TD diesel engine
1. Warm up the engine and leave it to idle.
The function of the EGR system can be recognized by the position of the mechanical EGR valve through the slotted holes on the back of the valve diaphragm housing. If necessary, you can shine a flashlight into these holes (see illustration).
The piston of the mechanical valve, when the engine is idling, should move towards the connection of the vacuum pump hose. In this case, exhaust gases are removed.
2. Ask the assistant to gradually increase the engine speed. As soon as the engine speed exceeds 1200 rpm, the piston of the mechanical valve should begin to move in the opposite direction from the connection of the vacuum pump hose, blocking the exhaust gas outlet for two seconds. After two seconds, the piston must move again to ensure exhaust gas recirculation.
3. Increase engine speed. At engine speeds above 3200 rpm, the partial load switch located on the injection pump is activated. The piston of the mechanical EGR valve again moves in the opposite direction from the connection of the vacuum pump hose towards the intake manifold and remains in this position. There is no exhaust gas discharge. If EGR does not function as described above, check the power supply to the EGR solenoid valve.
4. Warm up the engine.
5. Disconnect the power cable plug for the EGR solenoid valve.
6. Connect a tester with an LED light to the plug contacts.
7. Have an assistant start the engine. When the engine is idling, there should be power on the plug and the LED light should be on.
8. Ask the assistant to increase the number of revolutions of the engine. The LED indicator of the control device should go out for two seconds. With a subsequent increase in speed, the LED bulb should not light up.
If the tester's LED bulb reacts differently to the voltage supplied to the plug, then this may be due to a defective coolant temperature sensor or partial load switch. This can also be caused by a defect in the electrical wires of these parts.
A vacuum pump is required to check the condition of the mechanical EGR valve. Reduced pressure can be created by the mouth, but some effort will be required here.
9. Disconnect the vacuum hose from the vacuum pump from the valve.
10. Connect the vacuum pump and apply vacuum to the mechanical valve. The piston of the mechanical pump should begin to move towards the connection of the vacuum pump hose.
11. Supply air to the vacuum pump. The mechanical valve should close and this should be audible. If no characteristic closing noise is heard, the valve is defective and must be replaced.
EGR solenoid valve - check
The EGR solenoid valve is located behind the air filter in the rear right side of the engine compartment (see illustration 4.0)
12. Warm up the engine and stop it.
13. Set the key in the ignition to position «warm up». In this position of the key in the ignition lock, power is supplied to the circuit vacuum pump - mechanical exhaust gas recirculation valve.
14. Disconnect the power plug for the EGR solenoid valve. In this case, the power supply to the circuit vacuum pump - mechanical exhaust gas recirculation valve is interrupted and the voltage flows in the free direction.
Coolant temperature sensor - check
The resistance of the sensor is measured, and for this you need an ohmmeter with a measurement range of 0-2000 Sigma.
15. Disconnect the sensor plug.
16. Measure the resistance between terminals A and C with an ohmmeter (see illustration and drawing).
The resistance value depends on the coolant temperature. At a coolant temperature of 20°C, it is 1000-1200 Sigma, and at 80°C it is 125-150 Sigma.
Partial load switch - check
The partial load switch is mounted on the injection pump above the pump control lever. The switch power plug is located at the bottom of the injection pump (see illustration 4.0a).
The resistance measurement of this switch is checked in the positions «Idling» And «Full load».
17. Disconnect the switch power plug.
18. Connect an ohmmeter to switch contacts. Contact resistance at switch position «Idling» is 0, and at full load, the ohmmeter should show infinite resistance).
The switch is adjusted on the stand and its settings cannot be adjusted. The adjustment of a new switch should be entrusted to a workshop.
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