4.2.8. Recovery repair of a head of cylinders

General information

In engines of modern cars heads of cylinders of one of two types are used: with the top arrangement of valves (OHV) and with the top arrangement of the camshaft (OHC). The last type can be broken on the sensor switch of subgroup: with one camshaft of the top arrangement (SOHC, or just OHC) and with two camshafts of the top arrangement (DOHC).

Now heads of cylinders are made by a casting method of aluminum alloy that allows to lower considerably total the power unit at preservation of such vital properties as reliability and ability to heat removal.
To be fair it is necessary to notice that on an equal basis with aluminum at production of heads of cylinders rather wide circulation has also traditional cast iron. Regardless of material all heads are completed with saddles of valves. In some heads about two valves are the share of each of cylinders though recently the multivalvate configuration where each of cylinders can be equipped by three, four and even five valves gains ground. Thin mechanical grinding in of working facets of plates to saddles provides tightness of combustion chambers in a closed position of valves. Use of the directing plugs provides unambiguity of back and forth motion of valves and centering of the last relatively of saddles. In view of told critical value is gained by the size of a gap of landing of a core of the valve in the directing plug. At excessive gaps the consumption of motive oil usually raises, there can be losses of depression and the probability of damage of valvate saddles increases. Too dense landing of valves in the directing plugs is fraught with their zakusyvaniye that leads to inevitable decrease in the power developed by the power unit and increase in risk of jamming of the engine. Besides the directing plugs valves also surely are completed with the springs providing the necessary density of pressing of plates to saddles and their return to a closed position after the compelled opening under the influence of the effort developed by eccentric cams of the camshaft(s). For fixing of springs on cores of valves special plates and two-section cutting locks (crackers) are used. In the heads made of aluminum alloy for protection of the last against a wipe on valvate springs special adjusting washers are established.

Ideally, during capital (recovery) repairs of a head of cylinders replacement of all valves complete with springs and the directing plugs has to be made. However, depending on a condition of the served engine determined mainly by conscientiousness of the owner of the car, need for such replacement can disappear. Abnormality of adjustment of adjusting parameters of the engine is the main reason for premature wear of components of the valvate mechanism. So, long operation of the unit on the reenriched air-fuel mix often leads to washing away of oil from the directing plugs gasoline. Reimpoverishment of mix leads to excessive temperature increase of its combustion that leads to a burn-out of plates of valves and their saddles. Duration of service life of valvate springs it is directly connected with the inherent driver of the vehicle a driving manner, - frequent excess of turns of the engine inevitably leads to more bystry exit of springs out of operation.

Unfortunately, completely it is not possible to prevent wear of internal components of a head of cylinders. Nevertheless, by timely carrying out recovery repair with careful grinding in of valves will allow the owner of the vehicle to reduce material inputs due to extension of service life of a head of cylinders.

It is necessary to notice that at a burn-out only of separate valves it will be reasonable to make replacement of all their set. This statement belongs as well to other components of the valvate mechanism.

As it is not unpleasant, to define a condition of internal components of a head of cylinders perhaps only after its preliminary dismantling. The description of the procedure of dismantle of a head of cylinders on the models of cars of the Mitsubishi brand Considered in the present manual is given below in this Section.

Cleaning

 PERFORMANCE ORDER

1. Careful cleaning of a head of cylinders and components of the valvate mechanism with the subsequent detailed check of their state will help to determine the approximate volume of the forthcoming recovery work.

Strong overheats of the engine can lead to deformation of a head of cylinders and violation of planeness of its interfaced surfaces.

2. Scratch out all traces of material of old laying and sealant from the interfaced planes of a head of cylinders, the inlet pipeline and a final collector, - try not to damage surfaces. Application of a special razmyagchitel which should impregnate previously stuck deposits will significantly facilitate work, - ask in shops of automobile accessories.
3. Remove all traces of a scum from walls of water channels.
4. A rigid wire brush carefully clean all available cavities and openings. At strong pollution of canals the clearing of a head should be charged to experts.
5. "Banish" the tap suitable by the size each of bolted openings, having removed corrosion products, traces of old sealant from a carving and having restored the damaged rounds. In the presence of access to a source of compressed air, blow openings, having removed from them shaving and small garbage.

When using compressed air do not forget to put on goggles!

6. A wire brush smooth out a carving of hairpins of fastening of the inlet pipeline and a final collector.
7. Wash out a head solvent and carefully dry it. Use of compressed air will allow to reduce significantly the term of drying and will give a quality assurance of a clearing of badly available cavities and openings.

Different structures for removal of traces of a deposit significantly facilitating implementation of the procedure of cleaning can be got in many shops of automobile accessories. Remember that such means usually are chemically aggressive and have to be applied with observance of the appropriate measures of precaution, - strictly adhere to instructions of the manufacturers who are usually given on the label of a container.

8. Wash out solvent pushers of valves, then carefully dry them. Use of compressed air will significantly facilitate implementation of the procedure (do not forget to put on goggles).

The pushers equipped with hydroproofreaders should be put upside down in an oil bathtub. Remember that at assembly all components have to be installed strictly on the former places.

9. Wash out in solvent and carefully dry valvate springs, their plates, saddles and crackers of cutting locks, - try not to mix components.
10. Scratch out the bulk of the valves of deposits created on surfaces, then a wire nozzle to the electric drill finally smooth out surfaces of cores and plates of valves - you watch that valves were not mixed.


Dismantling

General information

The design of the head of cylinders (SOHC or DOHC) used on the concrete engine does not render basic value much of implementation of the procedure of dismantle of components of the mechanism of the drive of valves. Examples of appearance of heads of cylinders are presented on illustrations. It is only necessary to notice that when dismantling a head like DOHC special attention needs to be paid to care of marking of all removed components, - components of the drive of inlet valves should not be mixed at assembly with components final at coincidence of number of the cylinder and almost absolute external identity. As the mnemonic rule when marking details it is necessary to remember that the inlet camshaft with the accompanying components settles down from the inlet pipeline, final - from a final collector.



Heads with pushers of cup type

 PERFORMANCE ORDER

1. In the majority of heads of cylinders in the mechanism of the drive of valves pushers of cup type are used. Crackers of the cutting lock of a valvate spring are located at such design in a pusher nest. For dismantling of a head of this kind will be required the tool for tightening of valvate springs of strubtsinny type, a mandrel for removal of valvate springs and a small magnet for extraction of crackers of the cutting lock.

2. If did not do it yet, take the camshaft(s) and/or pushers of valves from a head of cylinders.

Put the removed components in accurately marked plastic bags. Marking has to guarantee a possibility of installation of components at assembly strictly on the former places.


3. Turn a head so that to provide a possibility of installation of a clamp on it for tightening of valvate springs, - usually the head keeps within horizontally pro-masonry surface to the performer and valvate springs from it.

4. Having enclosed a mandrel for extraction of a spring in a pusher nest, squeeze a spring.

5. Helping itself the screw-driver, by means of a small magnet take crackers of the cutting lock from the landing nest.
6. Release a clamp and remove a valvate spring.
7. Take the valve from a head of cylinders. At the corresponding complete set remove a maslootrazhatelny cap.

Special devices for removal of maslootrazhatelny caps are issued. It is alternatively possible to use usual nippers, - try not to damage pusher nest walls that is fraught with decrease in adequacy of landing of the last.

8. At the corresponding complete set remove an adjusting washer from a spring, - again use a magnet or the screw-driver.
9. Working in a similar manner, remove components of the remained valves. Remember that all components should be put in accurately marked containers or packages.


Heads with pushers of lever type

 PERFORMANCE ORDER

1. For compression of valvate springs on heads of this type the special tool of standard type is usually used. However, on some models for installation of such tool it can appear insufficiently empty seat, - in such cases it is necessary to use the tool of strubtsinny type described above.
2. If did not do it yet, remove components of the mechanism of the drive of valves (levers of the drive of valves or a yoke with the axes) and take the camshaft(s). At the corresponding complete set remove also hydraulic proofreaders of valvate gaps.

All removed components should be put in an organized order, special attention paying marking clearnesses, - at assembly they have to be established strictly on the former places!


3. Turn a head so that to provide an empty seat under installation of the tool for compression of valvate springs.

4. Having started the tool, squeeze a spring of the first valve, having completely unloaded its plate.

Owing to development of a nagaroobrazovaniye the plate can "stick" to crackers of the cutting lock and for release it should be tapped slightly the hammer.

5. By means of a small magnet take crackers of the cutting lock from landing to a flute on a valve core.

6. Release the tool and remove a plate and a spring from a valve core.

7. At the corresponding complete set remove a maslootrazhatelny cap.

It is easier to remove usually maslootrazhatelny cap from the valve taken from the engine (see below).

8. Turn a head so that to provide a possibility of removal of the valve from it.
9. Take the valve from a head of cylinders.

In case of need previously process edges of a flute for installation of crackers and an end face of a shaft of the valve a file with small tooth.


10. At the corresponding complete set remove an adjusting washer of a valvate spring, - use a magnet or the screw-driver.

11. Working in a similar manner, remove the remained valves from a head. Remember that all components should be put in accurately marked containers or packages.


Check of a condition of components

After careful washing and drying of the components of the valvate mechanism removed from a head it is possible to start check of their state. Carrying out some control measurements what a micrometer with a divorce of sponges 0 ÷ 25 mm will be necessary for, - for measurement of diameter of cores of valves, the dial measuring instrument of plunger type / a telescopic nutromer, - for measurement of internal diameter of the directing plugs, a caliper and the special tool for assessment of degree of sag and correctness of a tortsovka of valvate springs will be required. In the absence of near at hand the listed tools performance of check of a condition of components should be charged to specialists of car service.

Valves

 PERFORMANCE ORDER

1. Check working facets of plates of valves for existence of cracks, cavities and traces of excessive wear. Burn-out traces the easiest come to light at survey of a cylindrical part (corbel) of a plate. The corbel has to be present at a plate without fail and have identical width on all perimeter of the valve. The rounding off or an oplavleniye of edges of a corbel specifies on прогар the valve. It is also necessary to estimate degree of not planeness of a face surface of a plate, - in the presence of an excessive deflection in its central part the valve is subject to replacement (it is desirable complete with the others).
2. Further it is necessary to check a condition of a shaft of a core of the valve, - attentively examine its end face and edges of a flute under installation of crackers of the cutting lock, - make sure of lack of zadir and agnails (especially if at removal of the valve it was necessary to resort to data processing of sites a file). The end face of a core of the valve has to be absolutely flat while some rounding off always takes place at a considerable run of the unit. In case of need make restoration of planeness of an end face by a valve pro-point.

3. Having taken for a drive a valve core on a flat surface (as that the windowpane can serve), check it for existence of signs of a bend.

4. In conclusion measure diameter of a core of the valve in several places by means of a micrometer. Compare among themselves results of measurement, - the core has to have uniform thickness on all the length. If the minimum tolerance of diameter of a core of the valve is not specified in Specifications, it is necessary to accept value of 0.025 mm as a reference point.

5. The defective or worn-out over an admissible limit valves are subject to replacement (it is desirable complete with the others).


Valvate springs, their holders and crackers of the cutting lock

 PERFORMANCE ORDER

1. First of all check valvate springs for existence of cracks, chips and other mechanical damages. Further it is necessary to measure the free length of springs, - try not to mix springs of inlet valves with springs of final. Compare results of measurements to requirements of Specifications.

2. By means of a ruler and a carpenter's corner estimate adequacy of a tortsovka of each spring.

3. In the presence of near at hand special device, check the effort developed by springs. Compare results of measurements to requirements of Specifications.
4. The sunk, defective and excessively worn-out springs are subject to replacement (it is desirable for all a set).
5. Plates of springs seldom need replacement, nevertheless, estimate a condition of their working surfaces contacting to a spring and crackers of the cutting lock. In case of identification of signs of deformation or cracks make replacement.
6. Estimate degree of wear of internal and external working surfaces of crackers of cutting locks. In case of need crackers are replaced in a set with the valve.


Head of cylinders

At survey of a head of cylinders special attention should be paid to a condition of the directing plugs and saddles of valves. Also it is necessary to check casting of a head for existence of cracks and other mechanical damages and to estimate degree of not planeness of the interfaced surfaces.

The directing plugs of valves

 PERFORMANCE ORDER

1. Having made sure of serviceability of a condition of valves, it is necessary to estimate degree of wear of the directing plugs in size of gaps of landing of cores of valves at them.

Preferably nevertheless to replace valves.

2. Before starting measurements, attentively examine the directing plugs on existence of cracks, zadir, agnails and other mechanical damages. When using plugs of removable type (on all heads made of aluminum alloy) estimate density of their landing, - existence of any weak point is inadmissible. All plugs have to act on identical height (including from saddles of springs).

3. Fix the dial measuring instrument of plunger type from the spring party of a head of cylinders. Slightly grease a core of the valve and fill it on the regular place. Densely press a measuring instrument plunger to a side surface of a core of the valve around a shaft and nullify the device. Pull the valve here and there in the directing plug and consider the indication of the measuring instrument, - write down result. Deploy the measuring instrument under 90 ° rather initial situation and repeat check. Having compared results of measurements among themselves, estimate the size of ovality of the directing plug. Also compare results of both measurements to requirements of Specifications.

The special telescopic nutromer intended for determination of internal diameter of the directing plugs of valves are issued, - when using such device compare results of measurements to the standard requirements provided in Specifications.

4. The worn-out or damaged directing plugs are subject to replacement or a pro-point.


Saddles of valves

 PERFORMANCE ORDER

1. Make visual survey of saddles of valves. Pay attention to existence of cracks, cavities and traces of a progar. Approximately estimate depth of landing of saddles in a head, - excessive deepening speaks about wear of components. In case of identification of cracks of a saddle are subject to replacement.
2. In the presence of near at hand special tool, check saddles for existence of signs of ovality. Compare results of measurements to requirements of Specifications, in case of need make a pro-point.

In the absence of standard values it is necessary to consider maximum admissible ovality of 0.051 mm.


Assessment of planeness of a head

 PERFORMANCE ORDER

1. Carefully smooth out the interfaced surfaces of a head of cylinders, having completely removed from them all traces of material of old laying.
2. Check of planeness is made by means of the special measuring instrument and the probe of lezviyny type. Measurement is performed along DP of a head and on both diagonals of the interfaced surface.

As the measuring instrument of planeness the steel ruler put on an edge can be used.


3. If the size of not planeness exceeds 0.076 mm on length of 15.2 mm (or 0.152 mm at the full length of the interfaced surface), the head of cylinders is subject to a pro-point.

After a pro-point of heads of cylinders of V-shaped engines it is necessary to pierce as appropriate also landing flange of the inlet pipeline for the purpose of compensation of change of provision of the interfaced surfaces.


Check of a condition of casting of a head

 PERFORMANCE ORDER

1. Usually cracks in casting of a head appear around an arrangement of combustion chambers, however, the probability of their education and near candle openings, saddles of valves and the basic surfaces of levers of the drive of valves is not excluded.
2. Special attention should be paid to check of a state to flow near final ports.
3. It is necessary to remember that visual survey does not allow to reveal the latent defects of casting. Much more detailed picture of structure of a body of a head can be received during performance of defectoscopy with application of methods of a magnetic resonance (Magnaflux®), - for the heads made of cast iron, or with use of the fluorescing structures (Ziglo®), - for light-alloy heads. Checks of this sort can be always made for quite reasonable payment at car repair shops.
4. The head having mechanical damages is subject to replacement.


Camshafts and pushers of valves

The description of procedures of check of a condition of camshafts and components of the mechanism of the drive of valves see in the Section Removal and installation of camshafts and pushers of the drive of valves.

Methods of restoration of components

General information

The most part of recovery procedures has to be made in the conditions of a workshop of car service.

Grinding in of valves

 PERFORMANCE ORDER

Grinding in of valves is carried out in the last turn after a condition of all components of a head their necessary recovery repair / replacement is checked and is carried out.

1. If valves are recognized suitable for further use, it is necessary to make a pro-point of face surfaces of their shafts and grinding in of working facets to the saddles.

New valves are also subject to grinding in after which implementation they become rigidly tied to the saddles.

2. Turn a head of cylinders upside down.
3. Slightly grease cores of valves and fill them on the regular places in a head.
4. Raise the valve which is subject to grinding in over a saddle and apply on a working surface of the last of a little special pritirochny paste.
5. Slightly moisten a sucker of the pritirochny holder and fix the last on the flat party of a plate of the valve.
6. Rotating the driving handle of the tool between palms, begin to grind in the valve to the saddle. Try to intercept more often the handle, at the same time slightly changing position of the valve concerning a saddle in order to avoid formation of furrows.
7. Continue grinding in until on a working surface of a saddle the equal ring of opaque gray color of width, identical on all perimeter, is not formed.
8. Separate the drive and you pass to grinding in of the next valve.
9. In conclusion do not forget to wipe carefully components, having removed all traces of pritirochny paste and an abrasive from their surface.
Springs, plates and crackers of cutting locks
10. The components listed in subsection heading are not subject to recovery repair and in case of an exit of their system have to be replaced.


The directing plugs of valves

 PERFORMANCE ORDER

1. In automobile engines only two types of the directing plugs are applied: removable (are used in light-alloy heads) and built in (are used the heads made of cast iron).

Pig-iron heads sometimes are also completed with removable plugs.

2. Restoration of worn-out guides of plugs can be made by one of four ways: nakatka; installation of inserts; boring and replacement.
3. At a nakatka metal of a detail is deformed that leads to reduction of a gap. Centering of the plug is at the same time restored. Nakatka is the simplest and cheap method of restoration of the directing plugs, however demands existence of special tool base and leads to considerable reduction of service life of the restored detail.
4. The bronze insert can be installed in the worn-out directing plug after its preliminary boring. The inserts equipped with a carving are issued, - for their installation the plug needs to be cut previously a tap of the corresponding size. Thin-walled plugs of cutting type can be alternatively installed, - they refuel in the chiseled plug then razvaltsovyvatsya by the special tool and are pierced under the necessary size.
5. In the effective way, especially at restoration of plugs of the built-in type their boring under valves of the bigger size is. Boring is made by means of a special vertical drill in the range from 0.076 to 0.762 mm (most often - 0.381 mm). It is necessary to buy repair valves of the corresponding size.
6. For replacement of plugs of the built-in type they need to be drilled from a head. Then nests are chiseled under the required size and in them repair plugs are pressed. Landing of new plugs is carried out by means of the hammer and a step drift. Special attention at installation of repair plugs has to be paid to centering of their rather valvate saddles. Landing height of the new plug also has to be strictly to correspond original, - do not forget to measure it before removal of old plugs. Old plugs are tapped from a head also by means of the hammer and a drift. Before installation of repair plugs it is necessary to define whether they have to carry out sealing of a water shirt of a head or not, - if yes, it is necessary to use the corresponding sealant, otherwise the plug and walls of a reception nest before landing should be greased with assembly lubricant. Landing of plugs in a head is made from installation of valvate springs.

 Use of set of technological washers will help at control of depth of landing of plugs.


Saddles of valves

 PERFORMANCE ORDER

The pro-point of saddles of valves has to be made only after adjusting parameters of the directing plugs are brought into accord with requirements of Specifications.

After performance of replacement of the directing plugs of a saddle of valves are pierced without fail!

1. If saddles of valves are in satisfactory condition, then after implementation of grinding in of valves (see above) it is possible to start assembly of a head of cylinders (see below).
2. Restoration of the worn-out or damaged saddles has to be made in the conditions of a workshop of car service. At a pro-point of saddles special attention is paid to centering of their rather directing plugs of valves.


Pro-point of a head of cylinders

 PERFORMANCE ORDER

At restoration of strongly deformed head also bearing necks of the camshaft(s) have to be subjected to the aligning pro-point. Failure to follow this requirement is fraught with serious internal damages of the engine in attempt of its start!

1. At especially strong deformation of the interfaced surfaces the head is subject to replacement.
2. The pro-point of the interfaced head surfaces (if in it there is a need) has to be made in the conditions of a workshop of car service.

At removal the pro-point course from surfaces of a head of a layer of metal standard requirements to geometrical parameters have to be observed.

3. After return of a head from its work it is necessary to clean once again very carefully (see above).


Seal of cracks in casting to a head

In certain cases the burst head of cylinders can be restored. Along a crack in the head made of cast iron carving inserts are established. At restoration of light-alloy heads more effective welding application is though use of carving inserts is also admissible. Some defects can be eliminated only with application of the soldering or welding, - address for consultation specialists of car service.

Assembly

First of all it is necessary to prepare a workplace, having paid special attention to purity of surfaces and existence of sufficient free space. Take care of the equipment of the space for warehousing of the components which are subject to installation. All established details also have to be very carefully cleaned and dried up.

Heads with pushers of cup type

 PERFORMANCE ORDER

1. Installation of the components of valves drowned in a nest of a pusher on heads of this type requires the small screw-driver, a clamp for compression of valvate springs with a mandrel, a little white lubricant (tsiatim) and the mass of patience.
2. Slightly grease cores of valves and establish them on the regular places in a head of cylinders.
3. At the corresponding complete set establish where follows adjusting washers of valvate springs.
4. Establish new maslootrazhatelny caps (if those are provided by a design). If the cap is put on the directing plug, previously slightly grease an external surface of the last. If instead of a cap the sealing ring is used, it is established after compression of a valvate spring, but before landing to a core of the valve of crackers of the cutting lock.
5. Dress a spring and its plate on a valve core.
6. Establish a mandrel and squeeze a spring by means of a special clamp.
7. Working with the screw-driver as the pallet, fill bends of crackers of the cutting lock with dense lubricant, - it will help to record temporarily crackers on a valve core to a spring otpuskaniye.
8. Picking up the screw-driver (again use lubricant), put crackers on the regular places on a valve core, having densely pressed them to a surface of the last.
9. Slowly release the clamp squeezing a valvate spring, - track that crackers did not drop out, - and remove it from the engine.
10. Working in a similar manner, install components on the remained valves.

11. Establish pushers, the camshaft(s) (do not forget to check installation of valvate gaps) and the other components which were removed in the course of dismantle.


Heads with pushers of lever type

 PERFORMANCE ORDER

1. Slightly grease cores of valves and establish the last on the regular places in a head of cylinders.
2. At the corresponding complete set establish where follows adjusting washers of valvate springs.
3. Establish new maslootrazhatelny caps (if those are provided by a design). If the cap is put on the directing plug, previously slightly grease an external surface of the last. If instead of a cap the sealing ring is used, it is established after compression of a valvate spring, but before landing to a core of the valve of crackers of the cutting lock.
4. Dress a spring and its plate on a valve core.
5. By means of the special tool squeeze a valvate spring.
6. Put crackers of the cutting lock on a valve core.
7. Slowly release a valvate spring, - track that crackers did not drop out of a flute on a valve core.
8. Remove the tool squeezing a spring from a head.
9. Working in a similar manner, install components on the remained valves.
10. Establish pushers, the camshaft(s) (do not forget to make adjustment of valvate gaps, - see the Head Nastroyki and routine maintenance) and the other components which were removed in the course of dismantle.