a saddle of the valve is in limits of the specified values the head can be established again. Otherwise in addition to process saddles of valves or (the worst variant) to replace a head.

Small damages of a surface of plates of valves can be eliminated grinding in of valves for their installation in landing nests in a head of the block of cylinders as it is described above. Additional grinding of valves on the machine tool is forbidden.

Fig. 46. The sizes of valves (неодинаковы for various models of engines): and — diameter of a plate of the valve; b — diameter of a core of the valve; with — length of the valve; d — a corner of a facet of a saddle of the valve (45 )

Fig. 47. A valve plate: and = 3,5 mm; b = 0,5 mm

To take the measurements of valves according to fig. 46 and to replace all valves which are not corresponding to these sizes. It is necessary to consider distinctions between inlet and final valves. Width of a saddle of the valve and (fig. 47) and a thickness of an edge of the valve b should correspond to the specified values. On one of valves the size should not be less than 0,5 mm.

If the ends of cores of valves are worn out, a core surface it is possible прошлифовать on the machine tool, having removed a layer of metal no more than on 0,50 mm.

Fig. 48. Check of deformation of a head of the block of cylinders with the help щупа and a measuring ruler

It is necessary to clear carefully привалочные surfaces of a head of the block of cylinders and the block of cylinders and to check up a surface of a head of the block on deformation. To establish for this purpose on it a measuring ruler, as is shown in fig. 48, and to define by means of measuring щупа a backlash in longitudinal, cross-section and diagonal directions between the block of cylinders and a block head. If in a backlash passes lamellar calibre in the thickness more than 0,10 mm a head it is necessary прошлифовать. If a backlash in any place more considerable the head is subject to replacement.

Flat grinding of a head can be spent until its minimum height equal of 135,60 mm is maintained. The height is measured by a ruler, as is shown in fig. 39. If height of a head of the block of cylinders less than this value, it is necessary to replace a head.

The camshaft of each type of the engine has a corresponding designation. At camshaft replacement it is necessary to consider engine type.

Fig. 49. A camshaft designation

For camshaft identification between a cam of the inlet valve and a cam of the final valve of the first cylinder in a place specified by an arrow on fig. 49, the designation is beaten out. Besides, corresponding by image it is executed маркировочный a corbel which can have one of the forms specified in drawing 1–4.

In a place specified by an arrow, the symbol 030 AS or 030 AN is beaten out. The corbel looks like, corresponding 1 and 2 or 1 and 4.

In a place specified by an arrow, the symbol 032 N is beaten out or 032 R.Pojasok look like, corresponding 1 or 1 and 3.

In a place specified by an arrow, the symbol 030 ВА is beaten out. The corbel is not present.

In a place specified by an arrow, the symbol 030 АМ is beaten out. The corbel is not present.

Fig. 50. Definition of palpation of a camshaft

To establish a camshaft with both necks of trailer bearings in prisms, to clamp in the lathe centres, as is shown in fig. 50, and to establish стрелочный the indicator on a neck of the average bearing. Slowly to rotate a camshaft and to read out indicator indications. If the indication exceeds 0,01 mm the shaft is deformed also it it is necessary to replace.

To check up necks of bearings on presence of defects.

For backlash check at work of bearings of a camshaft it is necessary to use strips from polymeric material Plastigage. Check to spend without pushers. The control is spent as follows:

- Carefully to clear apertures of bearings in a head of the block of cylinders and covers of bearings and to insert into them a shaft. Some times to turn it;

Fig. 32. The Camshaft in installation position (bearings are numbered): And — a wide ledge; In — numbers of covers

- To put a small strip of polymeric material Plastigage in a cross-section direction on the top party of each neck of bearings and to establish covers of bearings according to their numbering and an arrangement (fig. 32 see);

- In regular intervals to tighten nuts of covers, beginning from the centre, till the moment equal 6 Нм (to use for this purpose динамометрический a wrench with small divisions of a scale), and after achievement of limiting value to tighten each nut for one 1/4 of turn (90 ). After that a shaft not to turn any more;

- Again serially to disconnect covers and by means of calibre being in complete set Plastigage to measure width of the flattened out strip. If it is established that the width exceeds 0,10 mm it means that limiting value of deterioration of the bearing, and a shaft (in most cases is reached and a head of the block of cylinders) it is necessary замененить. For measurement axial люфта a camshaft to establish it in a head of the block of cylinders (without pushers) and to fix by means of a cover of the central bearing. To put a head of the block of cylinders on a smooth surface. To establish at a camshaft end face стрелочный the indicator (fig. 51) and to move a shaft that to one, other party. Люфт should not exceed 0,15 mm. Otherwise the surface of a cover of the bearing is worn out.

Fig. 51. Check axial люфта a camshaft. To establish a shaft only together with a cover of the central bearing (marksman)