Fig. 4.15. Location of the 6K-Poly-V poly V belt on the Zetec-SE engine pulleys depending on the vehicle equipment: 1 – crankshaft pulley; 2 – hydraulic belt tensioner pulley; 3 – Power steering pump pulley; 4 – guide roller; 5 – generator pulley; 6 – water pump pulley; 7 – air conditioner pulley
The auxiliary units (generator, water pump, etc.) of the Fiesta are driven by a poly V-belt; in the new OHC engines, this task is performed by a 6K-Poly-V belt. Ford mainly uses poly V-belts, which move especially flexibly along the radii of the belt pulleys. A hydraulic device regulates the belt tension.
If you have a car with air conditioning or power steering, the belt has different dimensions than the base model. Be sure to carry the appropriate poly V-belt in your trunk for replacement.
Pre-tensioning of the poly V-belt
V-belts only work well if they have the necessary pre-tension: they should be tight, but not too tight. A belt deflection of 3 to 5 mm is normal when pressing on the center of the belt branch between two pulleys. Tight belts will eventually destroy the bearings of the alternator, water pump (depending on the engine type) and air conditioning compressor. In addition, tight belts stretch and can subsequently break. On the contrary, sagging V-belts slip - this is noticeable by the creaking sounds. This has the most harmful effect on the alternator, since it does not produce enough charging current, which leads to a high load on the battery during short trips and when starting a cold engine. The poly V-belt is also damaged, its sides burn, and it wears out prematurely. In extreme cases, slipping poly V-belts can lead to engine overheating and severe damage to parts and assemblies (piston seizure, cylinder head gasket burnout). Although the Fiesta engine automatically adjusts the tension of the poly V-belt, check its condition occasionally.
SEQUENCE OF WORKS
1. Check the condition of the belt.
2. Turn the crankshaft several times by hand. This is the only way to reliably check the condition of the poly V-belt along its entire length. Poly V-belts often have one, but very deep, crack. And if this crack, unfortunately, is on the belt pulley during inspection, you will not notice it, which can ultimately lead to serious consequences, despite the inspection.
3. If you find the following damage on the poly V-belt, replace it immediately:
- uneven wear marks on the sides of the belt;
- porous, frayed belt edges or surfaces;
- cracks.
PRACTICAL ADVICE
Installing a poly V-belt
Never use a screwdriver to put a new belt on the pulleys. Otherwise, subsequent damage will be "programmed" on the underside of the belt in places where you inserted the screwdriver. After installing a used belt, the engine should run for about 3 minutes (if the belt is new - 10 minutes), then recheck the pre-tension. Before turning off the engine, slightly increase the crankshaft speed. After about 1000 km of run, recheck the belt tension (the deflection should be 3-5 mm).
Installing a poly V-belt
SEQUENCE OF WORKS
1. Loosen the mounting bolt on the generator tension bracket.
2. Loosen the bolt on the pivot support.
3. Turn the generator towards the engine.
4. Replace the old poly V-belt with a new belt.
5. Installation is carried out in the reverse order of removal.
PRACTICAL ADVICE
If the belt breaks
If the red battery charge indicator light comes on while driving, this indicates that the poly V-belt has broken. You will notice a hard blow to the wheel well or the front wall in the engine compartment. Do not continue driving under any circumstances, as the water pump is driven by the belt and the circulation of the coolant stops, and the remaining liquid in the cylinder block will quickly boil, you risk getting severe engine damage. Therefore, immediately replace the broken belt with a spare one or tow the car to the nearest auto repair shop.
TECHNICAL DICTIONARY
Fig. 4.16. Location of the hydraulic device for tensioning the toothed belt on Fiesta OHC/DOHC engines
Timing belt and camshaft
The Zetec-SE and 1.8D Endura-DE engines' timing mechanism is driven by a toothed belt from the crankshaft pulley. Toothed belts are not subject to maintenance, they are made of artificial material and reinforced with steel wire, and are tensioned by a hydraulic device. Ford recommends replacing the toothed belt after 150,000 km of vehicle mileage. Since the valve timing phases may be disturbed when replacing the belt, the replacement should be carried out at a Ford service center. Specialists will also check the functionality of the tensioner and, if necessary, replace it.