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2.3. Diagnostics of malfunctions of the cooling system

The engine overheats
The driving belt of the water pump is torn off or slips. Check (see an accompanying illustration), make adjustment of a belt or replace it.

Level of cooling liquid fell. Try to find out the reason of losses of liquid. It can be the modulation, external or internal leaks - address the corresponding subsection below.

Do not uncover a radiator on the hot engine at all. Wait for cooling of the engine, then wind a cover with a thick layer of rags and begin to turn off it slowly. Having reached the first emphasis, wait for dumping of excessive pressure and only then you can finally uncover.


The radiator cover is faulty. Check (see an accompanying illustration), replace.

Pass of air from a forward part of the heat exchanger of a radiator in back is broken. Blow a path from the back party of the heat exchanger compressed air, or pump over its water pumped under a pressure. The thermostat is faulty. Check, in case of need replace.

The thermostatic clutch coupling of the fan of the cooling system is faulty. Replace the coupling.

Circulation of cooling liquid is broken. Check, make necessary corrections.

Installation of a corner of an advancing of ignition is broken. Check, make adjustment.

Passability of system of production of the fulfilled gases is broken. Remove the cause of blocking or replace faulty section / component.

Configuration of composition of air-fuel mix is broken. Check how it is described in the Section devoted to diagnostics of malfunctions of a power supply system), in case of need make the corresponding corrections.

Level of motive oil fell. Immediately kill the engine and add oil to the required level.

Adjustment of brake mechanisms is broken or brakes "are taken". Check, make necessary adjustments or replacement of components (see the corresponding subsection of the Section devoted to diagnostics of malfunctions of the brake system).

Coupling revolves. Check, execute necessary repair.

Leaks through laying of a head of cylinders take place. Check, execute necessary repair.

The engine is not developed after capital repairs. Whether check excessively corresponding fixture is drawn. Kill the engine and let's it cool down.

The engine overheat usually is followed by emissions of steam from a motive compartment. A characteristic sign of violation of tightness of laying of a head of cylinders is the puzyreniye of cooling liquid at the working engine (see an accompanying illustration).

External leak of cooling liquid takes place

The hose collar weakened, or the hose is faulty (see an accompanying illustration). Tighten a collar or replace a defective hose.

Leaks from the radiator heat exchanger, or its tanks take place. Make necessary repair, or replace a radiator.

The bearing and/or epiploon of the water pump is worn-out or damaged. Replace the pump.

The drain stopper of a radiator weakened or is damaged. Tighten or replace a stopper.

External cracks in the block or a head of cylinders take place. Replace faulty components.

Leaks from a casing of the thermostat or the water pump take place. Replace a faulty component.

Leaks from the heat exchanger of a heater or via its crane take place. Make necessary repair, or replace a faulty component.

For identification of signs of external leak of cooling liquid park the car on the pure dry platform and warm up the engine up to the normal working temperature. Also check whether there are no moisture traces in interior of the car under the heater heat exchanger.

Internal leak of cooling liquid takes place

There are leaks through laying of a head of cylinders in a consequence of violation of planeness of the interfaced surfaces (any or both) a head or the block of cylinders. Check, pierce or replace a defective component (head/block). Replace laying.

Cracks in a head or the block of cylinders take place. Replace a faulty component.

For identification of signs of internal leak of cooling liquid take the probe of measurement of level of motive oil and examine its edge on existence of signs of foaming of oil. Start the engine and observe an exhaust. Excessive emission of steam demonstrates availability of cooling liquid combustion chambers. Check compression pressure (see the corresponding subsection in the Head Nastroyki and routine maintenance) for identification of the defective cylinder.

Violation of circulation of cooling liquid takes place

Adjustment of a tension is broken, or the driving belt (i) of the water pump is faulty. Adjust a tension, or replace a belt (i).

Level of cooling liquid fell in system. Add, make check of system on leaks.

There was a partial violation of passability of tubes of the heat exchanger of a radiator. Make obratnopotochny washing or replace a radiator.

Excessive adjournment of a scum in water channels of the engine takes place. Make obratnopotochny washing of the block of cylinders.

The thermostat is faulty. Check, in case of need make replacement.

There was a collapse of hoses of a radiator. Check, replace defective hoses.

The water pump is faulty. Replace.

It is the simplest to check violation of circulation by removal of a cover from a radiator and observation of turbulence of liquid after warming up of the engine up to the normal working temperature.
At serviceable system turbulence has to arise at partial opening of a butterfly valve. Under the most adverse conditions when there are at the same time several violations, diagnostics can be executed by an exception of serviceable components during consecutive performance of checks in the listed order.