7.2. System of recirculation of the fulfilled gases (EGR) - models of 3.0 l
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Performing procedures of service of components of system requires the manual vacuum pump with the vacuum gage. |
Principle of action
Principle of functioning of the EGR system
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In the purpose of decrease in level of content of nitrogen oxides in system of release a part of the fulfilled gases goes back to the engine. The main components of system of recirculation are the EGR valve modulating the valve and the thermal vacuum valve (TVV) (the arrangement of the first two on the engine is shown on an accompanying illustration). |
The modulating valve operates depth of the depression given on the EGR valve for the purpose of maintenance of constant level of recirculation of the fulfilled gases.
At a low temperature of TVV cooling liquid it is closed and blocks access of depression to the EGR valve, supports the last also in the closed state.
When temperature of cooling liquid reaches normal working value, TVV opens, providing access of depression to the modulating valve.
The diaphragm of the modulating valve is drawn in by the fulfilled gases from system of release and provides or blocks air supply in a vacuum tube of the EGR valve, operating that opening / closing of the last.
At low loadings or small turns of the engine when pressure of the fulfilled gases is not enough, the spring of a diaphragm overcomes this pressure, opening air supply. Respectively, the EGR valve remains closed.
At high loadings / turnovers of the engine pressure of the fulfilled gases also rises, overcoming resistance of a spring of a diaphragm and blocking air supply. At the same time the EGR valve is influenced by the full depth of depression that raises the level of recirculation of the fulfilled gases.
Check of functioning of system
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- Check a condition of all vacuum hoses. Replace defective.
- Start the engine and warm up it up to the normal working temperature. At the working engine open-close a butterfly valve, watching behavior of a diaphragm of EGR. The EGR valve has to open and be closed along with the gate.
- If conditions of check are not satisfied, check system components separately.
EGR valve check
- Kill the engine and disconnect a tube of giving of depression from the EGR valve.
- Connect the manual vacuum pump with the vacuum gage to the EGR valve and create depression of 120 mm of mercury in depth.
- The valve has to open and remain smoothly open yet not will depression is dumped, otherwise it needs to be replaced.
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Check of the modulating valve
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- Enter a piece of a wire of suitable length the lower union of the modulating valve.
- Slightly wring out a diaphragm and by means of the manual vacuum pump create depression on the top union of the valve.
- If the valve does not hold depression, it can be considered faulty.
- Check of the thermal vacuum valve
- Start the engine from a cold state. Disconnect a vacuum hose from the top union of the modulating valve.
- Apply a finger to the open end of a hose and increase engine turns. Depression should not be felt.
- Warm up the engine up to the normal working temperature. Again apply a finger to the end of a hose and lift turns. Now depression has to be felt.
- In case of need replace TVV (TVV arrangement on the engine is shown on an accompanying illustration).
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Check of the thermal vacuum valve
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- Start the engine from a cold state. Disconnect a vacuum hose from the top union of the modulating valve.
- Apply a finger to the open end of a hose and increase engine turns. Depression should not be felt.
- Warm up the engine up to the normal working temperature. Again apply a finger to the end of a hose and lift turns. Now depression has to be felt.
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- In case of need replace TVV (TVV arrangement on the engine is shown on an accompanying illustration).
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