How the timing belt can affect engine stoppage

the timing belt and our objective is to show how it can affect the sudden stoppage of the engine.
A timing belt, or cam belt (informal usage), is a part of an internal combustion engine that controls the timing of the engine’s valves. The timing belt/chain connects the crankshaft to the camshaft(s), which in turn controls the opening and closing of the engine’s valves.
A four-stroke engine requires that the valves open and close once every other revolution of the crankshaft. The timing belt/chain does this. It has teeth to turn the camshaft(s) synchronised with the crankshaft, and is specifically designed for a particular engine. In some engine designs, the timing belt may be used to drive other engine components such as the water pump and oil pump.
If, for instance, the timing belt breaks that synchronisation in the movement of the camshaft and crankshaft is distorted. This can result in pistons hitting on valves, causing to them to bend in the process. In extreme instances the pistons, which are cast out of aluminum, normally break resulting in the damage to cylinders causing oil to push up from the sump and mixing with the petrol. This stalls the engine in most cases.
Normally, the blame is placed on oil and other functions and no one really looks and attributes it to the timing belt. Most timing belts are usually replaced at 100 000 kilometres, however, it is better to do the replacement at about 95 000 kilometres.
In most cases there is a timing belt warranty light that comes on once the belt is due for a change. So it is critical to ensure that the timing belt counter is reset to zero after the change.
Basic tit-bits on changing the timing belt
Remove the timing belt cover and the timing cover. When removing the timing belt avoid meshing of the timing pulley and timing belt, secure one with a string. If the timing belt is disengaged and if the crankshaft pulley is at the wrong angle this can cause the piston head and valve head to be in contact with each other and can cause damage when removing the pulley at the correct angle. Remove idler pulley then the camshaft timing pulley, then cylinder head cover.
Inspection of the timing belt components
The timing belt should not be bent, twisted inside out; the belt should not come into contact with oil, water or steam.
Never utilise the timing belt tensioner when installing or removing the mount bolt of the camshaft timing pulley. Check idler pulley for oil leakages and if there is oil, replace the idler pulley then check whether it is turning properly.
Check timing belt tensioner but ignore if there are small traces of oil on the seal or the push rod but if you find leakage change tensioner, then install the timing belt.
Install the belt when the engine is cold. Do not use any cleaning detergents but merely wipe the pulley. When replacing the timing belt we recommend subject to your manufacturer’s handbook or manual that you use genuine parts and replace the complete tensioner unit instead of just a simple roller or idler as it can affect the longevity of the tension system.
Incorrect fitting and incorrect setting of
tensioner unit
When the belt is fitted ignoring the ambient temperature, which is 20 degrees Celsius before setting is done, there is a strong chance of it being loose when the engine runs at the operating temperature. If the belt is old and upon fitting it is placed on a mounting bore that was released and not torqued this could be a problem.
Overheating could be caused by malfunction of the thermostat, the water pump or water leakage through points of the water cooling system or the ignition timing. Overheating subjects lubricating oil to oxidation due to excess in temperature going beyond its safe working margins.
If the engine does not crank at all or maybe slow this could be an electrical fault. For an engine to perform its best it means a certain amount of fuel in its virgin form (uncontaminated) with a controlled air enough to burn with the fuel excesses of which will cause such power losses among other problems.
Mixture of oil and fuel – there should be a relationship between the oil that goes upwards to the top ring in the engine and the thicker tractions in the fuel which do not burn are pulled downwards to the sump and accumulate there. This is usually linked to heavy fuel consumption and black sooty deposits that forms around the exhaust pipe.
If it’s not well balanced the level of the oil in the sump will either rise or decrease.
Fitted to the pistons are rings that are for compression and the other ones for oil. If these rings are worn out oil may enter the combustion chamber, which will cause a mixture of fuel and oil.
With this mixture the quality of the fuel (octane number for the diesel) is greatly compromised which will lead to loss of power due to these weak compression. As a result the fuel consumption becomes high as you drive to maintain a certain speed at every gear change and subsequent travel speed. Blue smoke could be caused by worn out seals or worn engine bearings and as a thumb suck you will be topping up very often. Worn out valve stem seals on the head can have the same effect of mixing oil with fuel. Because of worn out engine components the oil can be heavily contaminated with combustion gases containing acids produced thereof which increase the rate of oxidation in oils.
In the process the oil will fail its purpose where coagulation of sludge will develop and in petrol powered engines the spark plug will have gum settlement inhibiting the plugs from giving a good spark required for combustion. In this scenario where oil is supposed to have a drainage mark of 20 000km will be drained at, say, 7 000km.
Black smoke is a result of unproportional mixture of air and fuel in petrol engines where air is starved may also cause semi-combustion. In diesel engines administration of excessive diesel fuel in the combustion chambers can also cause semi-combustion and in either case will signal a moderate to heavy black smoke that can be observed at the exhaust. Based on our experience with a Mazda BT50, we have observed that towards its due period for oil change we experience that type of black smoke and we have accepted it as an indicator.
White smoke is caused by a leakage within the cylinder head and that you might be topping up very often. Diesel engines especially in cold weather produce heavy smoke when starting up. However, in turbo-charged engines this could signal a possibility of a leaking oil seal in the turbocharger. Please attend.
At all times ensure you buy genuine oil so as to guard against wear and tear. At Obel, we value your comments. Hence, let’s meet again next week same corner.
l You can contact us through our numbers and or through G.Mbeya 0774 215 505 Or via email [email protected].
PROUDLY ZIMBABWEAN.