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



Check of compression pressure in cylinders

 PERFORMANCE ORDER

1. Results of check of compression pressure in cylinders allow to define the general condition of components of the top part of the engine (pistons, piston rings, valves, laying of a head of cylinders, etc.) and to qualitatively estimate degree of their wear. What is especially important, the analysis of information obtained as a result of check allows to narrow a range of the possible reasons of falling of a compression in cylinders, having rather precisely tied refusal to violations of functioning of quite concrete components, whether it be piston rings, valves, their saddles or laying of a head.

The engine has to be heated-up up to the normal working temperature, and the rechargeable battery is completely charged.

2. Begin with a clearing of candle niches (blow them compressed air as which source in this case the ordinary bicycle pump perfectly will approach). The main objective is prevention of hit of garbage in cylinders during performance of measurements.
3. Dump pressure in a power supply system (see the Head of the Power supply system and release). The fuel pump in the course of implementation of this procedure has to be switched-off.
4. Turn out from the engine all spark plugs (see the Head Nastroyki and routine maintenance). Record a butterfly valve in completely open situation.
5. On the models equipped with the ignition distributor disconnect from a cover of the last central (a bobbin wire) and ground it on the engine block. On models without distributor disconnect an electrical wiring from each of ignition coils.

6. Establish компрессометр in a candle opening of the first cylinder.

7. Turn the engine at least on seven steps and consider the indication of the measuring instrument. On the serviceable engine pressure has to increase quickly enough. The low pressure on the first step which is followed by its gradual increase on the subsequent speaks about wear of piston rings. If at a further provorachivaniye of a shaft pressure does not rise, it can be regarded as the evidence of leakages of valves or violation of tightness of laying of a head of cylinders (also the probability of existence of cracks in a head is not excluded). The congestion of deposits on working facets of plates of valves can also lead to decrease in compression pressure. Write down the maximum indication of a kompressometr.
8. Repeat the procedure for the remained engine cylinders. Compare results to standard requirements (see Specifications).
9. At excessively low results of measurement, fill in in each of cylinders through a candle opening of a little motive oil (two-three teaspoons) and repeat check.
10. If addition of oil leads to increase in pressure, it speaks about wear of piston rings. If the compression does not increase, leakages of valves or violation of tightness of laying of a head are the reason of its decrease. Leakages of valves can be connected with a burn-out of their saddles, either a deformation/burn-out or mechanical damages of working facets.
11. If pressure of compression is equally underestimated in two next cylinders, then with high degree of probability it is possible to speak about violation of integrity of laying of a head within its crossing point between these cylinders. Presence of cooling liquid at motive oil will confirm this assumption.
12. If pressure in one of cylinders is about 20% lower, than in other and it is followed by violation of stability of turns of idling, it is necessary to estimate degree of wear of cams of the drive of the corresponding valves on the camshaft.
13. Unusual overestimate of compression pressure usually is a consequence of an excessive nagaroobrazovaniye in combustion chambers. In this case the head of cylinders has to be removed for the purpose of carrying out decarbonization.
14. At excessively low results of measurements, and also in case of violation of uniformity of distribution of pressure between cylinders it will be useful to hold testing of the engine for leaks in the conditions of a workshop of car service. Such check will allow to define precisely a source of leak and to estimate degree of its gravity.