Ford prescribes the replacement of spark plugs every 60,000 kilometers in the maintenance plan. If the old spark plugs do not start your Mondeo unsatisfactorily or before this time, or if it jerks after starting, then the spark plugs «went on strike»: due to burnt electrodes, for example. Or as a result of invisible cracks in the ceramic insulator. Mentioned cold start cracks «willingly suck» condensed fuel. And since the igniting sparks mostly follow the path of least resistance, they may no longer reach the electrodes. If you have any doubts about old candles, try your luck with a new set. Spark plugs should only be replaced when the engine is cold and using special spark plug wrenches or sockets.
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TECHNICAL DICTIONARY |
What changes «candle face»
Spark plugs are, to a certain extent, the main witnesses to the combustion process. Visually, the spark plug electrodes can tell the technician if the engine is running optimally. Therefore, always pay attention to the dismantled candles and their appearance:
The color of the thermal cone of the insulator is light gray, gray-yellow to reddish: a well-prepared air-fuel mixture - the engine runs economically.
The color of the thermal cone of the insulator is whitish: the air-fuel mixture is too lean - check the CO content; possibly incorrect ignition timing, defective control unit.
Thermal insulator cone, electrodes, spark plug body coated with velvety, matt black soot: spark plugs do not reach their self-cleaning temperature (frequent short distance driving), incorrect heat rating, rich air-fuel mixture, high CO content.
The thermal cone of the insulator, the electrodes, the body of the candle is covered with oily soot or oil soot: piston rings, valve guides or valve shaft gaskets are damaged. Use engine oil or fuel with additives whenever possible. Replace the spark plugs, change the oil and fuel grade, then check the condition of the spark plugs again. |
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60,000 km
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PROCEDURE |
- First remove the engine cover and disconnect the spark plug connector from the spark plugs.
- Loosen the spark plugs about three turns and carefully blow out the spark plug holes with compressed air. Thus, the polluting particles will not have a chance - through the candles - to get into the cylinders.
Deep in «underground»: spark plug connector. |
- Remove the spark plugs with a spark plug wrench and place them - outside the engine compartment - in cylinder order.
With a special candle assistant, no problem: dismantling the spark plugs. |
- Before installation, lightly clean the threads of the new spark plugs with copper paste and screw the spark plugs firmly into the appropriate holes. Then further tighten the spark plugs with a spark plug tool to almost 90°more (quarter turn). 90°corresponds to approximately the prescribed tightening torque of 25 Nm.
- If you are using used candles, thoroughly clean their threads with a brass brush before installation, then lightly lubricate, insert the candles, screw them in firmly and then tighten them an additional 15°. This will be enough: in the previously used candles, the gasket is already pre-pressed before the final installation.
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SAFETY INSTRUCTIONS |
Work with the ignition system
The legislator classifies the electronic ignition system as a dangerous component. Therefore, when performing all work on the ignition, special precautions must be taken. Pacemakers, for example, may fail during such work. To be sure that you will not have any complications, it is better to have all work on electronic ignition systems carried out by Ford workshops. Even when carrying out maintenance work, special care must be taken. - Never touch live parts of the primary and secondary electrical circuits with the ignition on - danger to life.
- Always turn off the ignition system when performing all service work. This applies equally to replacing spark plugs, as well as disconnecting and connecting electrical wires or connecting control devices.
- With the ignition on, shaking the car is enough to cause a high voltage pulse. Under the engine hood, you are in danger, in addition, individual parts of the ignition system can also fail.
- When performing electric welding work on your Mondeo, disconnect both battery terminals first.
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PRACTICAL ADVICE |
Spark plugs are firmly seated
To release firmly seated candles, never use «brute force»: Otherwise, threads in light metal cylinder heads can be destroyed. If this problem occurs, as an exception, warm up the engine and try your luck again. Be careful - a hot engine can quickly burn your hands. Therefore, wait with installation until the engine has cooled down. Our recommendations also have a technical justification: if cold spark plugs were installed in a heated power unit, then they sit as if welded. However, it will be easier to dismantle the spark plugs at the next replacement if, before installation, a little lubricate the threads with high-temperature resistant copper grease. Ignition module and cable - pay attention to them - Are the cable outlets and multi-pin connector firmly connected to the ignition coil and control unit? The outgoing ignition cables are slightly lifted due to air ingress into the female contact bridges and therefore ignition failure is possible (interruptions).
- Loose ignition cables cause surface leakage currents and uncontrolled flashovers.
- Check the coil housings for cracks or burn marks caused by overlapping sparks.
- Do the terminals make good contact with the plugs of the spark plugs? They must not be oxidized.
- Check the high voltage ignition wire, the insulation must not be damaged or pierced. Replace the cable immediately with cleaning or extinguishing points. In a defective wire, an ignition spark may already have jumped off in front of the spark plug (path of least resistance!) - at the same time, you can hear crackling and rattling in the engine compartment.
- Remove salt or lime deposits from the ignition wire.
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