4.2.7. Cleaning and survey of a head of cylinders and valves

When cleaning the head of cylinders and components of valves which is followed by detailed survey you need to be defined what work has to be performed with valvate system in the course of capital repairs of the engine.

In case in use the car the strong overheat of the engine was allowed, it is necessary to assume that the head of cylinders can be bent - carefully check it regarding detection of signs of a curvature.



1. Scratch out traces of old laying and possible deposits from a head of cylinders.
2. Clean off a deposit from combustion chambers and a mirror of cylinders, then carefully wash out a head of cylinders in kerosene or in other suitable solvent.
3. Scratch out strong coal deposits which could be formed on valves, then by means of a korshchetka remove deposits from rods and plates of the valve.


Before deciding what is required: machining or intervention of specialists in capital repairs of the engine - make sure that did all procedures for survey. Make the list of all necessary procedures requiring attention.

Head of cylinders


1. Carefully examine a head regarding detection of cracks, signs of leaks or other damages. In case of detection of cracks the head of cylinders has to be replaced.

2. By means of a template (a metal line and an edge of the shchupovy measuring instrument) check whether the surface of a head of cylinders is bent. In case of detection of a curvature it can be eliminated by means of machining provided that height of a head of cylinders will remain in admissible Specifications limits.

3. Examine saddles of valves in each of combustion chambers. In case of detection of strong pointed corrosion, cracks or progar, saddles have to be replaced or pierced by specialists in capital repairs of the engine. In case of only insignificant pointed corrosion it can be removed by grinding of plates of valves and saddles by means of a thin abrasive for grinding in of valves as it is described below. Pay attention that final valves have a red-hot covering and though they can be ground in by means of paste, should not be exposed to machining.
4. Examine the directing plugs of valves regarding detection of wear by installation of the corresponding valve and verification of a side side play by rocking of the valve here and there. Let's allow only very insignificant side play. In case the side play is too big, take the valve. Measure diameter of a rod of the valve (see below), and replace the valve in case it is worn-out. In case the rod of the valve is not worn-out, wear has to be in the directing plug. In this case the directing plug has to be replaced. It is the best of all to make replacement of the directing plugs of valves in representative offices of SAAB or in the workshop specializing in capital repairs of engines - there is a necessary equipment and tools.



1. Examine a plate of each valve regarding detection of pointed corrosion, progar, cracks and the general wear. Examine rods of valves regarding detection of scratches and wear of edges. Rotate the valve on a flat surface for the purpose of detection of existence of curvatures. Check whether there is no corrosion and excessive wear on a tip of a rod of each valve. In case of detection of damages or wear, replace the valve.

2. If at this stage the condition of the valve seems satisfactory, measure diameter of a rod of the valve in several points by means of a micrometer. Existence of divergences between various measurements indicates wear of a rod of the valve. In this case the valve has to be replaced.

3. If valves appeared in good shape, they have to be lowered on the saddles for the purpose of check of their smoothness and gas-tightness. If saddles have signs only of easy pointed corrosion or were pierced, then only processing by means of thin pritirochny paste is necessary for them. Rough pritirochny paste should not be used for grinding in of valves unless the saddle too strongly burned through or has a deep sink. In case of detection of signs of such damages the head of cylinders and valves have to be provided for survey to experts who will solve whether there is enough pro-point of a saddle or replacement of the valve with installation of a new saddle of the valve is required (if it is possible).
4. Grinding in of valves is made as follows. Establish a head of cylinders head over heels on a workbench.
5. Grease a valve saddle surface with pritirochny paste of the required grade and press the sticking pritirochny tool to a plate of the valve. By means of returnable rotary motions grind in a valve head to a saddle, periodically raising the valve for redistribution of pritirochny paste. For simplification of this operation under a head of the valve the easy spring can be placed.
6. When using rough pritirochny paste it is necessary to make grinding in only before emergence of a plain opaque surface, both on a valve saddle, and on the valve, then paste has to be removed and process is repeated with thin paste. The procedure of rubbing is considered finished at formation of a smooth indissoluble ring of a light gray opaque color on the surface of the valve and on a valve saddle surface. You do not make grinding in longer, than it is necessary - it can result in premature wear.
7. After the end of grinding in of all valves carefully wash away traces of pritirochny paste by means of kerosene or other suitable solvent before starting assembly of a head of cylinders.

8. For check of correctness of work of hydraulic pushers of valves it is necessary to perform measurement of distance from end faces of rods of valves to the surface of bearings of a cam-shaft. The received size has to lie in certain limits. This procedure can be made by means of the special measuring tool, available representative offices of SAAB, however measurement can be alternative it is performed by means of a steel ruler or a direct template. By installation of each valve in its directing plug in turn and measurements of distance between an end face of a rod of the valve and the surface of the bearing of a cam-shaft, make sure that the received values lies in the limits set by Specifications.

9. If the measured size lies out of the limits set by Specifications adjustment of provision of the ends of rods of the valve or height of saddles of valves has to be made. In case of excess of the lower limit, length of a rod of the valve has to be reduced, in case of excess of the most admissible value the valve saddle has to be processed. Address for council in representative office of SAAB or the specialist in restoration of engines.

Components of valvate system


1. Examine valvate springs regarding detection of damages, change of color, and also measure their free length.

2. Establish each spring on a flat surface and check perpendicularity. In case any of springs it appeared below minimum admissible free length or has damage, curvature or loss of elasticity, springs have to be replaced in a set.
3. Regardless of their state get new maslootrazhatelny caps of rods of valves.