Nissan Maxima QX

since 1993 release

Repair and operation of the car



Nissan Maxima QX
+ Cars of the Nissan Maxima brand
+ Maintenance instruction
+ Settings and routine maintenance
- Engine
   + SOHC engines
   + DOHC engines
   - General capital repairs of the engine
      General information
      Check of pressure of oil
      Check of compression pressure in cylinders
      Diagnostics of a condition of the engine with use of the vacuum gage
      Alternative versions of schemes of recovery repair of the engine
      Removal of the power unit from the car - preparation and precautionary measures
      Removal and installation of the engine
      Order of dismantling of the engine by preparation it to capital repairs
      Dismantling of a head of cylinders
      Cleaning and check of a condition of a head of cylinders
      Service of valves
      Assembly of a head of cylinders
      Removal of conrod and piston assemblies
      Removal of a bent shaft
      Cleaning of the block of the engine
      Check of a condition of the block
      Honingovaniye of mirrors of cylinders
      Check of a condition of components of conrod and piston group
      Check of a condition of a bent shaft
      Check of a state and selection of inserts of radical and conrod bearings of a bent shaft
      Check of a condition of camshafts, pushers of valves and bearings
      Engine assembly order
      Installation of piston rings
      Installation of a bent shaft and check of working gaps of radical bearings
      Installation of a back epiploon of a bent shaft
      Installation of conrod and piston assemblies and check of size of working gaps in conrod bearings of a bent shaft
      Trial start and running in of the engine after capital repairs
+ Cooling systems, heating
+ Power supply system and release
+ Engine electric equipment
+ Control systems of the engine
+ Transmission
+ Coupling and power shafts
+ Brake system
+ Suspension bracket and steering
+ Body
+ Onboard electric equipment



Cleaning and check of a condition of a head of cylinders

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.

CLEANING

 PERFORMANCE ORDER

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.

Check of a state

Before making the decision on need of carrying out machining of a head of cylinders, carefully study its state. Having got acquainted with the material stated in the real subsection, make the list of the components needing special attention.

Head of cylinders

 PERFORMANCE ORDER

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.

Valves

 PERFORMANCE ORDER

1. Attentively check the working surfaces of valves for existence of signs of uneven wear, deformations, cracks, cavities and traces of a progar. Estimate extent of operation of cores of valves. Check whether there are no cracks in necks of cores. By rotation check valves for a bend. Make sure of lack of cavities and signs of excessive wear of end faces. Identification of any of the listed defects demands delivery of valves for recovery repair in a workshop of car service.


1 — End faces (shafts) of cores
2 — Flutes under installation of crackers of cutting locks of plates
3 — Cores
4 — Working facets
5 — the Final valve
6 — the Cylindrical part of a plate (corbel)
7 — the Inlet valve

2. Measure width of a cylindrical part (corbel) of a plate of each of valves. If width of a corbel appears less than the value stipulated in Specifications, replace the valve.

Components of valves

 PERFORMANCE ORDER

1. Estimate degree of wear of face parts of each of valvate springs, check springs for existence of cavities. Measure the free length of valvate springs, compare results of measurements to requirements of Specifications. If the spring is shorter than the lower admissible limit, it is sunk and is subject to replacement. Check also for compliance to standard requirements the efforts developed by springs (better to charge performance of this work to experts of a workshop of car service). In the absence of confidence in definition of a condition of springs it will be more correct to replace them.

2. Establishing each of springs vertically on a flat surface, check severity of their tortsovka. The springs with violation of a tortsovka as well as which sank (see above) are subject to replacement.

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.

Camshafts, pushers of valves and assembly of yokes with axes

 PERFORMANCE ORDER

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).