Internal combustion engines are complicated machines, and they make a lot of noise. How do you know when the sound is something you should worry about?
Fortunately, there are a few distinct engine noises you should listen to. These may not be the result of serious damage or defect, but it’s always a good idea to get them checked out if they persist.
“Engine knock” can result from something as simple as low engine oil. Another less-serious cause of engine knock is a loose belt or pully beating against nearby components.
Engine bearing failure is the most common cause of engine knock and is a more severe issue. When bearings go out, excessive space is created between the engine components, and the parts can bump together.
There are other things that can cause engine knock, including loose torque converters or crankshafts. All of these are serious problems that require the attention of a professional.
A rattling engine could be due to low oil, causing valvetrain components to click together. Adding oil should fix this problem unless it is resulting from a defective oil pump.
Rattling could be due to a loose timing chain that has become stretched and is bumping against its cover. These are minor to replace, but don’t wait too long to do so. If the noise stops, it could mean that the timing chain has broken.
If your engine is rattling while the vehicle is idle, it could be an issue with the catalytic converter, which controls exhaust emissions by burning unused gases. Parts of a catalytic converter core can break off and begin rattling around inside. These are expensive to replace, but you will most likely need to do so in order to pass an emissions test.
“Spark knock” generates a rattling sound. This happens when the fuel is igniting before the spark plug fires. Although the condition exists while driving, it is most noticeable when your car is idling.
A clicking sound when you first start up your engine can result from several problems. One is “piston slap,” where the piston is bumping the sides of the cylinder that contains it. It can be a serious issue if left unchecked.
Another cause of ticking sounds after your engine has been running is rusted or corroded heat shields, which are there to prevent high exhaust temperatures from affecting other parts. Fortunately, they are inexpensive to replace.
Other Engine Sounds
Engines are complex machines, and noises can be the result of innumerable large or small problems. If your car is backfiring, this can be the result of a much more serious issue.
A persistent banging sound could be due to “rod knock, which is where the space between the rod bearings connecting to the crankshaft has worn wide. This situation will only get worse with time, so it should be addressed quickly.
If your engine sounds are the result of a minor accident and another motorist is at fault, their insurance will cover repair expenses. If the accident was your fault or the result of a weather event, including being struck by a tree falling, comprehensive insurance should pay for the repair.
What to Do About Engine Noises?
A common question is, “Is it safe the drive a car that is making a strange sound.” The answer to that question is “yes, but for a short distance.”
Simply because your engine is making a sound does not mean you should have it towed. But, get it to a repair shop as soon as possible, so they can assess what is causing the sound and prevent further damage to your engine.
We hope this information has helped you get a better sense of what may be causing unusual engine noises. Be sure to check out our other automotive and motorcycle maintenance and repair tips.