Service of the Infiniti QX4 since 1996 of release
1. Introduction
2. Maintenance instruction
3. Routine maintenance
4. Engine
5. Cooling system and heating
5.1. Specifications
5.2. Antifreeze - general information
5.3. Service of the cooling system
5.4. Removal, installation and check of serviceability of functioning of the thermostat
5.5. Removal, recovery repair and installation of a radiator of the cooling system
5.6. Replacement of the water pump
5.7. Removal and installation of the fan of the cooling system
5.8. Air ducts of distribution of the air given to salon
5.9. System of automatic air conditioning – a design and the principle of functioning
5.10. Structure of the refrigerator highway of the air conditioning system
5.11. The K/V compressor, - the general information and the principle of functioning
5.12. A receiver dehumidifier - the general information and service
5.13. Check of serviceability of functioning and service of systems of heating and air conditioning
5.14. Diagnostics of the air conditioning system
6. Feed and control systems
7. Systems of start and charge
8. Transmission line
9. Brake system
10. Suspension bracket and steering
11. Body
12. Electric equipment


5.4. Removal, installation and check of serviceability of functioning of the thermostat

Before finally being approved in opinion on a thermostat exit out of operation, check the level of cooling liquid in system, a state and effort of a tension of belts of the drive of auxiliary units (see the Head Routine maintenance), and also serviceability of functioning of the measuring instrument of temperature.

One of possible jamming of the thermostat in open situation is the reason of too slow warming up of the engine (according to indications of the measuring instrument) — replace the thermostat new.

In case of an overheat of the engine touch the top hose of a radiator. If the hose is not heated, perhaps, the thermostat is jammed in a closed position, blocking circulation of cooling liquid through a radiator. Replace the thermostat.

Do not operate the car with the removed thermostat at all! At the same time control system feedback can be broken that will lead to increase in toxicity of the fulfilled gases and excessive increase in fuel consumption.

If the top hose is heated, it means that cooling liquid regularly circulates through a radiator, i.e. the thermostat is open (see Diagnostics of malfunctions of knots and systems of the car, Diagnostics of malfunctions of the cooling system).

The most exact results are yielded by check of the thermostat on a workbench (see below).



  1. Disconnect a negative wire from the battery.
  2. Empty the cooling system (see the Head Routine maintenance) — if replacement of mix was made recently, keep it for further use.
  3. Walk on the top radiator hose to the engine and find a thermostat casing cover.
  4. Weaken a collar and remove a hose from the connecting branch pipe. If the hose "stuck", grasp it with nippers (as it is possible closer to a cut) and try to rotate on a branch pipe for the purpose of destruction of the holding layer of deposits. The old, subject to replacement hose can just be cut (try not to scratch a branch pipe).
  5. If the surface of a branch pipe contacting to a hose is struck with corrosion, or mechanically damaged, it makes sense to replace a thermostat casing cover.
  1. Turn out fixing bolts and uncover a thermostat casing. If the cover "stuck", tap it the hammer with soft brisk. Prepare for collecting the spilled liquid.
  1. Try to remember adjusting position of the thermostat (a valvate finger up), then take it from a casing.
  1. Remove all traces of sealant and material of old laying from surfaces of a casing and a cover.
  2. Replace rubber sealing laying of a cover of the thermostat.
  1. Install the thermostat in a casing (do not apply any sealant). Track that it was developed by a pumping finger up, and the party equipped with a spring to the engine.
  1. Establish into place a cover and fix it by bolts, having tightened the last with the required effort.
  2. Connect a hose to a cover branch pipe and strongly fix it by a collar. Return into place all components which were removed for the purpose of ensuring access.
  3. Fill in in system necessary amount of cooling liquid (see the Head Routine maintenance).
  4. Start the engine and check it for existence of leaks and serviceability of functioning of the thermostat (see above).

Check on a workbench


  1. Remove the thermostat from the engine (see the Head Dvigatel).
  1. Tie up a piece of a wire to assembly of the thermostat and lower it in the capacity filled with water. There lower the thermometer.

Track that the thermometer and the thermostat did not adjoin to walls and a bottom of capacity!

  1. Begin to warm up slowly water, monitoring change of indications of the thermometer — operation of the valve of the thermostat has to happen in strict accordance with requirements of Specifications.
  1. Estimate the size of full opening of the valve — the nominal rate makes b — and = 8 mm.

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5.3. Service of the cooling system
on the following page"
5.5. Removal, recovery repair and installation of a radiator of the cooling system