Motorists periodically face the need to replace the timing belt, as well as the procedure for replacing oil and fuel filters. And if the latter can be done by the car owners themselves, it is customary to replace the timing belt at service stations. Replacement and adjustment, meanwhile, are fairly straightforward.
The timing belt transfers the rotational motion from the crankshaft to the coolant pump and camshaft. Replacing the belt and tension rollers is not difficult even for the owner of a car who is uninformed about the intricacies of mechanics. It is much more important to be able to correctly adjust the timing so that the cylinder clock sequence coincides with the operating mode of the intake and exhaust valves, otherwise the engine will "triple" or will work with a noticeable loss of power.
Before starting the adjustment
The belt is installed when the tensioning mechanism of the idler roller is released. It may be necessary to make the adjustment several times by removing and reinstalling the belt with the following sequence:
- loosen the tensioning mechanism locking bolt. It passes through a longitudinal cutout in the base hinge;
- loosen the roller with your hands, provide it free movement and remove the belt;
- adjust the timing;
- put on the belt so that the grooves coincide with the grooves on the pulleys;
- tighten the roller using the lever (pry bar) and tighten the fixing bolt;
- check the tension of the roller: between the pulleys it should turn 90 °, but not more.
Method of matching installation marks
Almost every engine has special marks for adjusting the timing belt. On the pulleys, they are made in the form of holes with countersinking, and on the engine housing itself and the cylinder head they are in the form of a pin, staple or needle. The essence of this method is that before installing the belt, it is necessary to set the camshaft and crankshaft pulleys strictly according to these marks. It is worth noting that since the timing gear pulley has half the teeth, the mark indicates only the beginning of one of the cycles. That is why, for the first time, it may not be possible to correctly adjust the timing: you will need to turn the camshaft pulley one revolution. The exact location and type of marks can be found in the car's manual.
The method of finding the TDC
If the mark on the crankshaft is not found, the correct pulley position is set at the top dead center (TDC) of the first cylinder. To do this, unscrew the spark plug and, using a dipstick to check the oil level, find the uppermost position of the piston in the cylinder, and then check the pulley again for matching asymmetric parts. It will not be superfluous to apply your own mark using a file or a small drill.
Method of enumerating positions of the camshaft
If the exact position of the marks cannot be established on the dispenser too, it will take up to four samples to set it in the correct position. After the TDC is found and the corresponding mark is applied to the crankshaft pulley, the timing pulley should be cranked to a tangible stop - the beginning of one of the cycles. After that, the belt is put on and a test is made to start the engine. If unsuccessful, the belt must be removed and the camshaft pulley must be rotated 180 ° with each run. If the engine starts, but there is strong vibration and inconsistency in the operation of the cylinders, this indicates the opposite of the clock sequence and the pulley can be cranked one revolution at once.
