Engine — Troubleshooting (Discovery 1)

Extraneous noises

A. The noise from a gas breakthrough in the exhaust system is identified with almost no difficulty.

B. Noise from the operation of attachments is identified after removing the attachment drive belt and also does not present any difficulties in identifying the cause of the noise.

B. Internal engine noise can be caused by a combination of faults and is the most difficult to identify. Examples of identifying only mechanical causes of noise are given here.

Symptom: slight valve knocking on a cold engine.

1. Check the engine oil level.

2. Check the oil pressure. If the pressure is normal, there is probably a problem with the valve drive mechanism.

3. To confirm the diagnosis, remove the valve covers. With the engine idling, alternately insert a 0.015 mm feeler gauge between the rocker arm and the valve. If the sound changes when the feeler gauge is installed, the drive in this valve is faulty (for example, a hydraulic pusher).

Symptom: loud metallic rhythmic knocking sounds when the engine is warm and at partial loads.

1. Check the engine oil level.

2. Check the oil pressure, if the pressure is normal, drain the oil, check for the absence of metal chips (dust) in the oil.

3. If traces of metal are found in the oil, the connecting rod bearing is probably damaged. To confirm the diagnosis, turn off the cylinders one by one (remove the high-voltage wire from the spark plug or disconnect the injector tube). If the knocking noise disappears or becomes quieter, the bearing is faulty.



4. If the previous checks did not reveal a malfunction, check the reliability of the flywheel and front crankshaft pulley fastening.

Symptom: Loud low-pitched knocking noises when accelerating.

1. Check the engine oil level.

2. Check the oil pressure, if the pressure is normal, drain the oil, check for the absence of metal chips (dust) in the oil.

3. If traces of metal are found in the oil, the main bearing is probably damaged or the flywheel and/or front crankshaft pulley is loose. To eliminate defects in the attachments and to facilitate identification of the cause of the noise, temporarily remove the attachment drive belt.

The engine won't start

1. Check the battery status

2. Check the start inhibit switch and automatic transmission drive adjustment.

3. If the shaft rotation is slow when starting (below 120 rpm) - check the starting system or try starting from a donor battery.

4. If there are no flashes when starting, check the ignition, fuel and exhaust gas toxicity reduction systems.

Problems after launch

Symptoms:

• a. The engine stalls after the load is released.
• b. Engine starts and stalls or idles rough.
• c. Misfires.

1. Check the operation of the injection system.

2. Check the vacuum hose routing.

3. Check that the high-voltage wires are connected correctly and securely.

4. Check the ignition, fuel and exhaust gas toxicity reduction systems.

(The article is based on data from the website www.lrman.ru)

Power reduction

1. Check the throttle cable adjustment and accelerator pedal travel (perhaps you replaced the rug on the floor with a thicker one).



2. Check the operation of the injection system and ignition adjustment.

3. Check the power supply systems (in particular the condition of the fuel filter) and reducing the toxicity of exhaust gases.

4. Check the oil pressure: if the pressure is too high, the valves will be slightly open due to incorrect operation of the hydraulic lifters.

5. If the oil pressure is high, check the pressure relief valve.

6. If previous checks do not reveal any problems, check the compression end pressure ("compression") and, on vehicles with automatic transmission, the gearbox and torque converter.

Pops in the muffler

1. Check the exhaust system for leaks.

2. Check the correct installation of the distributor and high-voltage wires.

3. Check the power supply system (composition of the mixture).

4. Perform a compression end pressure test.

Reverse flashes

1. Check that the distributor and high-voltage wires are installed correctly.

2. Check the power supply system (composition of the mixture) and the correct routing of vacuum hoses.

3. Perform a compression end pressure test.

The engine gets very hot

1. Check the coolant level.

2. Check the tension of the drive belt of the attachments (water pump).

3. Check the condition of the radiator grille, wash it if necessary.

4. Check for coolant leaks.

5. Check the operation of the fan viscous clutch, the condition of the fan blades and the installation of the fan diffuser.

6. Check the thermostat and radiator cap.

7. Check the coolant temperature sensor and gauge.

8. Perform a compression end pressure test (blown head gasket).



9. Check for water in oil and oil in water:

• if there is oil in the water, the block gasket, intake manifold gasket, or front cover gasket is broken (depending on the engine design),
• if both conditions occur, the radiator is broken (oil cooler),
• if there is water in the oil, the block gasket is broken or the seal of the lower belt of the cylinder liner is damaged.

The engine does not warm up

1. Check the operation of the fan viscous clutch.

2. Check the thermostat.

3. Check the operation of the air conditioner fans (always on).

4. Check the coolant temperature sensor and gauge.