Nissan Maxima QX

1. Scratch out all traces of material of old laying and sealant from the interfaced surfaces 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.
2. Remove all traces of a scum from walls of water channels.
3. 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.
4. "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!

5. By means of solvent and a brass wire brush clear combustion chambers of a deposit.
6. 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.

7. On SOHC engines wash out solvent of assembly of yokes with axes. Carefully dry components with use of compressed air and put them in an organized order. Wash out solvent and dry pushers of valves.

Use of compressed air will significantly facilitate implementation of the procedure (do not forget to put on goggles).

8. Wash out in solvent and carefully dry valvate springs, their plates and crackers of cutting locks. Try not to mix components.
9. 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.

1. Attentively check a head of cylinders for existence of traces of leak of cooling liquid, cracks and other damages. The burst head is subject to replacement without fail. In case of lack of confidence in definition of a condition of a head, it is necessary to send it for check to a workshop of car service. If repair is not possible, replace a defective head.

2. By means of the measuring instrument of planeness and the probe of lezviyny type check the interfaced head surface for existence of signs of deformation. If not planeness exceeds value, admissible on standards (see Specifications), the head needs to be sent to a pro-point in a mechanical workshop. One and з working parameters of heads of cylinders is their minimum admissible height which should not be belittled in the course of machining.

3. Check a condition of saddles of valves in each of combustion chambers. In case of identification of cavities, cracks, traces of a progar, the head should be subjected to special recovery repair which performance lies outside qualification of the average amateur mechanic and it has to be entrusted to specialists of car service.

4. By means of a special nutromer measure the internal diameter of the directing valve plug. After extraction of the measuring instrument from the plug measurement is made by its micrometer. Measure also outer diameter of a core of the valve. For the purpose of determination of size of a gap of landing of the valve in the plug subtract result of the second from result of the first measurement. Compare the obtained data with requirements of Specifications. Worn-out plugs are subject to replacement. when using of a nutromer enter it to the middle of length of the plug, then move up-down. Unevenness of resistance to movement of the measuring instrument demonstrates existence of conicity of the plug. In the absence of confidence when determining a condition of components do not hesitate to ask for the help experts.

3. Check plates of springs and crackers of their cutting locks for existence of cracks and signs of wear. All details which are in a doubtful state should be replaced new in order to avoid development of defects in the future.

1. The description of procedures of check of a condition of the listed components is provided in the Section Check of a Condition of Camshafts, pushers of valves and bearings. Assessment of a condition of bearing necks of camshafts has to be made before the head is sent a workshop for carrying out service of valves. Existence on necks of scratches, zadir and other mechanical defects a head is subject to replacement regardless of a condition of components of the valvate mechanism. At service of the SOHC engine it is also necessary to check a condition of yokes of the drive of valves with axes.
2. Replace all revealed defective components.
3. At considerable degree of wear of components of valves that is quite probable for the engine needing capital repairs, collect valvate assemblies, establish them on the regular places in a head (see the Section Assembly of a Head of Cylinders) and you pass to performing procedures of service of valves (see the Section Service of Valves).