Whenever you hear a knocking noise or a ticking noise from your vehicle, it is a sign that something is wrong. It could be a result of a lack of lubrication, a sign that something has broken, or something is about to break. Now, some engines have a normal ticking sound, which is caused by the electrical components like relays and injectors. Also, the engine itself makes some noise, turning the way it does. However, in general, engines should only make a soft, ticking noise. There should not be a knocking noise. If your engine develops a knocking noise while driving, you might notice a warning light on the dashboard, telling you that there is a problem. If it’s a red light, you have to stop immediately. If it’s amber, you can manage the engine till you get to a mechanic.
Now, the first thing you should check when you notice a knocking noise from your engine is the oil level. The most common cause of low oil levels is an oil leak. This could be either external or internal. To find out if you have an external oil leak, check the floor underneath your vehicle in the morning. If you do not see any external oil leaks, then the leak could be internal. There are lots of sources of internal oil leaks. These include piston rings, valve guide seals, o-rings and so on. If your engine burns oil past the piston rings or valve guide seals, you will see blue smoke from the exhaust.
Also, other causes of ticking noises could be from various parts of the engine. For example, worn camshaft lobes can cause a ticking in the upper engine. In the lower engine, a worn crankshaft and connecting rod bearings could cause such a noise.
Once your engine develops such knocking noises or ticking noises, there is no quick fix. You have to replace the malfunctioning parts, or replace the entire engine itself. Once an engine is low on oil to make a knocking sound, it is usually too late. Thus, it is extremely important for you to always change your oil, even if you do no other maintenance on your vehicle.